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Microearthquakes and seismotectonic analysis for a nuclear plant area in southeastern Finland
207A influenced by the spatial extent of the deposited layer. Trapezoidal (including triangular and rectangular) rills are considered. Equations are developed for transport-limited and entrainment-limited cases. The model adequately describes results of experiments by Meyer and Harmon (1985). 924015 Engineering geological zonation of Xiamen granitic weathered crust and bearing capacity of residual soil Guolin, R; Yushan, L
Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990 V3, P1989-1995. Publ Rotterdam: A A Balkema, 1990 A classification system for weathered granitic rocks is described. The weathered zone (subdivided into slightly, moderately, and highly weathered) is followed by an irregularly weathered zone with varying proportions of rock and residual soils, then a final residual soil zone of mottled conglomerate, mottled clay, and red clay soils. Correlations between the classification and point load, compressive strength, and wave velocity values and between SPT N count and bearing capacity are examined.
Earthquake mechanisms and effects 924016 Site response of two rock and soil station pairs to strong and weak ground motion Darragh, R B; Shakal, A F Bull Seismol Soc Am 11"81.N5. Oct 1991, P1885-1899
Dependence of ground motion on site conditions is well documented. Data recorded at two sets of rock and soil pairs in California are presented. One pair is soft soil/sandstone and shale, the other stiff soil/sandstone. Amplification at the sites was evaluated over a range of frequencies and earthquake magnitudes. At the soft soil site the amplification appears to increase as magnitude (recorded at the rock site) decreases. This effect was not seen at the stiff soil site. Results help define the range of subsurface conditions and ground motion for which techniques to predict effects of major events from recordings of smaller ones are applicable. 924017 Loading faults to failure. Short note Sibson, R H Bull Seismol Soc Am Vgl, N6. Dec 1991, P2493-2497 The representation of frictional instability responsible for shallow earthquakes in terms of simple, spring loaded block-slider models is questioned. Dependence of normal stress on shear stress and time dependence of frictional shear strength on pore fluid migration are discussed. Fluid flux may change and affect regularity of recurrence. Contrasting changes in shear strength during loading cycles may result in different pre- and postfailure behaviours for normal and thrust faults, possibly reflected in foreshock and aftershock patterns. 924018 Soil amplification based on seismometer array and microtremor observations in Chiba, Japan Lu, L; Yamazaki, F; Katayama, T Earthq Engog Struct Dynam V21, N2, Feb 1992, P95-108
Local site conditions can significantly influence the characteristics of earthquake ground motion. Amplification characteristics are investigated in terms of peak ground acceleration and transfer function using data from the Chiba array. Amplification of peak ground acceleration occurred in the top, soft layer and was similar for all three components. Effects of nonlinear
response of the soil deposits on transfer function are examined. Power spectra and spatial coherency of microtremors and earthquakes are compared. 924019 Space-time distribution patterns of destructive earthquakes in the inner belt of central Japan: activity intervals and locations of earthquakes Kanaori, Y; Kawakami, S; Yairi, K Engng Geol V31, N3/4, Dec 1991, P209-230
The space-time relation between epicentres of destructive large earthquakes (magnitude M (JMA) above 6.4) in the inner central belt of Japan has been analysed considering the block boundaries defined by Kanaori et al (1990). Space-time patterns are examined for each boundary and indicate periodic activity with the present time being an active period. Five regions having no earthquakes (seismic gaps) in the present active period are identified. Earthquakes of magnitude about 7 can be expected in the seismic gaps in the near future. Prediction of damaging earthquakes and seismic risk evaluation are discussed. 924020 Microearthquakes and seismotectonic analysis for a nuclear plant area in southeastern Finland Saari, J Engng Geol V31, N3/4, Dec 1991, P231-247
Seismicity of Precambrian Rapakivi Granite in an area of radius 100km around the Loviisa area has been studied. A local microearthquake monitoring network recorded 29 micro- and ultra-microearthquakes over a 6 year period. The events identify active faults in the area. Source parameters computed using a simple circular source model give peak slip less than 2.25mm, stress drops less than 0.2MPa, and source radii generally less than 50m. Earthquake depths were less than 5km. Peak slip values are discussed with reference to seismotectonic implications. 924021 Fractal features of the earthquake mechanism and a simple mechanical model Matsuzaki, M; Takayasu, H J Geophys Res V96, NB12, Nov 1991. P19925-19931
A simple model allowing easier understanding of the physical mechanisms of earthquakes than cellular automaton models is presented. The two dimensional stick-slip system displays dynamic order-disorder phase transition with a control parameter proportional to the strength of interaction. It can explain fractal features in seismicity, the locality of real earthquakes, and that local magnitude distributions deviate from the power law Gutenburg-Richter relation. 924022 Probabilistic assessment of earthquake hazard in Vietnam based on seismotectonic regionalization Phuong, N H Tectonophysies F198, NI, Nov 1991, P81-93
The theory of extreme values is applied to earthquake source zones in Vietnam using the first and third Gumbel distributions. The earthquake record from 1903-1988 is used. Mean return periods are calculated for earthquakes of different values together with probabilities of occurrence within a set period. The largest earthquake (Mmax = 7) is predicted for the Ma source zone within a return period of 123 years. A magnitude 6 event is predicted with 90% probability of occurrence for the north with 50 years, whilst for the south the magnitude and probability are 5 and 80% respectively.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990 V3, P1989-1995. Publ Rotterdam: A A Balkema, 1990 A classification system for weathered granitic rocks is described. The weathered zone (subdivided into slightly, moderately, and highly weathered) is followed by an irregularly weathered zone with varying proportions of rock and residual soils, then a final residual soil zone of mottled conglomerate, mottled clay, and red clay soils. Correlations between the classification and point load, compressive strength, and wave velocity values and between SPT N count and bearing capacity are examined.
Earthquake mechanisms and effects 924016 Site response of two rock and soil station pairs to strong and weak ground motion Darragh, R B; Shakal, A F Bull Seismol Soc Am 11"81.N5. Oct 1991, P1885-1899
Dependence of ground motion on site conditions is well documented. Data recorded at two sets of rock and soil pairs in California are presented. One pair is soft soil/sandstone and shale, the other stiff soil/sandstone. Amplification at the sites was evaluated over a range of frequencies and earthquake magnitudes. At the soft soil site the amplification appears to increase as magnitude (recorded at the rock site) decreases. This effect was not seen at the stiff soil site. Results help define the range of subsurface conditions and ground motion for which techniques to predict effects of major events from recordings of smaller ones are applicable. 924017 Loading faults to failure. Short note Sibson, R H Bull Seismol Soc Am Vgl, N6. Dec 1991, P2493-2497 The representation of frictional instability responsible for shallow earthquakes in terms of simple, spring loaded block-slider models is questioned. Dependence of normal stress on shear stress and time dependence of frictional shear strength on pore fluid migration are discussed. Fluid flux may change and affect regularity of recurrence. Contrasting changes in shear strength during loading cycles may result in different pre- and postfailure behaviours for normal and thrust faults, possibly reflected in foreshock and aftershock patterns. 924018 Soil amplification based on seismometer array and microtremor observations in Chiba, Japan Lu, L; Yamazaki, F; Katayama, T Earthq Engog Struct Dynam V21, N2, Feb 1992, P95-108
Local site conditions can significantly influence the characteristics of earthquake ground motion. Amplification characteristics are investigated in terms of peak ground acceleration and transfer function using data from the Chiba array. Amplification of peak ground acceleration occurred in the top, soft layer and was similar for all three components. Effects of nonlinear
response of the soil deposits on transfer function are examined. Power spectra and spatial coherency of microtremors and earthquakes are compared. 924019 Space-time distribution patterns of destructive earthquakes in the inner belt of central Japan: activity intervals and locations of earthquakes Kanaori, Y; Kawakami, S; Yairi, K Engng Geol V31, N3/4, Dec 1991, P209-230
The space-time relation between epicentres of destructive large earthquakes (magnitude M (JMA) above 6.4) in the inner central belt of Japan has been analysed considering the block boundaries defined by Kanaori et al (1990). Space-time patterns are examined for each boundary and indicate periodic activity with the present time being an active period. Five regions having no earthquakes (seismic gaps) in the present active period are identified. Earthquakes of magnitude about 7 can be expected in the seismic gaps in the near future. Prediction of damaging earthquakes and seismic risk evaluation are discussed. 924020 Microearthquakes and seismotectonic analysis for a nuclear plant area in southeastern Finland Saari, J Engng Geol V31, N3/4, Dec 1991, P231-247
Seismicity of Precambrian Rapakivi Granite in an area of radius 100km around the Loviisa area has been studied. A local microearthquake monitoring network recorded 29 micro- and ultra-microearthquakes over a 6 year period. The events identify active faults in the area. Source parameters computed using a simple circular source model give peak slip less than 2.25mm, stress drops less than 0.2MPa, and source radii generally less than 50m. Earthquake depths were less than 5km. Peak slip values are discussed with reference to seismotectonic implications. 924021 Fractal features of the earthquake mechanism and a simple mechanical model Matsuzaki, M; Takayasu, H J Geophys Res V96, NB12, Nov 1991. P19925-19931
A simple model allowing easier understanding of the physical mechanisms of earthquakes than cellular automaton models is presented. The two dimensional stick-slip system displays dynamic order-disorder phase transition with a control parameter proportional to the strength of interaction. It can explain fractal features in seismicity, the locality of real earthquakes, and that local magnitude distributions deviate from the power law Gutenburg-Richter relation. 924022 Probabilistic assessment of earthquake hazard in Vietnam based on seismotectonic regionalization Phuong, N H Tectonophysies F198, NI, Nov 1991, P81-93
The theory of extreme values is applied to earthquake source zones in Vietnam using the first and third Gumbel distributions. The earthquake record from 1903-1988 is used. Mean return periods are calculated for earthquakes of different values together with probabilities of occurrence within a set period. The largest earthquake (Mmax = 7) is predicted for the Ma source zone within a return period of 123 years. A magnitude 6 event is predicted with 90% probability of occurrence for the north with 50 years, whilst for the south the magnitude and probability are 5 and 80% respectively.
© 1992 Pergamon Press Ltd. Reproduction not permitted