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Frostquakes in New England
Engineering Geology 56 (2000) 389–394 www.elsevier.nl/locate/enggeo
Opinion paper
Frostquakes in New England Patrick J. Barosh * P.J. Barosh and Associates, 35 Potter Street, Concord, MA 01742, USA Accepted 17 May 1999
Abstract Frostquakes are generated by tensional fracturing of the ground due to relatively rapid freezing. They are often accompanied by explosive noise and may reach Intensity V effects, yet they are only felt in neighborhoods and are not recorded on seismic networks. Frostquakes may crack macadam, concrete slabs, shallow soil pipe and some foundation materials along the line of the fracture. They occur in the early hours of the morning in mid-winter during major cold snaps. The ones investigated occurred in glacial sand and silt and none were found on till or bedrock. The recognition of frostquakes is important in correcting the records for fault-caused earthquakes. Frostquakes in the historic record complicate the difficulty of predicting large earthquakes from small ones. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Cryoseism; Frostquake; Seismotectonic studies; Tensional fracturing
1. Frostquakes, present and past A loud bang and shaking awakened the residents of a neighborhood in Randolph, Massachusetts, south of Boston, about a quarter after five in the morning on January 2, 1999. (Fig. 1). Between 30 and 40 people from an area a quarter by half a mile in size called the police and many rushed outside on this very cold morning. The sound, similar to thunder or an explosion, and shaking were described to a local reporter
* Fax: 1-401-254-2095. E-mail address: [email protected] (P. Barosh)
(Crowley, 1997). There seems to have been four distinct tremors in a series. ‘‘The whole house shook. Pictures were shaking and some were knocked over’’. Glasses in cupboards and the windows rattled, and car alarms were set off. Next came the discussion whether it was caused by an earthquake or an explosion; perhaps methane at a nearby landfill or a gas line leak was set off . It was neither — these are the effects of a typical frostquake. Incidences of very local ground breakage due to freezing, accompanied by noises and shaking of the ground, are informally referred to as frostquakes and more formally as cryoseisms. They appear to be produced when relatively mild winter temperatures are interrupted by sudden drastic temperature drops when there is little or no insulat-
0013-7952/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0 0 1 3 -7 9 5 2 ( 9 9 ) 0 0 09 2 - 7
390
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 1. Index map of New England showing locations of known and apparent frostquakes.
ing snow cover on the ground. This produces a too rapid and deep freezing of the ground for the soil to adjust normally to the resulting contraction and it cracks open. The ‘snap’ is heard and felt. It is a model earthquake analogous to movement on a fault, but here the causative force is freezing. The zero focal depth results in relatively high surface waves which die out rapidly with no filtering out of the audible waves. The relation of frostquakes with ground cracks is commonly not recognized because they are not looked for or are covered by falling or drifting snow. The ones recognized are usually those cutting bare road pavement. It is also likely that many frost cracks which cross country roads formed with quakes which no one felt or noticed. Frostquakes occur from time to time in the northern United States when weather conditions are favorable, and several have been investigated in New England (Barosh and Smith, 1979, 1982). They are not recorded by seismic networks, except in very unusual circumstances, and generally have
a mysterious air about them. In the past the smell of brimstone, and now signs of the impending apocalypse, are commonly mentioned by those interviewed. They can be traumatic for those rudely awakened and remembered vividly after 75 years. Frostquakes are probably less likely to be recognized for what they are now than in the 19th century, because of the more mobile urbanized population which is less in touch with the land. It is important to recognize frostquakes in seismotectonic studies, especially in the northeast and north-central United States as they can muddy the record of tectonic movements, just as explosions and mine collapses do. Some have even been described as examples of active faulting. Reports of isolated Modified Mercalli Intensity IV–V events in the United States and small offsets of Pleistocene surfaces or deposits need to be investigated with this in mind. Surface rupture was reported along a northeasttrending fault between Attleboro and Whitman, Massachusetts ( Fig. 1) during an earthquake in
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 2. Sketch map of an area in Whitman, MA showing the approximate location of cracks associated with frostquake in January, 1903.
January of 1903 by H.F. Reid, who later originated the elastic rebound theory of earthquakes after the San Francisco earthquake of 1906. This was investigated in 1978 in a study of reported recent fault offsets in the northeastern United States. It was possible to reconstruct the position of the surface fracture in Whitman (Fig. 2) and to track down and interview someone who had experienced the shaking. The ground movement and alarm placed the earthquake in the Intensity V category. Two cracks formed, with the longest extending across the ice of a nearby pond. There were no vertical offsets of the crack, just a gap 2 cm or less which
391
extended downward for about 1 m. The effects at Attleboro were less, but still reached Intensity IV. It was then discovered that the events at these two towns were separated by a day. Thus, there was no southeastern Massachusetts earthquake, but two different neighborhood events. At least one person thought at the time that they were due to frost in the ground. At this point in the study, a series of frostquakes occurred in New England and the similarities verified that freezing, rather than tectonic forces, caused these events. Unusual weather conditions during February 1979, produced a number of frostquakes with associated ground cracking in New England ( Fig. 1). The ‘quakes’ occurred during a two-day time span between northeastern Massachusetts and central Maine, when temperatures dropped abruptly from above freezing to −20 to −30°C. They generally occurred just before dawn and awakened residents in the affected areas. The tremors were compared to furnace explosions, cars driving into the side of a house or strong sonic booms. None of them, however, was recorded by the Northeastern U.S. Seismograph Network. The effects felt were quite local and probably restricted to a few tens of acres. One to five irregular ground fractures 0.5 cm wide from a few to 100 m long were produced (Figs. 3–5). The observed fractures cut through sand, silt and fine gravel of glacial outwash and lake beds. Some also broke through macadam roads and, in one case, a 15+ cm thick concrete slab (Figs. 6 and 7). Frostquakes, thus, can produce minor, very localized damage to man-made structures. Concrete slabs or shallow buried concrete or clay pipe could be cracked, in addition to foundations. Roads appear especially sensitive to cracking ( Fig. 3). Frostquakes would not be likely to produce damage to structures with foundations in bedrock. Similar freezing conditions may also augment the effects from tectonic earthquakes. The Miramichi, New Brunswick earthquake of January 9, 1982 coincided with an unusual drop in temperature which was reported to have frozen the ground to a depth of 2.3 m at Caribou, Maine. The amount of ground cracking in eastern Maine
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P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 3. Sketch map of an area along Cranberry Road, Townsend, MA showing cracks formed during a frostquake in February, 1979.
appeared excessive in regards to the other effects, especially across roads (Barosh, 1983). In one case where a crack extended beneath a building from a roadway, the window above it was cracked. This excess cracking appears due to seismic motion on ground already under considerable tension. Ancient filled cracks similar to those producing frostquakes cut Late Pleistocene sand locally in southern New England and may have formed the same way. Such cracking was probably more common in the past, under cooler conditions than today, and was related to the initial formation of some types of pattern ground. Iron-stained ancient cracks cutting Late Pleistocene sand and silt deposits may have formed with paleo-frostquakes (Fig. 8). Repeated freezing of water and consequent expansion may have formed ice wedges (Stone et al., 1992) and their intersections form patterned ground. The materials in which these cracks are found are the same as those of the modern cracks.
2. Conclusions Frostquakes are an interesting phenomena reported at times in New England, New York and Pennsylvania, although not always recognized as such. Some scattered events in the pre-instrumental record may also be, if the descriptions match. Frostquakes result from relatively rapid freezing of the ground creating sufficient tension to split the ground open. The resulting seismic waves may produce loud noises and cause up to Intensity V effects, but attenuate rapidly and only affect neighborhoods. Very minor structural damage may result and frostquakes provide the background level for seismic effects in northern areas. They occur in the early hours of the morning in January and February. Likely times of their occurrence could be predicted from weather records and precise forecasts, but not the location. Unrecognized frostquakes can pose problems for assigning hazards from earthquakes.
P.J. Barosh / Engineering Geology 56 (2000) 389–394
393
Fig. 4. Ice crack in bare ground at Townsend, MA formed in February, 1979 — the 6 in rule gives the scale.
Fig. 6. Ice crack through a 15+ cm concrete porch (18 months old ) in Pepperell, MA formed in February, 1979.
Fig. 5. Ice crack through a thin crust of snow at Epsom, NH formed on February, 1979 — the 6 in rule gives the scale.
Fig. 7. Ice crack leading eastward from the concrete porch ( Figs. 3 and 6) across the yard (with snow brushed away) in Pepperell, MA — the dog shows the scale.
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P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 8. Late Pleistocene iron-stained crack in deltaic glacial sand and silt in North Brookfield, MA.
References Barosh, P.J., 1983. Effects of the Miramichi earthquake in northern Maine and adjacent New Brunswick. In: Stevens, A.E. ( Ed.), Miramichi (New Brunswick, Canada) Earthquake Sequence of 1982. Earthquake Engineering Research Institute, pp. 75–85. Barosh, P.J., Smith, P.V., 1979. Frostquakes and associated ground breakage in New England. Earthquake Notes 50 (3), 12 and Seismological Soc. America Eastern Section, Ann. Meeting, Blacksburg, VA; Abs. with program. Frostquakes and associated ground breakage in New England. In: Barosh, P.J., Smith, P.V. (Eds.), New England Seismo-
tectonic Study Activities During Fiscal Year 1980 1982. U.S. Nuclear Regulatory Commission Report, pp. 32–35. NUREG/CR-3252. Crowley, E.W., 1997. Mysterious tremors shake up Randolph. The Patriot Ledger. Quincy, MA. Stone, B.D., Lapham, W.L., Larson, F.D., 1992. Glaciation of the Worcester plateau, Ware-Barre area, and evidence for the succeeding Late Woodfordian periglacial climate. In: Robinson, P., Brady, J.B. (Eds.), New England Intercollegiate Geological Conference, 84th Annual Meeting, University of Massachusetts, Department of Geology and Geography, Guidebook for field trips in the Connecticut Valley region of Massachusetts and adjacent states, 467–487.
Opinion paper
Frostquakes in New England Patrick J. Barosh * P.J. Barosh and Associates, 35 Potter Street, Concord, MA 01742, USA Accepted 17 May 1999
Abstract Frostquakes are generated by tensional fracturing of the ground due to relatively rapid freezing. They are often accompanied by explosive noise and may reach Intensity V effects, yet they are only felt in neighborhoods and are not recorded on seismic networks. Frostquakes may crack macadam, concrete slabs, shallow soil pipe and some foundation materials along the line of the fracture. They occur in the early hours of the morning in mid-winter during major cold snaps. The ones investigated occurred in glacial sand and silt and none were found on till or bedrock. The recognition of frostquakes is important in correcting the records for fault-caused earthquakes. Frostquakes in the historic record complicate the difficulty of predicting large earthquakes from small ones. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Cryoseism; Frostquake; Seismotectonic studies; Tensional fracturing
1. Frostquakes, present and past A loud bang and shaking awakened the residents of a neighborhood in Randolph, Massachusetts, south of Boston, about a quarter after five in the morning on January 2, 1999. (Fig. 1). Between 30 and 40 people from an area a quarter by half a mile in size called the police and many rushed outside on this very cold morning. The sound, similar to thunder or an explosion, and shaking were described to a local reporter
* Fax: 1-401-254-2095. E-mail address: [email protected] (P. Barosh)
(Crowley, 1997). There seems to have been four distinct tremors in a series. ‘‘The whole house shook. Pictures were shaking and some were knocked over’’. Glasses in cupboards and the windows rattled, and car alarms were set off. Next came the discussion whether it was caused by an earthquake or an explosion; perhaps methane at a nearby landfill or a gas line leak was set off . It was neither — these are the effects of a typical frostquake. Incidences of very local ground breakage due to freezing, accompanied by noises and shaking of the ground, are informally referred to as frostquakes and more formally as cryoseisms. They appear to be produced when relatively mild winter temperatures are interrupted by sudden drastic temperature drops when there is little or no insulat-
0013-7952/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S0 0 1 3 -7 9 5 2 ( 9 9 ) 0 0 09 2 - 7
390
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 1. Index map of New England showing locations of known and apparent frostquakes.
ing snow cover on the ground. This produces a too rapid and deep freezing of the ground for the soil to adjust normally to the resulting contraction and it cracks open. The ‘snap’ is heard and felt. It is a model earthquake analogous to movement on a fault, but here the causative force is freezing. The zero focal depth results in relatively high surface waves which die out rapidly with no filtering out of the audible waves. The relation of frostquakes with ground cracks is commonly not recognized because they are not looked for or are covered by falling or drifting snow. The ones recognized are usually those cutting bare road pavement. It is also likely that many frost cracks which cross country roads formed with quakes which no one felt or noticed. Frostquakes occur from time to time in the northern United States when weather conditions are favorable, and several have been investigated in New England (Barosh and Smith, 1979, 1982). They are not recorded by seismic networks, except in very unusual circumstances, and generally have
a mysterious air about them. In the past the smell of brimstone, and now signs of the impending apocalypse, are commonly mentioned by those interviewed. They can be traumatic for those rudely awakened and remembered vividly after 75 years. Frostquakes are probably less likely to be recognized for what they are now than in the 19th century, because of the more mobile urbanized population which is less in touch with the land. It is important to recognize frostquakes in seismotectonic studies, especially in the northeast and north-central United States as they can muddy the record of tectonic movements, just as explosions and mine collapses do. Some have even been described as examples of active faulting. Reports of isolated Modified Mercalli Intensity IV–V events in the United States and small offsets of Pleistocene surfaces or deposits need to be investigated with this in mind. Surface rupture was reported along a northeasttrending fault between Attleboro and Whitman, Massachusetts ( Fig. 1) during an earthquake in
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 2. Sketch map of an area in Whitman, MA showing the approximate location of cracks associated with frostquake in January, 1903.
January of 1903 by H.F. Reid, who later originated the elastic rebound theory of earthquakes after the San Francisco earthquake of 1906. This was investigated in 1978 in a study of reported recent fault offsets in the northeastern United States. It was possible to reconstruct the position of the surface fracture in Whitman (Fig. 2) and to track down and interview someone who had experienced the shaking. The ground movement and alarm placed the earthquake in the Intensity V category. Two cracks formed, with the longest extending across the ice of a nearby pond. There were no vertical offsets of the crack, just a gap 2 cm or less which
391
extended downward for about 1 m. The effects at Attleboro were less, but still reached Intensity IV. It was then discovered that the events at these two towns were separated by a day. Thus, there was no southeastern Massachusetts earthquake, but two different neighborhood events. At least one person thought at the time that they were due to frost in the ground. At this point in the study, a series of frostquakes occurred in New England and the similarities verified that freezing, rather than tectonic forces, caused these events. Unusual weather conditions during February 1979, produced a number of frostquakes with associated ground cracking in New England ( Fig. 1). The ‘quakes’ occurred during a two-day time span between northeastern Massachusetts and central Maine, when temperatures dropped abruptly from above freezing to −20 to −30°C. They generally occurred just before dawn and awakened residents in the affected areas. The tremors were compared to furnace explosions, cars driving into the side of a house or strong sonic booms. None of them, however, was recorded by the Northeastern U.S. Seismograph Network. The effects felt were quite local and probably restricted to a few tens of acres. One to five irregular ground fractures 0.5 cm wide from a few to 100 m long were produced (Figs. 3–5). The observed fractures cut through sand, silt and fine gravel of glacial outwash and lake beds. Some also broke through macadam roads and, in one case, a 15+ cm thick concrete slab (Figs. 6 and 7). Frostquakes, thus, can produce minor, very localized damage to man-made structures. Concrete slabs or shallow buried concrete or clay pipe could be cracked, in addition to foundations. Roads appear especially sensitive to cracking ( Fig. 3). Frostquakes would not be likely to produce damage to structures with foundations in bedrock. Similar freezing conditions may also augment the effects from tectonic earthquakes. The Miramichi, New Brunswick earthquake of January 9, 1982 coincided with an unusual drop in temperature which was reported to have frozen the ground to a depth of 2.3 m at Caribou, Maine. The amount of ground cracking in eastern Maine
392
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 3. Sketch map of an area along Cranberry Road, Townsend, MA showing cracks formed during a frostquake in February, 1979.
appeared excessive in regards to the other effects, especially across roads (Barosh, 1983). In one case where a crack extended beneath a building from a roadway, the window above it was cracked. This excess cracking appears due to seismic motion on ground already under considerable tension. Ancient filled cracks similar to those producing frostquakes cut Late Pleistocene sand locally in southern New England and may have formed the same way. Such cracking was probably more common in the past, under cooler conditions than today, and was related to the initial formation of some types of pattern ground. Iron-stained ancient cracks cutting Late Pleistocene sand and silt deposits may have formed with paleo-frostquakes (Fig. 8). Repeated freezing of water and consequent expansion may have formed ice wedges (Stone et al., 1992) and their intersections form patterned ground. The materials in which these cracks are found are the same as those of the modern cracks.
2. Conclusions Frostquakes are an interesting phenomena reported at times in New England, New York and Pennsylvania, although not always recognized as such. Some scattered events in the pre-instrumental record may also be, if the descriptions match. Frostquakes result from relatively rapid freezing of the ground creating sufficient tension to split the ground open. The resulting seismic waves may produce loud noises and cause up to Intensity V effects, but attenuate rapidly and only affect neighborhoods. Very minor structural damage may result and frostquakes provide the background level for seismic effects in northern areas. They occur in the early hours of the morning in January and February. Likely times of their occurrence could be predicted from weather records and precise forecasts, but not the location. Unrecognized frostquakes can pose problems for assigning hazards from earthquakes.
P.J. Barosh / Engineering Geology 56 (2000) 389–394
393
Fig. 4. Ice crack in bare ground at Townsend, MA formed in February, 1979 — the 6 in rule gives the scale.
Fig. 6. Ice crack through a 15+ cm concrete porch (18 months old ) in Pepperell, MA formed in February, 1979.
Fig. 5. Ice crack through a thin crust of snow at Epsom, NH formed on February, 1979 — the 6 in rule gives the scale.
Fig. 7. Ice crack leading eastward from the concrete porch ( Figs. 3 and 6) across the yard (with snow brushed away) in Pepperell, MA — the dog shows the scale.
394
P.J. Barosh / Engineering Geology 56 (2000) 389–394
Fig. 8. Late Pleistocene iron-stained crack in deltaic glacial sand and silt in North Brookfield, MA.
References Barosh, P.J., 1983. Effects of the Miramichi earthquake in northern Maine and adjacent New Brunswick. In: Stevens, A.E. ( Ed.), Miramichi (New Brunswick, Canada) Earthquake Sequence of 1982. Earthquake Engineering Research Institute, pp. 75–85. Barosh, P.J., Smith, P.V., 1979. Frostquakes and associated ground breakage in New England. Earthquake Notes 50 (3), 12 and Seismological Soc. America Eastern Section, Ann. Meeting, Blacksburg, VA; Abs. with program. Frostquakes and associated ground breakage in New England. In: Barosh, P.J., Smith, P.V. (Eds.), New England Seismo-
tectonic Study Activities During Fiscal Year 1980 1982. U.S. Nuclear Regulatory Commission Report, pp. 32–35. NUREG/CR-3252. Crowley, E.W., 1997. Mysterious tremors shake up Randolph. The Patriot Ledger. Quincy, MA. Stone, B.D., Lapham, W.L., Larson, F.D., 1992. Glaciation of the Worcester plateau, Ware-Barre area, and evidence for the succeeding Late Woodfordian periglacial climate. In: Robinson, P., Brady, J.B. (Eds.), New England Intercollegiate Geological Conference, 84th Annual Meeting, University of Massachusetts, Department of Geology and Geography, Guidebook for field trips in the Connecticut Valley region of Massachusetts and adjacent states, 467–487.