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Diffraction of elastic waves by three-dimensional surface irregularities
221A The Coyote Lake, California, earthquake of magnitude 5.7 on the 6th August 1979 displaced a preexisting slump on the northeast shore of Lake Anderson and formed a fissure 20m long. Strong motion records, field measurements of the slope, estimates of the material properties and a dynamic numerical model based on the Newmark analysis of seismic slope stability enabled a predict~ displacement for the landslide to be calculated. The calculated displacement of 27ram agreed well with the actual displacement of 21ram.
846132 Specific barrier model for the quantitative description of inhomogeneons faulting and the prediction of strong ground motion. Part 2. Applications of the model Papageorgiou, A S; Aki, K Bull Seismoi Soc Am V73, N4, Aug 1983, P953-978 The specific barrier model is applied to a set of five strong Californian earthquakes: Kern County (1952), San Fernando (1971), Borrego Mountain (1968), Long Beach (1933) and Parkfield (1966). Source parameters such as barrier intervals, local stress drops, cohesive zone size and cohesive stress are inferred. It is concluded that the Fort Tejon (1857) and Kern County earthquakes are characterized by long barrier intervals and large slips while the Long Beach and Parkfield earthquakes are characterized by short barrier intervals and small slips. San Fernando and Borrego Mountain earthquakes lie between these two extremes. 49 refs.
846133 Study of the 20 January 1982 earthquake near Great Nicobar Island, India Agrawal, P N Bull Seismol Soc Am V73, N4. Aug 1983, P1139-1159 The shock effects of the earthquake are discussed including a large number of buildings that were damaged. An isoseismal map and microearthquake recording show that the activity migrated north-south. A number of building designs are recommended.
846134 Ground failure along the New River caused by the October 1979 Imperial Valley Earthquake sequence Heaton, T H; Anderson, J G; German, P T Bull Seismoi Soc Am V73. N4, Aug 1983, P1161-1171 A number of ground failures were noticed along the south bank of the New River, California, USA, following the 15 October 1979 Imperial Valley earthquake sequence. The ground failures formed a discontinuous zone 10km long and appeared to coincide with the aftershocks following the Brawley earthquake (the largest aftershock of the Imperial Valley earthquake). However, no cause and effect relationship could be demonstrated and no evidence of tectonic surface faulting was found.
846135 Possibility of induced seismicity in the vicinity of the Sleepy Hollow Oil Field, Southwestern Nebraska Rothe, G H; Lui, C Y Bull Seismol Soc Am V73, N5, Oct 1983, P1357-1367 An array of seismographs in the northwestern Kansas and southwestern Nebraska area detected 31 earthquakes over a period of one year. Sixteen of the earthquakes were in the immediate vicinity of the Sleepy Hollow Oil Field. It was concluded from investigations that water injection used at the oil field to enhance recovery was the probable cause of the earthquakes, although there was some evidence for a tectonic cause.
8461 Diffraction of elastic waves by three-dimensional surface irregularities Sanchez-Sesma, F J Bull Seismol Soc Am V73, N6, Dec 1983. P1621-1636 Topographical and geological irregularities can induce large amplifications and variations in ground motion during earthquakes. This paper uses a boundary method to study the scattering and diffraction of elastic waves by three-dimensional surface irregularities on the surface of a half-space. Some numerical results for vertical incidence of P waves are reported.
846137 Earthquake prediction: a new physical basis Crampin, S: Evans, R: Atkinson, B K Geophys J R Astr Soc V76, NI, Jan 1984, P147-156 (Paper to the Proceedings of the 1st International Workshop on Seismic Anisotropy, Suzdal, 11-19 May 1982) It is suggested that suberitical crack growth produces extensivedilatancy anisotropy (EDA) throughout earthquake zones. This process is a possible driving mechanism for earthquake precursors observed at substantial distances from impending focal zones and provides, in the shear wave splitting which has been observed in several seismic regions, a possible technique for monitoring the build-up of stress before earthquakes. 50 refs.
846138 Experimental study of the anisotropy of longitudinal and transverse waves from local earthquake records Bezgodkov, V A; Yegorkina, G V Geophys J R Astr Soe V76, N1, Jan 1984, P179-189 (Paper to the Proceedings of the 1st International Workshop on Seismic Anisotropy. Suzdal, 11-19 May 1982) The results of a study of the anisotropy of seismic wave velocities within the Ashkhabad test field in central Asia are presented. The anisotropy was studied by analysing variations in the values of apparent velocities of first arrivals for epicentral distances ranging from 30 to 130km and by analysing the delays between the arrival times of shear waves with different polarisations.
846139 Liquefaction-associated ground damage during the Vrancea earthquake of March 4, 1977 Ishihara, K; Perlea, V Soils Found V24, NI. March 1984, P90-112 The main damage due to the earthquake, other than landslides, was the widespread occurrence of liquefaction and sinkholes. Investigations into the liquefaction included borings and penetration tests. The results were used to analyse pore pressure build-up at 2 sites. Boring logs were used to investigate a huge sinkhole; results showed that a limestone layer existed 20m below the alluvial sand deposit and indicated that the sinkhole occurred as a result of ravelling failure in the karst of the limestone formation. An analysis indicated the cause of the sinkhole to be a seepage-associated instability due to an increase in pore water pressure.
846140 Structural analysis and interpretation of the surface deformalions of the El Asnam earthquake of October 10, 1980 Philip, H; Meghraoui, M Tectonics V2, NI, Feb 1983. P17-49 The tectonic analysis shows the principal mechanism consists of the activation of a NW-SE trending thrust fault, accompanied by left-lateral motion and intense deformation of the northwestern overthrusting block. 26 refs.
846132 Specific barrier model for the quantitative description of inhomogeneons faulting and the prediction of strong ground motion. Part 2. Applications of the model Papageorgiou, A S; Aki, K Bull Seismoi Soc Am V73, N4, Aug 1983, P953-978 The specific barrier model is applied to a set of five strong Californian earthquakes: Kern County (1952), San Fernando (1971), Borrego Mountain (1968), Long Beach (1933) and Parkfield (1966). Source parameters such as barrier intervals, local stress drops, cohesive zone size and cohesive stress are inferred. It is concluded that the Fort Tejon (1857) and Kern County earthquakes are characterized by long barrier intervals and large slips while the Long Beach and Parkfield earthquakes are characterized by short barrier intervals and small slips. San Fernando and Borrego Mountain earthquakes lie between these two extremes. 49 refs.
846133 Study of the 20 January 1982 earthquake near Great Nicobar Island, India Agrawal, P N Bull Seismol Soc Am V73, N4. Aug 1983, P1139-1159 The shock effects of the earthquake are discussed including a large number of buildings that were damaged. An isoseismal map and microearthquake recording show that the activity migrated north-south. A number of building designs are recommended.
846134 Ground failure along the New River caused by the October 1979 Imperial Valley Earthquake sequence Heaton, T H; Anderson, J G; German, P T Bull Seismoi Soc Am V73. N4, Aug 1983, P1161-1171 A number of ground failures were noticed along the south bank of the New River, California, USA, following the 15 October 1979 Imperial Valley earthquake sequence. The ground failures formed a discontinuous zone 10km long and appeared to coincide with the aftershocks following the Brawley earthquake (the largest aftershock of the Imperial Valley earthquake). However, no cause and effect relationship could be demonstrated and no evidence of tectonic surface faulting was found.
846135 Possibility of induced seismicity in the vicinity of the Sleepy Hollow Oil Field, Southwestern Nebraska Rothe, G H; Lui, C Y Bull Seismol Soc Am V73, N5, Oct 1983, P1357-1367 An array of seismographs in the northwestern Kansas and southwestern Nebraska area detected 31 earthquakes over a period of one year. Sixteen of the earthquakes were in the immediate vicinity of the Sleepy Hollow Oil Field. It was concluded from investigations that water injection used at the oil field to enhance recovery was the probable cause of the earthquakes, although there was some evidence for a tectonic cause.
8461 Diffraction of elastic waves by three-dimensional surface irregularities Sanchez-Sesma, F J Bull Seismol Soc Am V73, N6, Dec 1983. P1621-1636 Topographical and geological irregularities can induce large amplifications and variations in ground motion during earthquakes. This paper uses a boundary method to study the scattering and diffraction of elastic waves by three-dimensional surface irregularities on the surface of a half-space. Some numerical results for vertical incidence of P waves are reported.
846137 Earthquake prediction: a new physical basis Crampin, S: Evans, R: Atkinson, B K Geophys J R Astr Soc V76, NI, Jan 1984, P147-156 (Paper to the Proceedings of the 1st International Workshop on Seismic Anisotropy, Suzdal, 11-19 May 1982) It is suggested that suberitical crack growth produces extensivedilatancy anisotropy (EDA) throughout earthquake zones. This process is a possible driving mechanism for earthquake precursors observed at substantial distances from impending focal zones and provides, in the shear wave splitting which has been observed in several seismic regions, a possible technique for monitoring the build-up of stress before earthquakes. 50 refs.
846138 Experimental study of the anisotropy of longitudinal and transverse waves from local earthquake records Bezgodkov, V A; Yegorkina, G V Geophys J R Astr Soe V76, N1, Jan 1984, P179-189 (Paper to the Proceedings of the 1st International Workshop on Seismic Anisotropy. Suzdal, 11-19 May 1982) The results of a study of the anisotropy of seismic wave velocities within the Ashkhabad test field in central Asia are presented. The anisotropy was studied by analysing variations in the values of apparent velocities of first arrivals for epicentral distances ranging from 30 to 130km and by analysing the delays between the arrival times of shear waves with different polarisations.
846139 Liquefaction-associated ground damage during the Vrancea earthquake of March 4, 1977 Ishihara, K; Perlea, V Soils Found V24, NI. March 1984, P90-112 The main damage due to the earthquake, other than landslides, was the widespread occurrence of liquefaction and sinkholes. Investigations into the liquefaction included borings and penetration tests. The results were used to analyse pore pressure build-up at 2 sites. Boring logs were used to investigate a huge sinkhole; results showed that a limestone layer existed 20m below the alluvial sand deposit and indicated that the sinkhole occurred as a result of ravelling failure in the karst of the limestone formation. An analysis indicated the cause of the sinkhole to be a seepage-associated instability due to an increase in pore water pressure.
846140 Structural analysis and interpretation of the surface deformalions of the El Asnam earthquake of October 10, 1980 Philip, H; Meghraoui, M Tectonics V2, NI, Feb 1983. P17-49 The tectonic analysis shows the principal mechanism consists of the activation of a NW-SE trending thrust fault, accompanied by left-lateral motion and intense deformation of the northwestern overthrusting block. 26 refs.