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Learning to cope with faults
272A 935024 Study of site amplification effects on ground motions in Santiago, Chile Cruz, E; Riddell, R; Midorikawa, S Tectonophysics V218, N1/3, Feb 1993, P273-280 A comprehensive array of monitoring instruments was installed in the Santiago Valley in 1989, at seven field sites ranging from a reference rock outcrop to soft silty ground. Data from low intensity events occurring in 1989 and 1990 have been used in preliminary evaluation of site amplification effects. Mean amplification ratios have been computed for each site. Soil conditions are shown to influence amplification value,and this amplification varies depending on period range considered.
935025 Semi-empirical estimation of peak ground acceleration from large earthquakes Midorikawa, S Tectonophysics 1/218, NI/3, Feb 1993, P287-295 A method for synthesizing ground acceleration from a large earthquake is presented, based on the semi-empirical method of Irikura (1986) but simplified for engineering use. The fault is divided into small elements and acceleration envelope waveforms (instead of time histories) are determined using the empirical relations. These envelope waveforms are summed to produce that for the large earthquake. Peak acceleration is obtained from the maximum value of the summed envelope. Validation is demonstrated against data from the 1985 Central Chile earthquake.
935026 Seismotectonic models and physical parameters of faults in the United States Hays, W W Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Chevreuse, 22-23 October 1991 P53-67. Publ Nantes: Ouest Editions, 1991 Over 100 seismic source zones have been delineated in the USA. Each source requires characterisation by combined geologic, geophysical, seismological, and geodetic data. These zones represent regions characterised by low, moderate, and high seismicity, and subduction, normal, strike-slip, and thrust faulting. Earthquake hazard assessment is considered: the most critical parameters of a source and the seismic cycle, recurrence relations, fault segmentation, and maximum magnitude. Evaluation of these parameters is discussed.
935027 Space and time sealing laws for seismic source Bernard, P Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevreuse, 22-23 October 1991 P69-85. Publ Nantes: Ouest Editions, 1991 Seismic hazard assessment requires knowledge of potential seismic sources and their expected radiation. A short survey of the fundamental scaling laws relative to these is presented for an ideally simple seismic fault. Coseismic slip, seismic moment, and low and high frequency components of radiation
are discussed. Realistic accelerograms can be generated using spectral laws. Seismic hazard of a region can be calculated using the classical Gutenberg-Richter law.
935028 Learning to cope with faults Mallard, D J Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevrease, 22-23 October 1991 PIll-121. Publ Nantes: Ouest Editions, 1991 The timescale of the seismogenic process is far longer than the available historical record in areas of moderate seismicity. The uncertainties introduced by this lack of information can only be addressed using engineering judgement. The procedures developed by the nuclear industry in the UK to deal with faults are outlined. These involve decision whether it is necessary to take the fault into account; determination of the extent over which faults should be considered; recognising active faults and evaluating ground motion hazards; and assessing these hazards.
935029 Overview of the choice of seismic motion parameters for use in seismic design Menu, J M H Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevreuse, 22-23 October 1991 P165-186. Publ Nantes: Ouest Editions, 1991 Engineering parameters commonly used in seismic design are outlined, with particular reference to areas of moderate seismicity. In these areas, the frequency content distribution of response spectra, structural behaviour factors, and level of seismic aggression must be carefully considered. Because of the scarcity of seismic data, it has been necessary develop prediction techniques for seismic parameters. Effective Peak Acceleration should be defined for use as a fundamental parameter of seismic loading. Response spectra at a site are best estimated by a combined empirical-theoretical approach.
Frost action, permafrost and frozen ground 935O30 Hydraulic conductivity of compacted clay frozen and thawed in situ Benson, C H; Othman, M A J Geotech Engng Div ASCE V119, N2, Feb 1993, P276-294 A large specimen of compacted clay (diameter 298mm, height 914mm) was buried and subjected to freeze-thaw in the field for 60 days. Overall hydraulic conductivity remained essentially unchanged, but increases of 1.5-2 orders of magnitude were observed above the freezing front, highest at the top of the specimen and decreasing with depth. These increases were associated with cracks resulting from ice lens formation. Desiccation due to water redistribution also affected hydraulic conductivity below the freezing front. The general trend of conductivity changes can be predicted from tests on small specimens, but laboratory values were lower than those measured at field scale.
© 1993 Pergamon Press Ltd. Reproduction not permitted
935025 Semi-empirical estimation of peak ground acceleration from large earthquakes Midorikawa, S Tectonophysics 1/218, NI/3, Feb 1993, P287-295 A method for synthesizing ground acceleration from a large earthquake is presented, based on the semi-empirical method of Irikura (1986) but simplified for engineering use. The fault is divided into small elements and acceleration envelope waveforms (instead of time histories) are determined using the empirical relations. These envelope waveforms are summed to produce that for the large earthquake. Peak acceleration is obtained from the maximum value of the summed envelope. Validation is demonstrated against data from the 1985 Central Chile earthquake.
935026 Seismotectonic models and physical parameters of faults in the United States Hays, W W Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Chevreuse, 22-23 October 1991 P53-67. Publ Nantes: Ouest Editions, 1991 Over 100 seismic source zones have been delineated in the USA. Each source requires characterisation by combined geologic, geophysical, seismological, and geodetic data. These zones represent regions characterised by low, moderate, and high seismicity, and subduction, normal, strike-slip, and thrust faulting. Earthquake hazard assessment is considered: the most critical parameters of a source and the seismic cycle, recurrence relations, fault segmentation, and maximum magnitude. Evaluation of these parameters is discussed.
935027 Space and time sealing laws for seismic source Bernard, P Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevreuse, 22-23 October 1991 P69-85. Publ Nantes: Ouest Editions, 1991 Seismic hazard assessment requires knowledge of potential seismic sources and their expected radiation. A short survey of the fundamental scaling laws relative to these is presented for an ideally simple seismic fault. Coseismic slip, seismic moment, and low and high frequency components of radiation
are discussed. Realistic accelerograms can be generated using spectral laws. Seismic hazard of a region can be calculated using the classical Gutenberg-Richter law.
935028 Learning to cope with faults Mallard, D J Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevrease, 22-23 October 1991 PIll-121. Publ Nantes: Ouest Editions, 1991 The timescale of the seismogenic process is far longer than the available historical record in areas of moderate seismicity. The uncertainties introduced by this lack of information can only be addressed using engineering judgement. The procedures developed by the nuclear industry in the UK to deal with faults are outlined. These involve decision whether it is necessary to take the fault into account; determination of the extent over which faults should be considered; recognising active faults and evaluating ground motion hazards; and assessing these hazards.
935029 Overview of the choice of seismic motion parameters for use in seismic design Menu, J M H Proc International Conference on Seismic Hazard Determination in Areas with Moderate Seismicity, SaintRemy-Les-Cbevreuse, 22-23 October 1991 P165-186. Publ Nantes: Ouest Editions, 1991 Engineering parameters commonly used in seismic design are outlined, with particular reference to areas of moderate seismicity. In these areas, the frequency content distribution of response spectra, structural behaviour factors, and level of seismic aggression must be carefully considered. Because of the scarcity of seismic data, it has been necessary develop prediction techniques for seismic parameters. Effective Peak Acceleration should be defined for use as a fundamental parameter of seismic loading. Response spectra at a site are best estimated by a combined empirical-theoretical approach.
Frost action, permafrost and frozen ground 935O30 Hydraulic conductivity of compacted clay frozen and thawed in situ Benson, C H; Othman, M A J Geotech Engng Div ASCE V119, N2, Feb 1993, P276-294 A large specimen of compacted clay (diameter 298mm, height 914mm) was buried and subjected to freeze-thaw in the field for 60 days. Overall hydraulic conductivity remained essentially unchanged, but increases of 1.5-2 orders of magnitude were observed above the freezing front, highest at the top of the specimen and decreasing with depth. These increases were associated with cracks resulting from ice lens formation. Desiccation due to water redistribution also affected hydraulic conductivity below the freezing front. The general trend of conductivity changes can be predicted from tests on small specimens, but laboratory values were lower than those measured at field scale.
© 1993 Pergamon Press Ltd. Reproduction not permitted