%0 Journal Article
%@ 0037-1106
%A Wyss, Max
%A Sammis, Charles
%A Nadeau, Robert
%A Wiemer, Stefan
%A World Agency of Planetary Monitoring and Earthquake Risk Reduction Route de Malagnou 36A CH-1208 Geneva, Switzerland,
%A (M.W.) University of Southern California Los Angeles, California 90007,
%A (C.G.S.) Berkeley Seismological Laboratory and Center for Computational Seismology Lawrence Berkeley National Laboratory University of California Berkeley, California 94720,
%A (R.M.N.) Institute of Geophysics ETH Hoenggerberg CH-8093, Zurich, Switzerland,
%D 2004
%F epos:1440
%I Seismological Society of America
%J Bulletin of the Seismological Society of America
%N 2
%P 410-421
%T Fractal Dimension and b-Value on Creeping and Locked Patches of the San Andreas Fault near Parkfield, California
%U https://episodesplatform.eu/eprints/1440/
%V 94
%X We tested the hypotheses (1) that the fractal dimension, D, of hypocenters are different in a locked and a creeping segment of the San Andreas fault and (2) that the relationship D~`2b holds approximately, where b is the slope of the frequency–magnitude relationship. The test area was the 30- to 50-km fault segment north of Parkfield for which two earthquake catalogs exist: the borehole High  Resolution Seismic Network data, and the U.S. Geological Survey data, which have a minimum magnitude of completeness of Mc 0.4 and Mc 1.0–1.2, respectively. The relative location errors in the two catalogs are estimated as 0.25 km and less than 1 km, respectively. The periods of high-quality data available extend from 1987 to  1998.5 and 1981 to 2000.2, respectively, furnishing 2609 and 3775 events for analysis, in the two catalogs. In the locked part, 0.5 < b < 0.7 and 0.96 < D < 1.14,  whereas in the creeping segment, 1.1 < b < 1.6 and 1.45 < D < 1.72. However, the spatial distribution of the hypocenters in the creeping segment is not well approximated by a fractal distribution. We conclude (1) that the frequency–magnitude distribution as described by b, as well as the fractal dimension (D), are different in  the locked and creeping segments near Parkfield; (2) that the spatial distribution in the creeping segment is not well approximated by a fractal distribution; and (3) that the relationship D~2b holds in the locked segment, where both parameters can be measured accurately. Thus, we propose that the heterogeneity of seismogenic  volumes lead to differences in D and b and that these differences, where established by high-quality data, may furnish clues concerning properties of fault zones.