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Theory of earthquake premonitory and fracture processes
244A
GEOLOGY:EARTHQUAKES
faults. The worldwide delimitation of these zones involves an enormous effort and is often rather subjective. Also, a complete recording of faults will not be available for a long time yet. The seismicity model presented in this paper therefore is not based on individually defined seismic zones but rather on the assumption that each point in a global 1/2° grid of coordinates represents a potential earthquake source. The earthquake occurrence frequency is determined purely statistically by appropriately spreading out the positions of past occurrences. All the other significant seismicity charaeteristies are determined in a global 1/2 ° grid of co-ordinates. This method of interpreting seismicity data allows us to establish a transparent, sufficiently precise representation of seismic hazard which is ideally suited for computer-aided risk analyses. (from Authors)
Warning of imminent ground shaking due to a large earthquake would be useful to a variety of agencies. This kind of ground-motion prediction is possible in southern California for events with magnitude less than 6, where path effects dominate. The 28 June 1991 Sierra Madre earthquake is presented as a test case for this concept. A single-station inversion of the record from the Pasadena station 20 km SW of the epicenter produces reasonable source parameters for the event. With these source parameters and a library of Green's functions calculated for an average southern California crustal model, ground motions can be predicted throughout the region. The development of a warning system can be approached in stages, starting with small events. With path effects determined by modeling moderate-size events, work can begin on developing distributed fault models to predict ground motions of great earthquakes. (from Authors)
966026
Scientific meeting on seismic protection. Proceedings of a
meeting, Venice, July 1993 ed V. Spagna & E. Schiavon, (Regione del Veneto, Dipartimento per la Geologia e le Attivita estrattive), 1995, 239 pp. The meeting was jointly sponsored by the Venetian Region, Department of Geology and Extractive Activities, and the National Survey for Seismic Protection of the Republic of Armenia. The papers concern earthquake activity mainly in Italy and Armenia, and are presented in four sections. Section I is subdivided into; Ia, organization of seismic protection and strategies for earthquake mitigation effects; and Ib, probabilistic seismic hazard analysis and regional seismogenetie models. Section II covers crustal movements, earthquake generating faults, focal mechanisms, seismic networks and geophysical earthquake precursors. Section III is entitled migration of fluids in the subsoil and geochemical precursor behaviour. Section IV deals with seismic precursor monitoring stations and laboratory and field instrumentation. (G.E.Hodgson) 966027
Theory of earthquake premonitory and fracture processes ed R. Teisseyre, (Polish Scientific Publishers, PWN, Warsaw), ISBN (hardback) 83 01 11771 0, price US$95.00, 1995, 648 pp, index. The collective monograph, prepared by the Japanese, Polish and US scientists, presents an attempt to describe the earthquake premonitory and fracturing processes in terms of physical models and theories. A continuum approach is mainly used, its most general form being related to the theory of continuum distribution of dislocations. However, the models related to discrete dislocations and to propagation of a single crack are also discussed, especially in relation to some earthquake premonitory phenomena. The book is divided into six parts as follows: deformation and fracturing of rocks; dislocations and cracks: earthquake and fault models; earthquake premonitory and rebound processes; differential geometry methods in deformation problems; thermal stresses and thermodynamics of earthquakes; and a micromorphie model of a seismic source zone. (after Publisher) 966028 Earthquake forecasting using subsatellite seismic information system A. Sh. Mekthiev, A. B. Gummatov & M. M. Seidov, Turkish Journal of Physics, 19(8), 1995, pp 982-986. Earthquake forecasting including site prediction, quake intensity and occurrence time and possible developments to these ends are reviewed. It is concluded that until now it is impossible to predict the time of occurrence reliably. (Authors) 966029 Preliminary work on an early warning and rapid response program for moderate earthquakes C. W. Scrivner & D. V. Helmberger, Bulletin - Seismological Society of America, 85(4), 1995, pp 1257-1265.
966030 Characteristics of surface waves generated by events on and near the Chinese nuclear test site A. L. Levshin & M. H. Ritzwoller, Geophysical Journal International, 123(1), 1995, pp 131-148. The paper characterizes surface waves at intermediate periods (5-30 s) generated by nuclear explosions and natural earthquakes occurring in and around the Chinese nuclear test site at Lop Nor, observed at epicentral distances between 10° and 20°. It presents observations of Rayleigh- and Love-wave group velocities, spectral amplitudes and polarizations for eight nuclear explosions and nine earthquakes recorded at IRIS and GEOSCOPE broad-band digital stations and at the Kirghiz Telemetered Seismic Network (KNET). The paper discusses the relevance of the differences in spectral amplitudes between earthquakes and explosions and of the appearance of higher modes on earthquake frequency-time diagrams to the problem of discriminating nuclear explosions from earthquakes. (from Authors) 966031 Mapping seismic hazard in the central and eastern United States A. Frankel, Seismological Research Letters, 66(4), 1995, pp 8-21. The US Geological Survey CLISGS) has been publishing probabilistic seismic hazard maps for the US since 1976. New national maps for the 1997 edition of the NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings, published by the Building Seismic Safety Council are being prepared. The USGS hazard maps are to be the basis for design value maps for buildings to be included in the Provisions. The paper is a progress report on the mapping effort for the central and eastern US, and describes the basic methodology for hazard mapping which uses four models to characterize hazard. These models are based on historical seismicity that has been spatiallysmoothed to different length scales. This differs from the traditional approach where area source zones are drawn around seismicity or tectonic provinces for the calculation of seismic hazard. (from Author) 966032 Source parameters and crustal Q for four earthquakes in South Carolina J. B. Fletcher, Seismological Research Letters, 66(4), 1995, pp 44-58. Two three-component seismometers (one surface and one borehole) were re-installed on the Savannah River Site (SRS), South Carolina in July 1992 to determine attenuation in the Coastal Plain sediment wedge and source parameters of local earthquakes. Four earthquakes M ,-d.8 to 3.6 were recorded during the next 6 months. The largest event was located near Summerville within the meizoseismal area for the 1886 Charleston earthquake. Although source parameters have been determined from strong motion data and short-period regional networks for east coast earthquakes, these are some of the first source parameters determined from broad-band digital recorders. The paper determines source parameters
GEOLOGY:EARTHQUAKES
faults. The worldwide delimitation of these zones involves an enormous effort and is often rather subjective. Also, a complete recording of faults will not be available for a long time yet. The seismicity model presented in this paper therefore is not based on individually defined seismic zones but rather on the assumption that each point in a global 1/2° grid of coordinates represents a potential earthquake source. The earthquake occurrence frequency is determined purely statistically by appropriately spreading out the positions of past occurrences. All the other significant seismicity charaeteristies are determined in a global 1/2 ° grid of co-ordinates. This method of interpreting seismicity data allows us to establish a transparent, sufficiently precise representation of seismic hazard which is ideally suited for computer-aided risk analyses. (from Authors)
Warning of imminent ground shaking due to a large earthquake would be useful to a variety of agencies. This kind of ground-motion prediction is possible in southern California for events with magnitude less than 6, where path effects dominate. The 28 June 1991 Sierra Madre earthquake is presented as a test case for this concept. A single-station inversion of the record from the Pasadena station 20 km SW of the epicenter produces reasonable source parameters for the event. With these source parameters and a library of Green's functions calculated for an average southern California crustal model, ground motions can be predicted throughout the region. The development of a warning system can be approached in stages, starting with small events. With path effects determined by modeling moderate-size events, work can begin on developing distributed fault models to predict ground motions of great earthquakes. (from Authors)
966026
Scientific meeting on seismic protection. Proceedings of a
meeting, Venice, July 1993 ed V. Spagna & E. Schiavon, (Regione del Veneto, Dipartimento per la Geologia e le Attivita estrattive), 1995, 239 pp. The meeting was jointly sponsored by the Venetian Region, Department of Geology and Extractive Activities, and the National Survey for Seismic Protection of the Republic of Armenia. The papers concern earthquake activity mainly in Italy and Armenia, and are presented in four sections. Section I is subdivided into; Ia, organization of seismic protection and strategies for earthquake mitigation effects; and Ib, probabilistic seismic hazard analysis and regional seismogenetie models. Section II covers crustal movements, earthquake generating faults, focal mechanisms, seismic networks and geophysical earthquake precursors. Section III is entitled migration of fluids in the subsoil and geochemical precursor behaviour. Section IV deals with seismic precursor monitoring stations and laboratory and field instrumentation. (G.E.Hodgson) 966027
Theory of earthquake premonitory and fracture processes ed R. Teisseyre, (Polish Scientific Publishers, PWN, Warsaw), ISBN (hardback) 83 01 11771 0, price US$95.00, 1995, 648 pp, index. The collective monograph, prepared by the Japanese, Polish and US scientists, presents an attempt to describe the earthquake premonitory and fracturing processes in terms of physical models and theories. A continuum approach is mainly used, its most general form being related to the theory of continuum distribution of dislocations. However, the models related to discrete dislocations and to propagation of a single crack are also discussed, especially in relation to some earthquake premonitory phenomena. The book is divided into six parts as follows: deformation and fracturing of rocks; dislocations and cracks: earthquake and fault models; earthquake premonitory and rebound processes; differential geometry methods in deformation problems; thermal stresses and thermodynamics of earthquakes; and a micromorphie model of a seismic source zone. (after Publisher) 966028 Earthquake forecasting using subsatellite seismic information system A. Sh. Mekthiev, A. B. Gummatov & M. M. Seidov, Turkish Journal of Physics, 19(8), 1995, pp 982-986. Earthquake forecasting including site prediction, quake intensity and occurrence time and possible developments to these ends are reviewed. It is concluded that until now it is impossible to predict the time of occurrence reliably. (Authors) 966029 Preliminary work on an early warning and rapid response program for moderate earthquakes C. W. Scrivner & D. V. Helmberger, Bulletin - Seismological Society of America, 85(4), 1995, pp 1257-1265.
966030 Characteristics of surface waves generated by events on and near the Chinese nuclear test site A. L. Levshin & M. H. Ritzwoller, Geophysical Journal International, 123(1), 1995, pp 131-148. The paper characterizes surface waves at intermediate periods (5-30 s) generated by nuclear explosions and natural earthquakes occurring in and around the Chinese nuclear test site at Lop Nor, observed at epicentral distances between 10° and 20°. It presents observations of Rayleigh- and Love-wave group velocities, spectral amplitudes and polarizations for eight nuclear explosions and nine earthquakes recorded at IRIS and GEOSCOPE broad-band digital stations and at the Kirghiz Telemetered Seismic Network (KNET). The paper discusses the relevance of the differences in spectral amplitudes between earthquakes and explosions and of the appearance of higher modes on earthquake frequency-time diagrams to the problem of discriminating nuclear explosions from earthquakes. (from Authors) 966031 Mapping seismic hazard in the central and eastern United States A. Frankel, Seismological Research Letters, 66(4), 1995, pp 8-21. The US Geological Survey CLISGS) has been publishing probabilistic seismic hazard maps for the US since 1976. New national maps for the 1997 edition of the NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings, published by the Building Seismic Safety Council are being prepared. The USGS hazard maps are to be the basis for design value maps for buildings to be included in the Provisions. The paper is a progress report on the mapping effort for the central and eastern US, and describes the basic methodology for hazard mapping which uses four models to characterize hazard. These models are based on historical seismicity that has been spatiallysmoothed to different length scales. This differs from the traditional approach where area source zones are drawn around seismicity or tectonic provinces for the calculation of seismic hazard. (from Author) 966032 Source parameters and crustal Q for four earthquakes in South Carolina J. B. Fletcher, Seismological Research Letters, 66(4), 1995, pp 44-58. Two three-component seismometers (one surface and one borehole) were re-installed on the Savannah River Site (SRS), South Carolina in July 1992 to determine attenuation in the Coastal Plain sediment wedge and source parameters of local earthquakes. Four earthquakes M ,-d.8 to 3.6 were recorded during the next 6 months. The largest event was located near Summerville within the meizoseismal area for the 1886 Charleston earthquake. Although source parameters have been determined from strong motion data and short-period regional networks for east coast earthquakes, these are some of the first source parameters determined from broad-band digital recorders. The paper determines source parameters