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Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan Earthquake
Author’s Accepted Manuscript Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan Earthquake Naoki Nakaya, Harumi Nemoto, Carine Yi, Ayako Sato, Kotomi Shingu, Tomoka Shoji, Shosuke Sato, Naho Tsuchiya, Tomohiro Nakamura, Akira Narita, Mana Kogure, Yumi Sugawara, Zhiqian Yu, Nicole Gunawansa, Shinichi Kuriyama, Osamu Murao, Takeshi Sato, Fumihiko Imamura, Ichiro Tsuji, Atsushi Hozawa, Hiroaki Tomita
PII: DOI: Reference:
www.elsevier.com/locate/ijdr
S2212-4209(17)30371-0 https://doi.org/10.1016/j.ijdrr.2018.02.037 IJDRR819
To appear in: International Journal of Disaster Risk Reduction Received date: 17 December 2017 Revised date: 18 February 2018 Accepted date: 21 February 2018 Cite this article as: Naoki Nakaya, Harumi Nemoto, Carine Yi, Ayako Sato, Kotomi Shingu, Tomoka Shoji, Shosuke Sato, Naho Tsuchiya, Tomohiro Nakamura, Akira Narita, Mana Kogure, Yumi Sugawara, Zhiqian Yu, Nicole Gunawansa, Shinichi Kuriyama, Osamu Murao, Takeshi Sato, Fumihiko Imamura, Ichiro Tsuji, Atsushi Hozawa and Hiroaki Tomita, Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan E arthquake, International Journal of Disaster Risk Reduction, https://doi.org/10.1016/j.ijdrr.2018.02.037 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan Earthquake
Naoki Nakaya a, Harumi Nemoto b, c, Carine Yi b, Ayako Sato a, Kotomi Shingu a, Tomoka Shoji a, Shosuke Sato b, c, Naho Tsuchiya a, Tomohiro Nakamura a, Akira Narita a, Mana Kogure a, Yumi Sugawarad, Zhiqian Yu b, c, Nicole Gunawansa e, Shinichi Kuriyama a, b, c, d, Osamu Murao b, c, Takeshi Sato b, c, Fumihiko Imamura b, c, Ichiro Tsuji a, d, Atsushi Hozawa a, d, Hiroaki Tomita a, b c, d a
Tohoku Medical Megabank Organization, Tohoku University, 2-1 Seiryo-Machi, Aoba-ku, Sendai
980-8573, Japan. b
International Research Institute of Disaster Science, Tohoku University, Aramaki Aza-Aoba 468-1,
Aoba-ku, Sendai 980-0845, Japan. c.
Core Research Cluster of Disaster Science, Tohoku University
d
Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
e
Washington and Lee University, Early-Fielding, 3 Lee Ave., Lexington, VA 24450, US.
*Correspondence to: Hiroaki Tomita, MD, PhD, Department of Disaster Psychiatry, International Research Institute of Disaster Science, Tohoku University, 2-1 Seiryo-Machi, Aoba-ku, Sendai 980-8573, Japan. Telephone: +81-22-717-7897 / Fax: +81-22-717-6285. [email protected]
Abstract
The effectiveness of tsunami drills in guiding evacuation behavior remains uninvestigated. Accumulation of evidence regarding the effectiveness of tsunami drills would be beneficial for improving survival and health of communities to be inundated by a tsunami. A questionnaire to inquire participants' location at the onset of the Great East Japan Earthquake and experience of the tsunami was issued as part of a survey of total adult residents of Shichigahama town whose houses were significantly damaged by the disaster. Along with the location information, self-reported information on participation in tsunami disaster drills and attendance of a lecture about tsunamis before the disaster and whether the participants evacuated after the earthquake was subjected to multiple logistic regression analyses adjusted for potential confounding factors. Amongst the 2,314 participants who were present in the town at the onset of the disaster and completed the questionnaires, 1,560 (67%) evacuated after the earthquake. The rate of evacuation was significantly higher amongst the population who participated in tsunami disaster drills before the event than amongst those who did not participate (multivariate-adjusted odds ratio [MOR] = 1.99, 95% confidence interval [CI] = 1.53 - 2.61, p < 0.01). However, other experience of earthquake and tsunami disaster prevention before the event did not affect evacuation behavior (MOR = 0.86 to 1.16). A survey of the population who survived the catastrophe provides initial evidence to advocate the administration of tsunami drills in seaside communities to enhance the evacuation behavior immediately after the disaster onset.
Keywords: Tsunami drill; Evacuation; the Great East Japan Earthquake; Preparedness; Public health; Disaster medicine
1. Introduction
On March 11, 2011, the Great East Japan Earthquake (GEJE) and the subsequent tsunami devastated the north-eastern coast of Japan. As of June 10, 2016, 18,452 people were recorded as dead or missing as a result of the GEJE [1]. Most of these deaths were due to drowning (92.4%) [2]. Evacuation behavior, especially between the onset of the earthquake and the tsunami arrival, was a crucial factor deciding the fates of the seaside community members. Disaster drills have long been considered an effective disaster preparedness activity. For example, tsunami drills were advocated in the Tsunami Advisory issued by the Japanese Home Ministry soon after the 1933 Sanriku Tsunami. Currently, in Japan, the Fire Services Act obliges schools and workplaces to perform disaster drills, and local community-based voluntary organizations for disaster preparedness have also been founded throughout the country. However, the penetration of disaster/tsunami drills into the communities in Japan has been variable. According to a survey covering every school in Iwate, Miyagi and Fukushima prefectures, 93.8% of the schools had conducted disaster drills, and 62.0% of the schools located in the tsunami hazard map area had conducted tsunami drills before the GEJE [3]. Also, according to a survey of voluntary organizations for disaster preparedness in Miyagi prefecture (n = 1,904), 61.1% had conducted disaster evacuation drills before the GEJE. Among them, only 9.2% reported that the vast majority of the community members (over 80%) had participated in the drills, whereas 24.6%, 32.8%, 29.8%, and 3.6% reported participation rates of 50-80%, 30-50%, 10-30%, and unknown, respectively [4]. People caught in a tsunami may exhibit a variety of initial behaviors including moving towards the nearest tsunami evacuation site or a high place right away, where they can avoid the tsunami, staying around the potential inundated area for searching or helping their family members/others or securing properties. In case these behaviors would be planed or trained in advance, they may be useful to save lives of their own or surrounding personnel, especially ones who need special aids for
evacuation. Otherwise, some of the behaviors can risk their lives. More thorough tsunami drill implementation may facilitate sharing the consensus and confidence on their evacuation policy among community members as well as their evacuation skills, and reduce delay in an evacuation, risk of drowning and casualties in the next catastrophe. Tsunami drills have not been widely employed outside Japan either, with few exceptions, such as a number of schools in the United States that were mandated to perform drills [5]. The importance of tsunami drills has drawn wider attention since the 3rd World Congress of Disaster Prevention held in Sendai, Japan, and since the United Nations General Assembly designated the 5th of November as World Tsunami Awareness Day, with the first occurrence held in 2016 [6]. A challenge for the near future is to spread the practice of tsunami drills worldwide. The assessment of drills is crucial to improving evacuation [3-5], however, there have been few attempts to evaluate the efficacy of disaster drills [7-9]. One such example is a descriptive study based on a small sample size (191 residents) that collected statements suggesting that people who had participated in the disaster drills evacuated quickly after onset of the GEJE [7]. However, to our knowledge, no statistically verified evidence is available on whether participating in disaster drills in advance facilitates evacuation behavior. Because a catastrophe of this magnitude greatly affects the mental health [10-15], physical health [16-18], and social conditions [19] in the affected communities, epidemiological studies have been performed to address response strategies to post-disaster public health concerns [10-18]. Developing adequate evacuation behavior is crucial, not only to reduce fatal outcomes but also for the prevention of health consequences following a disaster. Thus, epidemiological evidence on the effectiveness of experience of earthquake and
tsunami disaster prevention should be accumulated for improving evacuation behaviors. This population-based study investigated whether experience of earthquake and tsunami disaster prevention facilitated the evacuation behavior after the GEJE onset in the affected coastal area.
2. Methods Shichigahama Town is located on a peninsula on the ocean side of Miyagi prefecture in Tohoku region of Japan, 20km northeast to the center of Sendai, the capital city of the prefecture. The land area is 13.19km2, and the central part of the town forms a hill, radially sloping down to the seven beach areas separated by headlands. The communities around the beach areas were devastated by the GEJE. This study was part of a project called the Shichigahama Health Promotion Project, which was conducted in cooperation with Tohoku University and Shichigahama Town [11-15]. The project includes surveys to evaluate the health conditions and psychosocial aspects of the communities in the town severely affected by the GEJE and health promotion activities for the communities. This survey aimed to evaluate the current overall health and life status of all residents of the town whose houses were completely or significantly damaged, or all community members, of the five severely devastated coastal areas of Shichigahama town, where the earthquake and the resulting tsunami completely or significantly destroyed 10% of the houses. The definition of the “completely destroyed” and “significantly destroyed” criteria were based on the building damage assessment conducted by the Shichigahama government, following the criteria issued by the Cabinet Office. The survey teams visited all households in the target area to ask for participation in the survey in September 2012. An informed consent form and questionnaire were handed directly to residents willing to participate and were subsequently collected. The study protocol was reviewed and approved by the Ethics
Committee of Tohoku University Graduate School of Medicine [11-15].
2.1. Study population From the study population of 7,036 adults aged 20 years or older, 6,840 (97%) were contacted by the survey teams, and 4,949 (70%) of those subjects completed and returned the questionnaire with the written informed consent. We identified 3,966 (56%) participants who completed questions about experience of earthquake and tsunami disaster prevention before the GEJE. Only the subjects who were present in Shichigahama town during the GEJE outbreak (n = 2,314) were subjected to the following analyses.
2.2. Experience relevant to tsunami and earthquake disaster preparedness before the GEJE Disaster preparedness efforts before the GEJE were assessed with a question; “Before the GEJE, had you ever attended a lecture about earthquakes or tsunamis to prevent disasters at school or in the local community? Please choose all applicable experiences from the following five items: (i) Attending a lecture about earthquakes at school and/or in the community before the GEJE, (ii) Attending a lecture about tsunamis at school and/or in the community before the GEJE, (iii) Participating in earthquake drills at school and/or in the community before the GEJE, (iv) Participating in tsunami disaster drills at school and/or in the community before the GEJE, or (v) Hearing about past earthquakes or tsunamis from a family member or an acquaintance before the GEJE.”
2.3. Evacuation behavior after the onset of the GEJE Evacuation behaviors immediately after the onset of the GEJE were assessed by choosing one of the three
items: (i) I evacuated without any preparation, (ii) I evacuated after preparation, or (iii) I did not evacuate. It was designed to differentiate the subjects firstly whether they evacuated (i and ii) or not (iii). Secondly, the people who evacuated were further separated into the subcategories (i) and (ii), considering that the tsunami drills conducted before the GEJE usually advised residents to engage in quick preparations for taking along emergency items including medicinal drugs.
2.4. Other information The addresses of the locations where subjects stayed at the time of the GEJE onset and where their home located were collected, along with age and gender, considering whether they stayed within or outside the area inundated by the tsunami and whether they stayed at home or went out should affect the evacuation behavior. The Geospatial Information Authority of Japan reported the inundation area caused by the tsunami following the GEJE using a geographic information system (GIS) [20]. The addresses provided by the subjects were assigned to the geographic data outlining the inundation area of the town using ArcGIS (ERSI, Redlands, CA, US), and the subjects were classified into subpopulations who stayed inside or outside the tsunami-inundated area at the time of the onset. When the subjects reported that they stayed at home at the time of the earthquake or when the address they provided as their location at the time of the earthquake was the same as their home address, the subjects were classified as “at home at the time of the GEJE onset”. When the address of their location at the time of the GEJE onset and their home address were different, the subjects were classified as “away from home at the time of the GEJE onset”. Since employment status and basic social network status can be major confounding factors in participating in tsunami or disaster drills in advance and evacuation behaviors after a disaster, relevant information was collected. Social network status
was measured based on the Lubben Social Network Scale (LSNS)-6 and classified into “socially isolated (score < 12)” or “non-socially isolated (score ≥ 12)” [21]. Moreover, since a person’s physical condition can be a major confounding factor in participating in tsunami or earthquake drills in advance and evacuation behaviors after a disaster, time spent walking (< 0.5 hour/day or ≥ 0.5 hour/day) and active medical treatment for physical disease (absent or present) were collected.
2.5. Statistical analyses Multiple logistic regression analyses were conducted to evaluate the associations between experience relevant to the earthquake and tsunami disaster preparedness and evacuation behavior after the onset of the GEJE, adjusting for gender, age, employment, social networking, daily activity, and medical conditions as potential confounding factors. Further, a factor regarding whether the subjects stayed within the tsunami-inundated area at the time of the earthquake, and a factor regarding whether they stayed at home or went out at the time of the earthquake were also taken into the above consideration. The data were analyzed using SAS 9.4 (SAS Institute, Cary, NC, USA), with the significance set at p < 0.05. 3. Results Amongst the 2,314 subjects who completed the questionnaire (with socio-demographic characteristics summarized in Table 1), 32% had participated in school- or community-based tsunami drills, 37% had attended a school- or community-based lecture about tsunamis, 44% had participated in school- or community-based earthquake drills, 52% had attended a school- or community-based lecture about earthquakes, and 60% had heard about lessons from past tsunamis or earthquakes from a family member or an acquaintance. Older, more socially connected subjects or subjects who lived in tsunami-inundated areas
tended to have experienced tsunami preparedness activities before the GEJE, although these trends did not show statistical significance. A total of 1,560 subjects (67%) were evacuated after the onset of the earthquake. Subjects who had participated in school- or community-based tsunami drills showed a significantly higher rate of engaging in evacuation behavior than those who had not participated (multivariate adjusted OR [MOR] = 1.58, 95% confidence interval (CI) = 1.31 - 1.91, p < 0.01). Experience relevant to earthquake and tsunami disaster preparedness, other than tsunami drills, did not show any significant difference with respect to evacuation behaviors (MOR = 0.86 to 1.16) (Table 2). Because proximity to the seaside should affect evacuation behavior, whether the subjects stayed within or outside the tsunami-inundated area was taken into consideration when evaluating the association between experience relevant to earthquake and tsunami disaster preparedness and evacuation behavior after the onset of the GEJE. When only the subjects who stayed outside the tsunami-inundated area were subjected to the analysis, those who had participated in tsunami drills showed drastically higher evacuation rates (MOR = 4.49, CI = 2.73 -7.54, p < 0.01). In the analyses of subjects who stayed inside the tsunami-inundated area, those who had participated in tsunami drills also showed higher rates of engaging in evacuation behavior after the earthquake (MOR = 1.20), although the results were not significant (p = 0.44). Regardless of whether the subjects stayed within or outside the inundated area, there was no significant association between actual evacuation and preparedness efforts other than tsunami drills, i.e. participation in earthquake drills, attending lectures on tsunamis or earthquakes, or hearing lessons about past evacuations (Table 3). Whether subjects stayed at home or went out should also be taken into consideration in determining the association between experience relevant to earthquake and tsunami disaster preparedness and evacuation
behavior after onset of the GEJE. Amongst the subjects who stayed home, those who had participated in tsunami drills showed significant positive associations with evacuation behavior amongst populations both within and outside the tsunami inundated area, with MOR values of 3.46 (CI = 1.52 - 8.44, p < 0.01) and 3.76 (CI = 1.40 - 11.06, p = 0.01), respectively. Amongst those who went out, those who had participated in disaster drills also showed a significant positive association with evacuation behavior, although only in subjects whose homes were located outside the tsunami inundation area (MOR = 2.55, CI = 1.08 - 6.30, p = 0.04) (Table 4). Whether people evacuated with or without any preparation was evaluated with multivariate logistic regression analyses adjusted for potential confounding factors. The percentage of respondents who evacuated after preparation was significantly higher (11%) amongst the population who had participated in a tsunami drill before the event (MOR = 0.55, CI = 0.38 - 0.79, p < 0.01). Amongst the respondents who evacuated those with no experience of tsunami drill, 65% evacuated without any preparation, and 35% evacuated after preparation. In contrast amongst those who had participated in a tsunami drill, 54% evacuated without any preparation, and 46% evacuated after preparation (Table 5).
4. Discussion To our knowledge, this was the first epidemiological study to investigate the association between tsunami or earthquake drill participation and evacuation behavior. The current study provides initial evidence to endorse participation in tsunami drills in advance of catastrophes as a means of significantly facilitating evacuation behavior. The effect was more obvious for people who were relatively far from the seaside area and who may not see the necessity for evacuation from the tsunami. This finding was important because by the time
the risk of the tsunami is distinctly realized, it could be too late; thus, people must be trained to evacuate even when they do not perceive direct signs of risk. Immediately after onset of the GEJE, hazard warnings were continuously provided to residents around the tsunami-inundated area, and people should have evacuated regardless of having participated in tsunami drills. It is important to determine what motivated people outside the tsunami-inundated area, who were also potentially endangered, to evacuate. Our data indicate the effectiveness of tsunami drills in facilitating evacuation. Our study provides evidence indicating that the effect of the disaster drill facilitating evacuation behavior was more prominent amongst people who stayed at home at the time of the disaster onset, regardless of whether their home was located within or outside the tsunami-inundated area. Evacuation in the event of being away from home may require further consideration in tsunami drills. Evacuation in the event of being away from home might require further consideration in tsunami drills. Firstly, the surrounding situation should be less familiar, and less evacuation guidance and support from the family and neighboring residents may be expected. Secondly, when people would be in a workplace, they may need to follow the decision of the employer or the workplace. However, experience to participate workplace drills was not specifically evaluated in the current study. Workplace drills should be recommended together with special training for persons with specific responsibility for directing staff and employees in evacuation behavior. The decision to evacuate should not be in the hands of the employer or manager unless they were specifically trained and had designated responsibility. Amongst the subjects who were away from home at the time of the onset of the earthquake, tsunami drills were significantly effective only for those who stayed outside the tsunami-inundated area (p = 0.04). It may have been relatively uncertain for people who stayed outside of the inundated area whether they should
evacuate and to where they should evacuate unless they had been trained, while it may have been relatively apparent regarding the necessity and direction of evacuation for people who stayed within the inundated area. Participating in a tsunami drill in advance of the GEJE facilitated some residents to engage in preparation before the evacuation amongst the population who evacuated after onset of the GEJE. Tsunami drills conducted in communities usually advise residents to make quick preparations to bring emergency supplies with them, including medicinal drugs. In addition to the importance of tsunami drills in enabling safe evacuation to save participants’ lives, training for quick preparation for taking along essential supplies is also important for survivors to maintain their health and aid in their reconstruction of their post-disaster life environment. However, participating in earthquake drills, attending lectures on tsunamis or earthquakes, or hearing about past tsunamis or earthquakes from family members or acquaintances did not show significant effects. Thus, the data indicated that particularly tsunami drills, but not any of the other considered activities, are crucial to facilitating the evacuation behavior of people endangered by the tsunami. Our findings endorsed the purpose of implementing disaster drills in schools, workplaces, and local communities located in seaside areas worldwide to encourage endangered people to engage in evacuation behavior. The benefits of tsunami drills may be due to the nature of the program, which usually enables participants to increase their awareness of the risk and strategies for response by walking through the field, rather than merely obtaining information. Participants are also trained in interacting and collaborating with the surrounding people. The factors that make tsunami drills more effective must be further elucidated. Several limitations of this study must be addressed. First, the nature, quality, and frequency of the tsunami
drills were not taken into account in the current study. Whether the contents and frequency of drills have any effect on behavior should further be investigated to gather the evidence to make specific recommendations in regards to the efficacy of preparedness. Second, the term “evacuation” was not defined in the questionnaire. For example, one might have had planned to evacuate together with a family member who needed aids for evacuation and took a while to search him/her before leaving for the evacuation center. In the case, it is not certain whether the one may or may not have had considered the searching behavior as a part of the evacuation. The obscureness in the definition of evacuation may have had limited this study to understand the nature of behaviors of people affected by disasters. Defining evacuation behavior is essentially difficult but important issue which remains to be investigated further. Third, to what extent and how people should prepare essential supplies before evacuation also require further investigation. Fourth, in this study, the term “mijitaku” in Japanese was utilized for “preparation” in the sentences “(i) I evacuated without any preparation, and (ii) I evacuated after preparation” of the questionnaire. The term “mijitaku” in a context of evacuation obviously indicates preparation regarding emergency items and dresses to survive and did not include being sure of their family members or going to help others. The issues regarding being sure of their family members or going to help others are the important factors to cause a delay of evacuation, which also need to be taken into account. Fifth, the subject of this study should have included people themselves who needed special aids for evacuation or people who lived with family members who needed special aids. These factors might hinder the evacuation behavior and might have influenced the results of this study. The above factors to determine the effectiveness of conducting tsunami drills remain to be examined. In conclusion, the survey on the population who survived the GEJE provided the initial evidence to advocate
for the administration of tsunami drills in seaside communities to enhance evacuation behavior immediately after the disaster onset, in a situation that tsunami drill participation rates among seaside communities have not been satisfactory. Our findings indicate that the planning and execution of disaster drills to promote effective evacuation behavior is important in schools, workplaces, and municipalities.
Acknowledgements We thank the government of Shichigahama town and residents of the town who have supported and participated to the survey. This work was supported by the Reconstruction Agency, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and the Japan Agency for Medical Research and Development (AMED) through the Tohoku Medical Megabank Project, Ministry of Health, Labour and Welfare, Japan, through a Health Sciences Research Grant for Health Services [H24-Kenki-Shitei-002, H25-Kenki-Shitei-002 (Fukko)], the Japanese Society for the Promotion of Science (JSPS) through a Grant-in-Aid for Scientific Research (C) (No. 26350863), a Grant-in-Aid from the Kurokawa Cancer Research Foundation, and an Intramural Research Grant for Special Project Research from IRIDeS, Tohoku University, Japan. The authors declare no conflicts of interest.
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Figure 1. Location of the town of Shichigahama in Miyagi prefecture, Japan
Table 1. Categories of groups regarding experience relevant to earthquake and tsunami disaster preparedness before the Great East Japan Earthquake (The table extends toward the right) Experience relevant to earthquake and tsunami disaster preparedness
Heard about past earthquakes and tsunamis from a family member or an acquaintance
Attended lectures regarding tsunamis at school and/or in the community
Category of group
Not experienced
Experienced
Not experienced
Experienced
Number of subjects Age in years (%) 20–49 50–59
935
1,379
1,449
865
242 (26) 93 (10)
358 (26) 219 (16)
453 (31) 188 (13)
147 (17) 124 (14)
60–69 70+ Women (%)
222 (24) 378 (40) 535(57)
325 (24) 477 (35) 855(62)
316 (22) 492 (34) 914 (63)
Employment status (%) Employed 341 (36) 568 (41) 586 (40) Unemployed 553 (59) 760 (55) 808 (56) Unknown 41 (4) 51 (4) 55 (4) Social network status based on the Lubben Social Network Scale-6 (%) Socially isolated 233 (25) 263 (19) 346 (24) (score < 12) Socially connected 617 (66) 1,032 (75) 982 (69) (score ≥ 12) Unknown 85 (9) 84 (6) 121 (7) Time spent walking (%) < 0.5 hour/day ≥ 0.5 hour/day
287(31) 578 (62)
470 (34) 865 (63)
Unknown 70 (7) 44 (3) Undergoing medical treatment for physical diseases (%)*1 Absent 535 (57) 764 (55) Present 400 (43) 615 (45) Location at the time of the GEJE onset (%) Inside inundation area 404 (43) 667 (48) caused by the tsunami Outside inundation area 254 (27) 343 (25) caused by the tsunami Unknown
277 (30)
369 (27)
231 (27) 363 (42) 476 (55) 323 (37) 505 (58) 37 (4) 150 (17) 667 (77) 48 (6)
476 (33) 899 (62)
32 (32) 63 (63)
74 (5)
5 (5)
848 (59) 601 (41)
451 (52) 414 (48)
634 (44)
437 (51)
374 (26)
223 (26)
441 (30)
205 (24)
Table 1 continued Experience relevant to earthquake and tsunami disaster preparedness
Participated in tsunami disaster drills at school and/or in the community
Attended a lecture about earthquakes at school and/or in the community
Category of group
Not experienced
Experienced
Not experienced
Experienced
Number of subjects
1,581
733
1,121
1,193
503 (32) 214 (14) 337 (21) 527 (33) 957 (61)
97 (13) 98 (13) 210 (29) 328 (45) 433 (59)
336 (30) 141 (13) 243 (22) 401 (36) 698 (62)
264 (22) 171 (14) 304 (25) 454 (38) 692 (58)
637 (40)
272 (37)
442 (39)
467 (39)
Age in years (%) 20–49 50–59 60–69 70+ Women (%) Employment status (%) Employed
Unemployed 874 (55) 439 (60) 628 (56) Unknown 70 (4) 22 (3) 51 (5) Social network status based on the Lubben Social Network Scale-6 (%)
685 (57) 41 (3)
Socially isolated 393 (25) 103 (14) (score < 12) Socially connected 1,075 (68) 574 (78) (score ≥ 12) Unknown 113 (7) 56 (8) Time spent walking (%) < 0.5 hour/day 524 (33) 233 (32) ≥ 0.5 hour/day 972 (61) 471 (64) Unknown 85 (5) 29 (4) Undergoing medical treatment for physical diseases (%)*1
279 (25)
217 (18)
737 (66)
912 (76)
105 (9)
64 (5)
382 (34) 672 (60) 67 (6)
375 (31) 771 (65) 47 (4)
Absent 955 (60) Present 626 (40) Location at the time of the GEJE onset (%)
344 (47) 389 (53)
644 (57) 477 (43)
655 (55) 538 (45)
Inside inundation area caused by the tsunami Outside inundation area caused by the tsunami Unknown
630 (40)
441 (60)
513 (46)
558 (47)
447 (28)
150 (20)
275 (25)
322 (27)
504 (32)
142 (19)
333 (30)
313 (26)
(The table extends further toward the right)
Table 1 continued Experience relevant to earthquake and tsunami
Participated in earthquake drills at school and/or in the community
disaster preparedness Category of group
Not experienced
Experienced
Number of subjects Age in years (%) 20–49 50–59 60–69 70+ Women (%) Employment status (%)
1,280
1,034
387 (30) 171 (13) 248 (19) 474 (37) 739 (58)
213 (21) 141 (14) 299 (29) 381 (37) 651 (63)
Employed 510 (57) 399 (39) Unemployed 711 (40) 602 (58) Unknown 59 (3) 33 (3) Social network status based on Lubben Social Network Scale-6 (%) Socially isolated 338 (26) 158 (15) (score < 12) Social connected 834 (65) 815 (79) (score ≥ 12) Unknown 108 (8) 61 (6) Time spent walking (%) < 0.5 hour/day 448 (35) 309 (30) ≥ 0.5 hour/day 747 (58) 696 (67) Unknown 85 (7) 29 (3) Undergoing medical treatment for physical diseases (%)*1 Absent 768 (60) 531 (51) Present 512 (40) 503 (49) Location at the time of the GEJE outbreak (%) Inside tsunami-inundated 537 (42) 534 (52) area Outside 334 (26) 263 (25) tsunami-inundated area Unknown
409 (32)
237 (23)
Study participants were classified whether they had experienced any of the five experience relevant to earthquake and tsunami disaster preparedness listed in the top row before the Great East Japan Earthquake (GEJE) (n = 2,314). Characteristics of each group regarding disaster preparedness before the GEJE are summarized regarding age, gender, employment status, social network status, time spent walking, physical health condition and location at the time of the GEJE onset. *1 “physical diseases” include stroke,
myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia. Table 2. The effect of each experience relevant to earthquake and tsunami disaster preparedness before the Great East Japan Earthquake (GEJE) on evacuation after the GEJE onset Category of group regarding each experience relevant to earthquake and tsunami disaster preparedness before the GEJE
Not experienced
Experienced
Heard about past earthquakes and tsunamis from a family member or an acquaintance Number of subjects who evacuated 608 / 935 952 / 1,379 / Number of total subjects 65 69 Percentage of subjects who evacuated 1.0 (Ref.) 1.06 (0.87 – 1.29) Multivariate adjusted OR (95% CI)
p-value
0.58
Attended a lecture about tsunamis at school and/or in the community Number of subjects who evacuated / Number of total subjects
956 / 1,449
604 / 865
Percentage of subjects who evacuated
66
70
Multivariate adjusted OR (95% CI)
1.0 (Ref.)
0.88 (0.68 – 1.13)
0.30
Participating in tsunami drills at school and/or in the community Number of subjects who evacuated / Number of total subjects
986 / 1,581
574 / 733
Percentage of subjects who evacuated
62
78
Multivariate adjusted OR (95% CI)
1.0 (Ref.)
1.99 (1.53 – 2.61)
<0.01
Attending a lecture about earthquakes at school and/or in the community Number of subjects who evacuated / Number of total subjects Percentage of subjects who evacuated
740 / 1,121
820 / 1,193
66
69
1.0 (Ref.) Multivariate adjusted OR (95% CI) Participated in earthquake drills at school and/or in the community Number of subjects who evacuated 831 / 1,280 / Number of total subjects 65 Percentage of subjects who evacuated 1.0 (Ref.) Multivariate adjusted OR (95% CI)
1.16 (0.93 – 1.45)
0.20
729 / 1,034 71 0.86 (0.68 – 1.08)
0.18
Multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had experienced each of the five experiences relevant to earthquake and tsunami disaster preparedness before the GEJE to the one among people who had not are shown in the table (n = 2,314). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown); and experiences relevant to earthquake and tsunami disaster
preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia. Table 3. The effect of each tsunami disaster preparedness effort before the Great East Japan Earthquake on the evacuation behavior of subjects who stayed inside or outside the tsunami-inundated area at the time of the onset Category of group regarding each experience relevant to earthquake and tsunami disaster preparedness before the GEJE
Not experienced
Experienced
Number of subjects who evacuated / Number of total subjects (%)
Number of subjects who evacuated / Number of total subjects (%)
ORs
ORs (95% CIs)
Heard about past earthquakes and tsunami from a family member or an acquaintance 340 / 404 1.0 569 / 667 1.01 Inside tsunamiinundated area (84) (Ref.) (85) (0.70 – 1.43) Outside tsunamiinundated area
94 / 254 (37)
1.0 (Ref.)
163 / 343 (48)
1.36 (0.94 – 1.95)
p-value
0.98 0.10
Attended a lecture about tsunamis at school and/or in the community 377 / 437 86 102 / 223 (46)
1.01 (0.64 – 1.60) 0.64 (0.40 – 1.01)
Participated in tsunami drills at school and/or in the community 525 / 630 1.0 384 / 441 Inside tsunamiinundated area (83) (Ref.) (87) 162 / 447 1.0 95 / 150 Outside tsunamiinundated area (36) (Ref.) (63)
1.20 (0.77 – 1.88) 4.49 (2.73 – 7.54)
Inside tsunamiinundated area Outside tsunamiinundated area
532 / 634 (84) 155 / 374 (41)
1.0 (Ref.) 1.0 (Ref.)
0.97 0.06
0.44 <0.01
After stratification of the subjects into two groups; subjects who stayed inside or outside the tsunami-inundated area at the time of the Great East Japan Earthquake (GEJE) onset, multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had experienced each of the three experiences relevant to earthquake and tsunami disaster preparedness before the GEJE to the one among people who had not are shown in the table (n = 1,668). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown); and experience relevant to earthquake and tsunami disaster preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia.
Table 4. The effect of experience of tsunami drill before the Great East Japan Earthquake on the evacuation behavior of subjects who stayed at home or not at the time of the onset No tsunami drill participation before the GEJE
Category of group regarding experience Number of subjects of tsunami drill before who evacuated / Number of total the GEJE subjects (%)
ORs
At home at the time of the GEJE onset (n = 763) 317 / 361 Inside tsunami1.0 (Ref.) inundated area (88) Outside tsunamiinundated area
60 / 109 (55)
1.0 (Ref.)
Trained with tsunami drill before the GEJE Number of subjects who evacuated / Number of total subjects (%)
ORs (95% CIs)
237 / 247 (96)
3.46 (1.52 – 8.44)
<0.01
36 / 46 (78)
3.76 (1.40 – 11.06)
0.01
48 / 56 (85) 48 / 74 (65)
0.70 (0.11 – 4.03) 2.55 (1.08 – 6.30)
p-value
Not at home at the time of the GEJE onset (n = 298) Inside tsunamiinundated area Outside tsunamiinundated area
63 / 74 (85) 49 / 94 (52)
1.0 (Ref.) 1.0 (Ref.)
0.69 0.04
After stratification of the subjects into the groups; subjects who stayed at home or not at the time of the onset of the Great East Japan Earthquake (GEJE), and for each of the subgroups, subjects who stayed inside or outside tsunami-inundated area at the time, multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had participated tsunami drills before the GEJE to the one among people who had not are shown in the table (n = 1,061). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown) ; and experience relevant to earthquake and tsunami disaster preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia.
Table 5. Experience of tsunami drills before the Great East Japan Earthquake and whether people evacuated with or without preparation Number of subjects who
Number of subjects who
evacuated without preparation
evacuated after preparation
Total
Number of subjects with no experience of tsunami drills before the GEJE
342 (65%)
183 (35%)
525 (100%)
Number of subjects who had participated in tsunami drills before the GEJE
208 (54%)
176 (46%)
384 (100%)
Amongst the 525 subjects who had no experience participating in a tsunami drill before the GEJE and evacuated after the event, 342 (65.1%) evacuated without any preparation and 183 (34.9%) evacuated after preparation. Amongst the 384 subjects who had participated in a tsunami drill before the GEJE and evacuated after the event, 208 (54.2%) evacuated without any preparation and 176 (45.8%) evacuated after preparation.
Highlights The evacuation rate was significantly higher among participants of tsunami drills.
Other experience of earthquake and tsunami disaster prevention did not affect evacuation behaviors.
The study provides initial evidence to advocate administration of tsunami drills.
PII: DOI: Reference:
www.elsevier.com/locate/ijdr
S2212-4209(17)30371-0 https://doi.org/10.1016/j.ijdrr.2018.02.037 IJDRR819
To appear in: International Journal of Disaster Risk Reduction Received date: 17 December 2017 Revised date: 18 February 2018 Accepted date: 21 February 2018 Cite this article as: Naoki Nakaya, Harumi Nemoto, Carine Yi, Ayako Sato, Kotomi Shingu, Tomoka Shoji, Shosuke Sato, Naho Tsuchiya, Tomohiro Nakamura, Akira Narita, Mana Kogure, Yumi Sugawara, Zhiqian Yu, Nicole Gunawansa, Shinichi Kuriyama, Osamu Murao, Takeshi Sato, Fumihiko Imamura, Ichiro Tsuji, Atsushi Hozawa and Hiroaki Tomita, Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan E arthquake, International Journal of Disaster Risk Reduction, https://doi.org/10.1016/j.ijdrr.2018.02.037 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Effect of tsunami drill experience on evacuation behavior after the onset of the Great East Japan Earthquake
Naoki Nakaya a, Harumi Nemoto b, c, Carine Yi b, Ayako Sato a, Kotomi Shingu a, Tomoka Shoji a, Shosuke Sato b, c, Naho Tsuchiya a, Tomohiro Nakamura a, Akira Narita a, Mana Kogure a, Yumi Sugawarad, Zhiqian Yu b, c, Nicole Gunawansa e, Shinichi Kuriyama a, b, c, d, Osamu Murao b, c, Takeshi Sato b, c, Fumihiko Imamura b, c, Ichiro Tsuji a, d, Atsushi Hozawa a, d, Hiroaki Tomita a, b c, d a
Tohoku Medical Megabank Organization, Tohoku University, 2-1 Seiryo-Machi, Aoba-ku, Sendai
980-8573, Japan. b
International Research Institute of Disaster Science, Tohoku University, Aramaki Aza-Aoba 468-1,
Aoba-ku, Sendai 980-0845, Japan. c.
Core Research Cluster of Disaster Science, Tohoku University
d
Graduate School of Medicine, Tohoku University, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
e
Washington and Lee University, Early-Fielding, 3 Lee Ave., Lexington, VA 24450, US.
*Correspondence to: Hiroaki Tomita, MD, PhD, Department of Disaster Psychiatry, International Research Institute of Disaster Science, Tohoku University, 2-1 Seiryo-Machi, Aoba-ku, Sendai 980-8573, Japan. Telephone: +81-22-717-7897 / Fax: +81-22-717-6285. [email protected]
Abstract
The effectiveness of tsunami drills in guiding evacuation behavior remains uninvestigated. Accumulation of evidence regarding the effectiveness of tsunami drills would be beneficial for improving survival and health of communities to be inundated by a tsunami. A questionnaire to inquire participants' location at the onset of the Great East Japan Earthquake and experience of the tsunami was issued as part of a survey of total adult residents of Shichigahama town whose houses were significantly damaged by the disaster. Along with the location information, self-reported information on participation in tsunami disaster drills and attendance of a lecture about tsunamis before the disaster and whether the participants evacuated after the earthquake was subjected to multiple logistic regression analyses adjusted for potential confounding factors. Amongst the 2,314 participants who were present in the town at the onset of the disaster and completed the questionnaires, 1,560 (67%) evacuated after the earthquake. The rate of evacuation was significantly higher amongst the population who participated in tsunami disaster drills before the event than amongst those who did not participate (multivariate-adjusted odds ratio [MOR] = 1.99, 95% confidence interval [CI] = 1.53 - 2.61, p < 0.01). However, other experience of earthquake and tsunami disaster prevention before the event did not affect evacuation behavior (MOR = 0.86 to 1.16). A survey of the population who survived the catastrophe provides initial evidence to advocate the administration of tsunami drills in seaside communities to enhance the evacuation behavior immediately after the disaster onset.
Keywords: Tsunami drill; Evacuation; the Great East Japan Earthquake; Preparedness; Public health; Disaster medicine
1. Introduction
On March 11, 2011, the Great East Japan Earthquake (GEJE) and the subsequent tsunami devastated the north-eastern coast of Japan. As of June 10, 2016, 18,452 people were recorded as dead or missing as a result of the GEJE [1]. Most of these deaths were due to drowning (92.4%) [2]. Evacuation behavior, especially between the onset of the earthquake and the tsunami arrival, was a crucial factor deciding the fates of the seaside community members. Disaster drills have long been considered an effective disaster preparedness activity. For example, tsunami drills were advocated in the Tsunami Advisory issued by the Japanese Home Ministry soon after the 1933 Sanriku Tsunami. Currently, in Japan, the Fire Services Act obliges schools and workplaces to perform disaster drills, and local community-based voluntary organizations for disaster preparedness have also been founded throughout the country. However, the penetration of disaster/tsunami drills into the communities in Japan has been variable. According to a survey covering every school in Iwate, Miyagi and Fukushima prefectures, 93.8% of the schools had conducted disaster drills, and 62.0% of the schools located in the tsunami hazard map area had conducted tsunami drills before the GEJE [3]. Also, according to a survey of voluntary organizations for disaster preparedness in Miyagi prefecture (n = 1,904), 61.1% had conducted disaster evacuation drills before the GEJE. Among them, only 9.2% reported that the vast majority of the community members (over 80%) had participated in the drills, whereas 24.6%, 32.8%, 29.8%, and 3.6% reported participation rates of 50-80%, 30-50%, 10-30%, and unknown, respectively [4]. People caught in a tsunami may exhibit a variety of initial behaviors including moving towards the nearest tsunami evacuation site or a high place right away, where they can avoid the tsunami, staying around the potential inundated area for searching or helping their family members/others or securing properties. In case these behaviors would be planed or trained in advance, they may be useful to save lives of their own or surrounding personnel, especially ones who need special aids for
evacuation. Otherwise, some of the behaviors can risk their lives. More thorough tsunami drill implementation may facilitate sharing the consensus and confidence on their evacuation policy among community members as well as their evacuation skills, and reduce delay in an evacuation, risk of drowning and casualties in the next catastrophe. Tsunami drills have not been widely employed outside Japan either, with few exceptions, such as a number of schools in the United States that were mandated to perform drills [5]. The importance of tsunami drills has drawn wider attention since the 3rd World Congress of Disaster Prevention held in Sendai, Japan, and since the United Nations General Assembly designated the 5th of November as World Tsunami Awareness Day, with the first occurrence held in 2016 [6]. A challenge for the near future is to spread the practice of tsunami drills worldwide. The assessment of drills is crucial to improving evacuation [3-5], however, there have been few attempts to evaluate the efficacy of disaster drills [7-9]. One such example is a descriptive study based on a small sample size (191 residents) that collected statements suggesting that people who had participated in the disaster drills evacuated quickly after onset of the GEJE [7]. However, to our knowledge, no statistically verified evidence is available on whether participating in disaster drills in advance facilitates evacuation behavior. Because a catastrophe of this magnitude greatly affects the mental health [10-15], physical health [16-18], and social conditions [19] in the affected communities, epidemiological studies have been performed to address response strategies to post-disaster public health concerns [10-18]. Developing adequate evacuation behavior is crucial, not only to reduce fatal outcomes but also for the prevention of health consequences following a disaster. Thus, epidemiological evidence on the effectiveness of experience of earthquake and
tsunami disaster prevention should be accumulated for improving evacuation behaviors. This population-based study investigated whether experience of earthquake and tsunami disaster prevention facilitated the evacuation behavior after the GEJE onset in the affected coastal area.
2. Methods Shichigahama Town is located on a peninsula on the ocean side of Miyagi prefecture in Tohoku region of Japan, 20km northeast to the center of Sendai, the capital city of the prefecture. The land area is 13.19km2, and the central part of the town forms a hill, radially sloping down to the seven beach areas separated by headlands. The communities around the beach areas were devastated by the GEJE. This study was part of a project called the Shichigahama Health Promotion Project, which was conducted in cooperation with Tohoku University and Shichigahama Town [11-15]. The project includes surveys to evaluate the health conditions and psychosocial aspects of the communities in the town severely affected by the GEJE and health promotion activities for the communities. This survey aimed to evaluate the current overall health and life status of all residents of the town whose houses were completely or significantly damaged, or all community members, of the five severely devastated coastal areas of Shichigahama town, where the earthquake and the resulting tsunami completely or significantly destroyed 10% of the houses. The definition of the “completely destroyed” and “significantly destroyed” criteria were based on the building damage assessment conducted by the Shichigahama government, following the criteria issued by the Cabinet Office. The survey teams visited all households in the target area to ask for participation in the survey in September 2012. An informed consent form and questionnaire were handed directly to residents willing to participate and were subsequently collected. The study protocol was reviewed and approved by the Ethics
Committee of Tohoku University Graduate School of Medicine [11-15].
2.1. Study population From the study population of 7,036 adults aged 20 years or older, 6,840 (97%) were contacted by the survey teams, and 4,949 (70%) of those subjects completed and returned the questionnaire with the written informed consent. We identified 3,966 (56%) participants who completed questions about experience of earthquake and tsunami disaster prevention before the GEJE. Only the subjects who were present in Shichigahama town during the GEJE outbreak (n = 2,314) were subjected to the following analyses.
2.2. Experience relevant to tsunami and earthquake disaster preparedness before the GEJE Disaster preparedness efforts before the GEJE were assessed with a question; “Before the GEJE, had you ever attended a lecture about earthquakes or tsunamis to prevent disasters at school or in the local community? Please choose all applicable experiences from the following five items: (i) Attending a lecture about earthquakes at school and/or in the community before the GEJE, (ii) Attending a lecture about tsunamis at school and/or in the community before the GEJE, (iii) Participating in earthquake drills at school and/or in the community before the GEJE, (iv) Participating in tsunami disaster drills at school and/or in the community before the GEJE, or (v) Hearing about past earthquakes or tsunamis from a family member or an acquaintance before the GEJE.”
2.3. Evacuation behavior after the onset of the GEJE Evacuation behaviors immediately after the onset of the GEJE were assessed by choosing one of the three
items: (i) I evacuated without any preparation, (ii) I evacuated after preparation, or (iii) I did not evacuate. It was designed to differentiate the subjects firstly whether they evacuated (i and ii) or not (iii). Secondly, the people who evacuated were further separated into the subcategories (i) and (ii), considering that the tsunami drills conducted before the GEJE usually advised residents to engage in quick preparations for taking along emergency items including medicinal drugs.
2.4. Other information The addresses of the locations where subjects stayed at the time of the GEJE onset and where their home located were collected, along with age and gender, considering whether they stayed within or outside the area inundated by the tsunami and whether they stayed at home or went out should affect the evacuation behavior. The Geospatial Information Authority of Japan reported the inundation area caused by the tsunami following the GEJE using a geographic information system (GIS) [20]. The addresses provided by the subjects were assigned to the geographic data outlining the inundation area of the town using ArcGIS (ERSI, Redlands, CA, US), and the subjects were classified into subpopulations who stayed inside or outside the tsunami-inundated area at the time of the onset. When the subjects reported that they stayed at home at the time of the earthquake or when the address they provided as their location at the time of the earthquake was the same as their home address, the subjects were classified as “at home at the time of the GEJE onset”. When the address of their location at the time of the GEJE onset and their home address were different, the subjects were classified as “away from home at the time of the GEJE onset”. Since employment status and basic social network status can be major confounding factors in participating in tsunami or disaster drills in advance and evacuation behaviors after a disaster, relevant information was collected. Social network status
was measured based on the Lubben Social Network Scale (LSNS)-6 and classified into “socially isolated (score < 12)” or “non-socially isolated (score ≥ 12)” [21]. Moreover, since a person’s physical condition can be a major confounding factor in participating in tsunami or earthquake drills in advance and evacuation behaviors after a disaster, time spent walking (< 0.5 hour/day or ≥ 0.5 hour/day) and active medical treatment for physical disease (absent or present) were collected.
2.5. Statistical analyses Multiple logistic regression analyses were conducted to evaluate the associations between experience relevant to the earthquake and tsunami disaster preparedness and evacuation behavior after the onset of the GEJE, adjusting for gender, age, employment, social networking, daily activity, and medical conditions as potential confounding factors. Further, a factor regarding whether the subjects stayed within the tsunami-inundated area at the time of the earthquake, and a factor regarding whether they stayed at home or went out at the time of the earthquake were also taken into the above consideration. The data were analyzed using SAS 9.4 (SAS Institute, Cary, NC, USA), with the significance set at p < 0.05. 3. Results Amongst the 2,314 subjects who completed the questionnaire (with socio-demographic characteristics summarized in Table 1), 32% had participated in school- or community-based tsunami drills, 37% had attended a school- or community-based lecture about tsunamis, 44% had participated in school- or community-based earthquake drills, 52% had attended a school- or community-based lecture about earthquakes, and 60% had heard about lessons from past tsunamis or earthquakes from a family member or an acquaintance. Older, more socially connected subjects or subjects who lived in tsunami-inundated areas
tended to have experienced tsunami preparedness activities before the GEJE, although these trends did not show statistical significance. A total of 1,560 subjects (67%) were evacuated after the onset of the earthquake. Subjects who had participated in school- or community-based tsunami drills showed a significantly higher rate of engaging in evacuation behavior than those who had not participated (multivariate adjusted OR [MOR] = 1.58, 95% confidence interval (CI) = 1.31 - 1.91, p < 0.01). Experience relevant to earthquake and tsunami disaster preparedness, other than tsunami drills, did not show any significant difference with respect to evacuation behaviors (MOR = 0.86 to 1.16) (Table 2). Because proximity to the seaside should affect evacuation behavior, whether the subjects stayed within or outside the tsunami-inundated area was taken into consideration when evaluating the association between experience relevant to earthquake and tsunami disaster preparedness and evacuation behavior after the onset of the GEJE. When only the subjects who stayed outside the tsunami-inundated area were subjected to the analysis, those who had participated in tsunami drills showed drastically higher evacuation rates (MOR = 4.49, CI = 2.73 -7.54, p < 0.01). In the analyses of subjects who stayed inside the tsunami-inundated area, those who had participated in tsunami drills also showed higher rates of engaging in evacuation behavior after the earthquake (MOR = 1.20), although the results were not significant (p = 0.44). Regardless of whether the subjects stayed within or outside the inundated area, there was no significant association between actual evacuation and preparedness efforts other than tsunami drills, i.e. participation in earthquake drills, attending lectures on tsunamis or earthquakes, or hearing lessons about past evacuations (Table 3). Whether subjects stayed at home or went out should also be taken into consideration in determining the association between experience relevant to earthquake and tsunami disaster preparedness and evacuation
behavior after onset of the GEJE. Amongst the subjects who stayed home, those who had participated in tsunami drills showed significant positive associations with evacuation behavior amongst populations both within and outside the tsunami inundated area, with MOR values of 3.46 (CI = 1.52 - 8.44, p < 0.01) and 3.76 (CI = 1.40 - 11.06, p = 0.01), respectively. Amongst those who went out, those who had participated in disaster drills also showed a significant positive association with evacuation behavior, although only in subjects whose homes were located outside the tsunami inundation area (MOR = 2.55, CI = 1.08 - 6.30, p = 0.04) (Table 4). Whether people evacuated with or without any preparation was evaluated with multivariate logistic regression analyses adjusted for potential confounding factors. The percentage of respondents who evacuated after preparation was significantly higher (11%) amongst the population who had participated in a tsunami drill before the event (MOR = 0.55, CI = 0.38 - 0.79, p < 0.01). Amongst the respondents who evacuated those with no experience of tsunami drill, 65% evacuated without any preparation, and 35% evacuated after preparation. In contrast amongst those who had participated in a tsunami drill, 54% evacuated without any preparation, and 46% evacuated after preparation (Table 5).
4. Discussion To our knowledge, this was the first epidemiological study to investigate the association between tsunami or earthquake drill participation and evacuation behavior. The current study provides initial evidence to endorse participation in tsunami drills in advance of catastrophes as a means of significantly facilitating evacuation behavior. The effect was more obvious for people who were relatively far from the seaside area and who may not see the necessity for evacuation from the tsunami. This finding was important because by the time
the risk of the tsunami is distinctly realized, it could be too late; thus, people must be trained to evacuate even when they do not perceive direct signs of risk. Immediately after onset of the GEJE, hazard warnings were continuously provided to residents around the tsunami-inundated area, and people should have evacuated regardless of having participated in tsunami drills. It is important to determine what motivated people outside the tsunami-inundated area, who were also potentially endangered, to evacuate. Our data indicate the effectiveness of tsunami drills in facilitating evacuation. Our study provides evidence indicating that the effect of the disaster drill facilitating evacuation behavior was more prominent amongst people who stayed at home at the time of the disaster onset, regardless of whether their home was located within or outside the tsunami-inundated area. Evacuation in the event of being away from home may require further consideration in tsunami drills. Evacuation in the event of being away from home might require further consideration in tsunami drills. Firstly, the surrounding situation should be less familiar, and less evacuation guidance and support from the family and neighboring residents may be expected. Secondly, when people would be in a workplace, they may need to follow the decision of the employer or the workplace. However, experience to participate workplace drills was not specifically evaluated in the current study. Workplace drills should be recommended together with special training for persons with specific responsibility for directing staff and employees in evacuation behavior. The decision to evacuate should not be in the hands of the employer or manager unless they were specifically trained and had designated responsibility. Amongst the subjects who were away from home at the time of the onset of the earthquake, tsunami drills were significantly effective only for those who stayed outside the tsunami-inundated area (p = 0.04). It may have been relatively uncertain for people who stayed outside of the inundated area whether they should
evacuate and to where they should evacuate unless they had been trained, while it may have been relatively apparent regarding the necessity and direction of evacuation for people who stayed within the inundated area. Participating in a tsunami drill in advance of the GEJE facilitated some residents to engage in preparation before the evacuation amongst the population who evacuated after onset of the GEJE. Tsunami drills conducted in communities usually advise residents to make quick preparations to bring emergency supplies with them, including medicinal drugs. In addition to the importance of tsunami drills in enabling safe evacuation to save participants’ lives, training for quick preparation for taking along essential supplies is also important for survivors to maintain their health and aid in their reconstruction of their post-disaster life environment. However, participating in earthquake drills, attending lectures on tsunamis or earthquakes, or hearing about past tsunamis or earthquakes from family members or acquaintances did not show significant effects. Thus, the data indicated that particularly tsunami drills, but not any of the other considered activities, are crucial to facilitating the evacuation behavior of people endangered by the tsunami. Our findings endorsed the purpose of implementing disaster drills in schools, workplaces, and local communities located in seaside areas worldwide to encourage endangered people to engage in evacuation behavior. The benefits of tsunami drills may be due to the nature of the program, which usually enables participants to increase their awareness of the risk and strategies for response by walking through the field, rather than merely obtaining information. Participants are also trained in interacting and collaborating with the surrounding people. The factors that make tsunami drills more effective must be further elucidated. Several limitations of this study must be addressed. First, the nature, quality, and frequency of the tsunami
drills were not taken into account in the current study. Whether the contents and frequency of drills have any effect on behavior should further be investigated to gather the evidence to make specific recommendations in regards to the efficacy of preparedness. Second, the term “evacuation” was not defined in the questionnaire. For example, one might have had planned to evacuate together with a family member who needed aids for evacuation and took a while to search him/her before leaving for the evacuation center. In the case, it is not certain whether the one may or may not have had considered the searching behavior as a part of the evacuation. The obscureness in the definition of evacuation may have had limited this study to understand the nature of behaviors of people affected by disasters. Defining evacuation behavior is essentially difficult but important issue which remains to be investigated further. Third, to what extent and how people should prepare essential supplies before evacuation also require further investigation. Fourth, in this study, the term “mijitaku” in Japanese was utilized for “preparation” in the sentences “(i) I evacuated without any preparation, and (ii) I evacuated after preparation” of the questionnaire. The term “mijitaku” in a context of evacuation obviously indicates preparation regarding emergency items and dresses to survive and did not include being sure of their family members or going to help others. The issues regarding being sure of their family members or going to help others are the important factors to cause a delay of evacuation, which also need to be taken into account. Fifth, the subject of this study should have included people themselves who needed special aids for evacuation or people who lived with family members who needed special aids. These factors might hinder the evacuation behavior and might have influenced the results of this study. The above factors to determine the effectiveness of conducting tsunami drills remain to be examined. In conclusion, the survey on the population who survived the GEJE provided the initial evidence to advocate
for the administration of tsunami drills in seaside communities to enhance evacuation behavior immediately after the disaster onset, in a situation that tsunami drill participation rates among seaside communities have not been satisfactory. Our findings indicate that the planning and execution of disaster drills to promote effective evacuation behavior is important in schools, workplaces, and municipalities.
Acknowledgements We thank the government of Shichigahama town and residents of the town who have supported and participated to the survey. This work was supported by the Reconstruction Agency, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and the Japan Agency for Medical Research and Development (AMED) through the Tohoku Medical Megabank Project, Ministry of Health, Labour and Welfare, Japan, through a Health Sciences Research Grant for Health Services [H24-Kenki-Shitei-002, H25-Kenki-Shitei-002 (Fukko)], the Japanese Society for the Promotion of Science (JSPS) through a Grant-in-Aid for Scientific Research (C) (No. 26350863), a Grant-in-Aid from the Kurokawa Cancer Research Foundation, and an Intramural Research Grant for Special Project Research from IRIDeS, Tohoku University, Japan. The authors declare no conflicts of interest.
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Figure 1. Location of the town of Shichigahama in Miyagi prefecture, Japan
Table 1. Categories of groups regarding experience relevant to earthquake and tsunami disaster preparedness before the Great East Japan Earthquake (The table extends toward the right) Experience relevant to earthquake and tsunami disaster preparedness
Heard about past earthquakes and tsunamis from a family member or an acquaintance
Attended lectures regarding tsunamis at school and/or in the community
Category of group
Not experienced
Experienced
Not experienced
Experienced
Number of subjects Age in years (%) 20–49 50–59
935
1,379
1,449
865
242 (26) 93 (10)
358 (26) 219 (16)
453 (31) 188 (13)
147 (17) 124 (14)
60–69 70+ Women (%)
222 (24) 378 (40) 535(57)
325 (24) 477 (35) 855(62)
316 (22) 492 (34) 914 (63)
Employment status (%) Employed 341 (36) 568 (41) 586 (40) Unemployed 553 (59) 760 (55) 808 (56) Unknown 41 (4) 51 (4) 55 (4) Social network status based on the Lubben Social Network Scale-6 (%) Socially isolated 233 (25) 263 (19) 346 (24) (score < 12) Socially connected 617 (66) 1,032 (75) 982 (69) (score ≥ 12) Unknown 85 (9) 84 (6) 121 (7) Time spent walking (%) < 0.5 hour/day ≥ 0.5 hour/day
287(31) 578 (62)
470 (34) 865 (63)
Unknown 70 (7) 44 (3) Undergoing medical treatment for physical diseases (%)*1 Absent 535 (57) 764 (55) Present 400 (43) 615 (45) Location at the time of the GEJE onset (%) Inside inundation area 404 (43) 667 (48) caused by the tsunami Outside inundation area 254 (27) 343 (25) caused by the tsunami Unknown
277 (30)
369 (27)
231 (27) 363 (42) 476 (55) 323 (37) 505 (58) 37 (4) 150 (17) 667 (77) 48 (6)
476 (33) 899 (62)
32 (32) 63 (63)
74 (5)
5 (5)
848 (59) 601 (41)
451 (52) 414 (48)
634 (44)
437 (51)
374 (26)
223 (26)
441 (30)
205 (24)
Table 1 continued Experience relevant to earthquake and tsunami disaster preparedness
Participated in tsunami disaster drills at school and/or in the community
Attended a lecture about earthquakes at school and/or in the community
Category of group
Not experienced
Experienced
Not experienced
Experienced
Number of subjects
1,581
733
1,121
1,193
503 (32) 214 (14) 337 (21) 527 (33) 957 (61)
97 (13) 98 (13) 210 (29) 328 (45) 433 (59)
336 (30) 141 (13) 243 (22) 401 (36) 698 (62)
264 (22) 171 (14) 304 (25) 454 (38) 692 (58)
637 (40)
272 (37)
442 (39)
467 (39)
Age in years (%) 20–49 50–59 60–69 70+ Women (%) Employment status (%) Employed
Unemployed 874 (55) 439 (60) 628 (56) Unknown 70 (4) 22 (3) 51 (5) Social network status based on the Lubben Social Network Scale-6 (%)
685 (57) 41 (3)
Socially isolated 393 (25) 103 (14) (score < 12) Socially connected 1,075 (68) 574 (78) (score ≥ 12) Unknown 113 (7) 56 (8) Time spent walking (%) < 0.5 hour/day 524 (33) 233 (32) ≥ 0.5 hour/day 972 (61) 471 (64) Unknown 85 (5) 29 (4) Undergoing medical treatment for physical diseases (%)*1
279 (25)
217 (18)
737 (66)
912 (76)
105 (9)
64 (5)
382 (34) 672 (60) 67 (6)
375 (31) 771 (65) 47 (4)
Absent 955 (60) Present 626 (40) Location at the time of the GEJE onset (%)
344 (47) 389 (53)
644 (57) 477 (43)
655 (55) 538 (45)
Inside inundation area caused by the tsunami Outside inundation area caused by the tsunami Unknown
630 (40)
441 (60)
513 (46)
558 (47)
447 (28)
150 (20)
275 (25)
322 (27)
504 (32)
142 (19)
333 (30)
313 (26)
(The table extends further toward the right)
Table 1 continued Experience relevant to earthquake and tsunami
Participated in earthquake drills at school and/or in the community
disaster preparedness Category of group
Not experienced
Experienced
Number of subjects Age in years (%) 20–49 50–59 60–69 70+ Women (%) Employment status (%)
1,280
1,034
387 (30) 171 (13) 248 (19) 474 (37) 739 (58)
213 (21) 141 (14) 299 (29) 381 (37) 651 (63)
Employed 510 (57) 399 (39) Unemployed 711 (40) 602 (58) Unknown 59 (3) 33 (3) Social network status based on Lubben Social Network Scale-6 (%) Socially isolated 338 (26) 158 (15) (score < 12) Social connected 834 (65) 815 (79) (score ≥ 12) Unknown 108 (8) 61 (6) Time spent walking (%) < 0.5 hour/day 448 (35) 309 (30) ≥ 0.5 hour/day 747 (58) 696 (67) Unknown 85 (7) 29 (3) Undergoing medical treatment for physical diseases (%)*1 Absent 768 (60) 531 (51) Present 512 (40) 503 (49) Location at the time of the GEJE outbreak (%) Inside tsunami-inundated 537 (42) 534 (52) area Outside 334 (26) 263 (25) tsunami-inundated area Unknown
409 (32)
237 (23)
Study participants were classified whether they had experienced any of the five experience relevant to earthquake and tsunami disaster preparedness listed in the top row before the Great East Japan Earthquake (GEJE) (n = 2,314). Characteristics of each group regarding disaster preparedness before the GEJE are summarized regarding age, gender, employment status, social network status, time spent walking, physical health condition and location at the time of the GEJE onset. *1 “physical diseases” include stroke,
myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia. Table 2. The effect of each experience relevant to earthquake and tsunami disaster preparedness before the Great East Japan Earthquake (GEJE) on evacuation after the GEJE onset Category of group regarding each experience relevant to earthquake and tsunami disaster preparedness before the GEJE
Not experienced
Experienced
Heard about past earthquakes and tsunamis from a family member or an acquaintance Number of subjects who evacuated 608 / 935 952 / 1,379 / Number of total subjects 65 69 Percentage of subjects who evacuated 1.0 (Ref.) 1.06 (0.87 – 1.29) Multivariate adjusted OR (95% CI)
p-value
0.58
Attended a lecture about tsunamis at school and/or in the community Number of subjects who evacuated / Number of total subjects
956 / 1,449
604 / 865
Percentage of subjects who evacuated
66
70
Multivariate adjusted OR (95% CI)
1.0 (Ref.)
0.88 (0.68 – 1.13)
0.30
Participating in tsunami drills at school and/or in the community Number of subjects who evacuated / Number of total subjects
986 / 1,581
574 / 733
Percentage of subjects who evacuated
62
78
Multivariate adjusted OR (95% CI)
1.0 (Ref.)
1.99 (1.53 – 2.61)
<0.01
Attending a lecture about earthquakes at school and/or in the community Number of subjects who evacuated / Number of total subjects Percentage of subjects who evacuated
740 / 1,121
820 / 1,193
66
69
1.0 (Ref.) Multivariate adjusted OR (95% CI) Participated in earthquake drills at school and/or in the community Number of subjects who evacuated 831 / 1,280 / Number of total subjects 65 Percentage of subjects who evacuated 1.0 (Ref.) Multivariate adjusted OR (95% CI)
1.16 (0.93 – 1.45)
0.20
729 / 1,034 71 0.86 (0.68 – 1.08)
0.18
Multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had experienced each of the five experiences relevant to earthquake and tsunami disaster preparedness before the GEJE to the one among people who had not are shown in the table (n = 2,314). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown); and experiences relevant to earthquake and tsunami disaster
preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia. Table 3. The effect of each tsunami disaster preparedness effort before the Great East Japan Earthquake on the evacuation behavior of subjects who stayed inside or outside the tsunami-inundated area at the time of the onset Category of group regarding each experience relevant to earthquake and tsunami disaster preparedness before the GEJE
Not experienced
Experienced
Number of subjects who evacuated / Number of total subjects (%)
Number of subjects who evacuated / Number of total subjects (%)
ORs
ORs (95% CIs)
Heard about past earthquakes and tsunami from a family member or an acquaintance 340 / 404 1.0 569 / 667 1.01 Inside tsunamiinundated area (84) (Ref.) (85) (0.70 – 1.43) Outside tsunamiinundated area
94 / 254 (37)
1.0 (Ref.)
163 / 343 (48)
1.36 (0.94 – 1.95)
p-value
0.98 0.10
Attended a lecture about tsunamis at school and/or in the community 377 / 437 86 102 / 223 (46)
1.01 (0.64 – 1.60) 0.64 (0.40 – 1.01)
Participated in tsunami drills at school and/or in the community 525 / 630 1.0 384 / 441 Inside tsunamiinundated area (83) (Ref.) (87) 162 / 447 1.0 95 / 150 Outside tsunamiinundated area (36) (Ref.) (63)
1.20 (0.77 – 1.88) 4.49 (2.73 – 7.54)
Inside tsunamiinundated area Outside tsunamiinundated area
532 / 634 (84) 155 / 374 (41)
1.0 (Ref.) 1.0 (Ref.)
0.97 0.06
0.44 <0.01
After stratification of the subjects into two groups; subjects who stayed inside or outside the tsunami-inundated area at the time of the Great East Japan Earthquake (GEJE) onset, multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had experienced each of the three experiences relevant to earthquake and tsunami disaster preparedness before the GEJE to the one among people who had not are shown in the table (n = 1,668). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown); and experience relevant to earthquake and tsunami disaster preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia.
Table 4. The effect of experience of tsunami drill before the Great East Japan Earthquake on the evacuation behavior of subjects who stayed at home or not at the time of the onset No tsunami drill participation before the GEJE
Category of group regarding experience Number of subjects of tsunami drill before who evacuated / Number of total the GEJE subjects (%)
ORs
At home at the time of the GEJE onset (n = 763) 317 / 361 Inside tsunami1.0 (Ref.) inundated area (88) Outside tsunamiinundated area
60 / 109 (55)
1.0 (Ref.)
Trained with tsunami drill before the GEJE Number of subjects who evacuated / Number of total subjects (%)
ORs (95% CIs)
237 / 247 (96)
3.46 (1.52 – 8.44)
<0.01
36 / 46 (78)
3.76 (1.40 – 11.06)
0.01
48 / 56 (85) 48 / 74 (65)
0.70 (0.11 – 4.03) 2.55 (1.08 – 6.30)
p-value
Not at home at the time of the GEJE onset (n = 298) Inside tsunamiinundated area Outside tsunamiinundated area
63 / 74 (85) 49 / 94 (52)
1.0 (Ref.) 1.0 (Ref.)
0.69 0.04
After stratification of the subjects into the groups; subjects who stayed at home or not at the time of the onset of the Great East Japan Earthquake (GEJE), and for each of the subgroups, subjects who stayed inside or outside tsunami-inundated area at the time, multivariate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of proportion of subjects who evacuated right after onset of the Great East Japan Earthquake (GEJE) among people who had participated tsunami drills before the GEJE to the one among people who had not are shown in the table (n = 1,061). The ORs are adjusted for gender; age in years (20–49, 50–59, 60–69, 70+); job (employed, unemployed, unknown); social network status based on the Lubben Social Network Scale-6 [social isolation (score < 12), without social isolation (score ≥ 12), unknown]; time spent walking (< 0.5 hour/day, ≥ 0.5 hour/day, unknown); undergoing medical treatment for physical diseases*1 (absent, present); locations where the subject was at the time of the GEJE onset (inside or outside tsunami inundation area, unknown) ; and experience relevant to earthquake and tsunami disaster preparedness before the GEJE. *1 “physical diseases” include stroke, myocardial infarction or angina, cancer, kidney disease, liver disease, hypertension, diabetes mellitus, or hyperlipidaemia.
Table 5. Experience of tsunami drills before the Great East Japan Earthquake and whether people evacuated with or without preparation Number of subjects who
Number of subjects who
evacuated without preparation
evacuated after preparation
Total
Number of subjects with no experience of tsunami drills before the GEJE
342 (65%)
183 (35%)
525 (100%)
Number of subjects who had participated in tsunami drills before the GEJE
208 (54%)
176 (46%)
384 (100%)
Amongst the 525 subjects who had no experience participating in a tsunami drill before the GEJE and evacuated after the event, 342 (65.1%) evacuated without any preparation and 183 (34.9%) evacuated after preparation. Amongst the 384 subjects who had participated in a tsunami drill before the GEJE and evacuated after the event, 208 (54.2%) evacuated without any preparation and 176 (45.8%) evacuated after preparation.
Highlights The evacuation rate was significantly higher among participants of tsunami drills.
Other experience of earthquake and tsunami disaster prevention did not affect evacuation behaviors.
The study provides initial evidence to advocate administration of tsunami drills.