The repetition of large-earthquake ruptures
This survey of well-documented repeated fault rupture confirms that some faults have exhibited a "characteristic" behavior during repeated large earthquakes---that is, the magnitude, distribution, and style of slip on the fault has repeated during two or more consecutive events. In two cases faults exhibit slip functions that vary little from earthquake to earthquake. In one other well-documented case, however, fault lengths contrast markedly for two consecutive ruptures, but the amount of offset at individual sites was similar. Adjacent individual patches, 10 km or more in length, failed singly during one event and in tandem during the other. More complex cases of repetition may also represent the failure of several distinct patches. The faults of the 1992 Landers earthquake provide an instructive example of such complexity. Together, these examples suggest that large earthquakes commonly result from the failure of one or more patches, each characterized by a slip function that is roughly invariant through consecutive earthquake cycles. The persistence of these slip-patches through two or more large earthquakes indicates that some quasi-invariant physical property controls the pattern and magnitude of slip. These data seem incompatible with theoretical models that produce slip distributions that are highly variable in consecutive large events.
Additional Information© 1996 by the National Academy of Sciences. This paper was presented at a colloquium entitled "Earthquake Prediction: The Scientific Challenge," organized by Leon Knopoff (Chair), Keiiti Aki, Clarence R. Allen, James R. Rice, and Lynn R. Sykes, held February 10 and 11, 1995, at the National Academy of Sciences in Irvine, CA. Carrie Sieh assisted in drafting the figures. I deeply appreciate support during the past two decades by the National Earthquake Hazards Reduction Program, through the U.S. Geological Survey's external grants program. My studies of the Landers earthquake were supported by California Institute of Technology's Earthquake Research Affiliates and by the National Science Foundation/U.S. Geological Survey Southern California Earthquake Center. This paper is California Institute of Technology Division of Geological and Planetary Sciences contribution number 5588 and Southern California Earthquake Center contribution number 218. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Published - SIEpnas96.pdf