Depth variation of coseismic stress drop explains bimodal earthquake magnitude-frequency distribution

O. Zielke, Ramon Arrowsmith

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19 Scopus citations

Abstract

[1] An essential part of seismic hazard analysis is the earthquake size-frequency relationship, used to estimate earthquake recurrence time, and thus probability. A key feature of those distributions is their bimodal character: small to moderate magnitude earthquakes follow the Gutenberg-Richter (GR) inverse power-law relation while large magnitude (characteristic) earthquakes are more frequent than anticipated from GR, following approximately a gaussian distribution around the maximum magnitude limited by fault geometry. Using a numerical earthquake simulator, we show that the temperature dependence of friction behavior and therefore the depth-variation of coseismic stress drop, derived from laboratory friction experiments, presents a simple and comprehensive explanation for the observed bimodal seismicity distribution. Characteristic earthquakes are the result of an abrupt increase in rupture width at the transition from small to large earthquakes.

Original languageEnglish (US)
Article numberL24301
JournalGeophysical Research Letters
Volume35
Issue number24
DOIs
StatePublished - Dec 28 2008

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ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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