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AGU: Journal of Geophysical Research, Solid Earth

 

Keywords

  • non-volcanic tremor
  • Mw 9.2 2004 Sumatra earthquake
  • San Andreas Fault near Parkfield

Index Terms

  • Seismology: Seismicity and tectonics
  • Seismology: Transform faults
  • Structural Geology: Role of fluids
  • Tectonophysics: Stresses: crust and lithosphere
Abstract
Cited By (4)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, B00A15, 12 PP., 2009
doi:10.1029/2008JB006062

Complex nonvolcanic tremor near Parkfield, California, triggered by the great 2004 Sumatra earthquake

Abhijit Ghosh

Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

John E. Vidale

Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

Zhigang Peng

School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

Kenneth C. Creager

Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

Heidi Houston

Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

In several instances, the passing surface waves from large earthquakes have ignited nonvolcanic tremor (NVT) on major faults. Still, the mechanism of tremor and its reaction to the dynamic stressing from various body and surface waves is poorly understood. We examine tremor near Parkfield, California, beneath the San Andreas fault triggered by the Mw 9.2, 2004 Sumatra earthquake. The prolonged shaking produces the richest and the most varied observations of dynamically triggered tremor to date. The tremor appears in at least three distinct locations and shows activity pulsing with encouraging stress, as has been observed in other cases. The greatest amount of triggering and tremor modulation accompanies the long-period Love waves. Rayleigh waves, on the other hand, appear to be less effective in exciting tremor sources. Also, at times, the tremor stops before the surface waves are complete, at other times it continues quivering after the waves have passed. While tremor is found to be sensitive to small stress changes, there are times when stresses of comparable magnitudes do not trigger noticeable tremor. Some tremors in this NVT sequence appear to be associated with the passage of P waves, which is unusual and surprising given the small stresses they impart.

Received 1 September 2008; accepted 21 August 2009; published 4 December 2009.

Citation: Ghosh, A., J. E. Vidale, Z. Peng, K. C. Creager, and H. Houston (2009), Complex nonvolcanic tremor near Parkfield, California, triggered by the great 2004 Sumatra earthquake, J. Geophys. Res., 114, B00A15, doi:10.1029/2008JB006062.

Cited By

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