Rupture length of the October 9, 1995 Colima-Jalisco earthquake (Mw 8) estimated from tsunami data

Abstract

We analyze tsunami data of the great 1995 Colima-Jalisco, Mexico earthquake, recorded in Cabo San Lucas, Baja California Sur, to estimate its rupture length, L. To model the tsunami arrival time, we assume a rectangular source area, oriented parallel to the trench, whose SE limit is fixed at the point of rupture initiation. The NW limit of the source area, i.e., L, is varied between 120 and 200 km. The comparison between synthetic and observed data strongly suggests that L of the earthquake was 160±20 km. This length agrees with those reported in various other studies of the earthquake. It, however, disagrees with a previous study, based on the same tsunami data, which suggested that the rupture may have extended 250 km NW from the epicenter [Tanioka and Ruff, 1996]. The cause of this discrepancy is most likely an error in the timing of the records used by Tanioka and Ruff [1996]. We conclude that the earthquake only partially ruptured the Rivera-North America plate interface. A 120 km-long segment in the NW extreme of this interface, which apparently ruptured in 1932, remains presently unbroken. Copyright 1998 by the American Geophysical Union.