2006 Volume 2006 Issue 26 Pages 37-61
Large earthquakes frequently generate co-seismic surface ruptures. These provide much information about surface displacement which produced in a single event. Geomorphologic and geologic studies, such as field investigation and fault trace mapping, are made after earthquake aiming to describe various features of surface fault. Seismologic studies are also carried out in order to estimate source rupture processes for the subjacent source faults. To make an initial model of the subjacent source faults, many fault model parameters are derived from the features of surface faults, for example, location of the surface rupture, style of the faulting and displacements along the fault. It indicates that surface faults contain voluminous information, and their information is important to make practical subjacent source fault models.
We focus on the relationship between feature of surface faults and that of subjacent source faults, and make a research of examining the correlation among them. We start this study reviewing the feature of surface faults and fault model parameter and slip distribution of subjacent source faults as a basic data.
Our targets are the 1968 Meckering, the 1979 Imperial Valley, the 1983 Borah Peak, the 1987 Superstition Hills, the 1990 Luzon, the 1992 Landers, the 1995 Hyogo-ken Nanbu, the 1995 Neftegorsk, the 1999 Kocaeli, the 1999 Chi-Chi, the 1999 Hector Mine and the 1999 Di. izce earthquakes. In these earthquakes, both surface fault and subjacent source fault are well studied.
Compiling the information, we have made the catalog of surface faults and subjacent source faults. The items that contained in the catalog are location of the hypocenter; fault distribution; length; strike, dip and displacement of the surface faults; shape and slip distribution of the subjacent source faults, and so on. This catalog enables us to compare the features of these earthquakes on the unified point of view. Based on this catalog, we found following conclusions.1) Length of subjacent source faults are as long as length of surface faults, or longer than that of surface faults.2) Zones where surface displacements are large correspond to location of asperities on source faults in many cases.
