Streaks of microearthquakes along creeping faults

Abstract

Crustal faults that produce most of their slip aseismically typically generate large numbers of small earthquakes. These events have generally been interpreted as coming from localized patches of the fault that undergo unstable (stick±slip) sliding, surrounded by larger regions of stable sliding (creep). In published catalogues the microearthquakes often appear to be distributed over large portions of the fault surface. By accurately locating large numbers of microearthquakes from faults of different orientations in California and Hawaii, we show here that instead the locations de®ne highly concentrated streaks that are characteristically aligned in the direction of fault slip. The underlying cause of this structural organization of the fault surface remains to be determined.

Southern California Hypocenter Relocation with Waveform Cross-Correlation, Part 1: Results Using the Double-Difference Method

“…Several studies have identified streaks of microearthquakes along active fault surfaces in northern California (Rubin et al, 1999;Waldhauser et al, 1999;Rubin and Gillard, 2000;Waldhauser and Ellsworth, 2000). We do not observe comparable features in southern California, with the possible exception of seismicity streaks along the Imperial Fault (Shearer, 2002).…”

“…Waveform cross-correlation is an increasingly important tool for characterizing event similarity, improving earthquake locations, and studying source properties (Nakamura, 1978;Poupinet et al, 1984;Got et al, 1994;Dodge et al, 1995;Nadeau et al, 1995;Gillard et al, 1996;Rubin et al, 1999;Waldhauser et al, 1999). However, it is not yet used routinely for network data because of its greater computational requirements compared with standard processing based on phase picks.…”

Management of Post-mining Large-scale Ground Failures: Blast Swarms Field Experiment for Calibration of Permanent Microseismic Early-warning Systems

“…The recorded data might indeed be used to test the capabilities of "relative" location algorithms compared to "absolute" and classical seismic location algorithms. The relative approach is supposed to improve the location of one order of magnitude compared to absolute location (Rubin et al, 1999;Waldhauser and Ellsworth, 2000;Schaff et al, 2002).…”

Induced Microearthquake Patterns in Hydrocarbon and Geothermal Reservoirs: Six Case Studies

“…Automated methods must be investigated for this reason. Automated, cross correlation repicking methods have been successfully applied to natural earthquake data sets (Dodge et al, 1995;Shearer, 1997;Rubin et al, 1999), but have been less successful with induced data sets. Induced events from the same geometrical feature often produce waveforms that correlate poorly at one or more stations, even though waveforms at other stations might display high levels of similarity.…”