A fault model of the 1995 Kobe earthquake derived from the GPS data on the Akashi Kaikyo Bridge and other datasets

Abstract

Co-seismic horizontal displacements, which have been obtained from recently released GPS observations on the Akashi Kaikyo Bridge, are examined for their consistency with displacements observed in the vicinity of the bridge. An E18.7°S displacement of 25.0 cm should be removed from them. The adjusted data indicate an additional fault segment beneath Akashi Strait. We construct a new fault model by adding this segment to a model assumed previously. We then recover the slip distribution over the new model by inverting these data together with other geodetic observations. The displacements calculated from the recovered distribution fit the observations well, and the distribution of slip indicates that the additional segment is closely related to the southern main segment of the previous model. Joint inversion of the geodetic and waveform datasets suggests large slips with longer duration in the shallow parts of these segments.