Seismic-induced pore-water pressure records from the Mammoth Lakes, California, earthquake sequence of 25 to 27 May 1980

Abstract

Abstract Eight records of seismic-induced pore-water pressure and corresponding acceleration records were gathered from aftershocks of the 25 to 27 May 1980, Mammoth Lakes, California, earthquake sequence. The records were obtained from lakeshore sediments at Convict Lake that had undergone liquefaction and subsequent lateral-spreading failure. The pore-pressure records showed several similarities to corresponding strong-motion acceleration records. The pore-pressure traces show clear P- and S-wave phases and are in phase with corresponding P-wave components of the acceleration records. S-wave components of pore-pressure records appear most similar in waveform to one or the other of the corresponding horizontal acceleration components. Although the P-wave portions of pore pressure are in phase with their acceleration counterparts, the amplitudes are not related by a strictly proportional factor. S-wave portions of the porepressure records show a phase lag compared to the S wave of the respective acceleration trace. In most cases, the frequency of the pore-pressure S-wave components are also about 5 Hz lower in frequency than the acceleration S waves.