ISSN:
1420-9136
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract In this paper we evaluate the present state of the seismic regime in Southern California using the concentration parameter of seismogenic faults (K sf ,Sobolev andZavyalov, 1981). The purpose of this work is to identify potential sites for large earthquakes during the next five or ten years. The data for this study derived from the California Institute of Technology's catalog of southern California earthquakes, and spanned the period between 1932 to June 1982. We examined events as small asM L ≥1.8 but used a magnitude cutoff atM L =3.3 for a detailed analysis. The size of the target earthquakes (M M ) was chosen as 5.3 and 5.8. The algorithm for calculatingK sf used here was improved over the algorithm described bySobolev andZavyalov (1981) in that it considered the seismic history of each elementary seismoactive volume. The dimensions of the elementary seismoactive volumes were 50 km×50 km and 20 km deep. We found that the mean value ofK sf within 6 months prior to the target events was 6.1±2.0 for target events withM L ≥5.3 and 5.4≥1.8 for targets withM L ≥5.8. Seventy-three percent of the targets withM L ≥5.8 occurred in areas whereK sf was less than 6.1. The variance of the time between the appearance of areas with lowK sf values and the following main shocks was quite large (from a few months to ten years) so this parameter cannot be used here for accurate predictions of occurrence time. Regions where the value ofK sf was below 6.1 at the end of our data set (June, 1982) are proposed as the sites of target earthquakes during the next five to ten years. The most dangerous area is the area east of San Bernardino whereK sf values are presently between 2.9 and 3.7 and where there has been no earthquake withM L ≥5.3 since 1948.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00945164
