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Seismic triggering by rectified diffusion in geothermal systems

Sturtevant, Bradford and Kanamori, Hiroo and Brodsky, Emily E. (1996) Seismic triggering by rectified diffusion in geothermal systems. Journal of Geophysical Research B, 101 (B11). pp. 25269-25282. ISSN 0148-0227. doi:10.1029/96JB02654.

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Widespread seismicity was triggered by the June 28, 1992, Landers California, earthquake at a rate which was maximum immediately after passage of the exciting seismic waves. Rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake. In a hydrothermal system modeled as a two-component H_2O-CO_2 fluid in porous rock the pressure initially increases linearly with time. The rate of pressure buildup depends sensitively on the mean bubble radius and is large for small bubbles. The diffusion-induced pressure is relaxed by percolation and resorption of vapor into the liquid solution. The induced seismicity itself also relieves stress. Values of parameters used in the present calculations give results consistent with observations of triggered seismicity at Long Valley caldera after the Landers earthquake. For one representative condition, at 250°C and 5.6 km depth, oscillating strain acting on 10-μm-diameter bubbles increases pore pressure at the rate of 151 Pa/s resulting in a pressure increase of 12 kPa in the 80-s duration of the Landers earthquake. The elevated pressure induced by a single 26-m-diameter cloud of bubbles in saturated rock relaxes by percolation through soil of 0.2-mdarcy permeability in 53.6 hours. Observations of earthquake swarms at other locations suggest that self-induced buildup of pore pressure by rectified diffusion can provide a positive feedback mechanism for amplifying seismicity.

Item Type:Article
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URLURL TypeDescription
Kanamori, Hiroo0000-0001-8219-9428
Brodsky, Emily E.0000-0002-6855-6860
Additional Information:Copyright 1996 by the American Geophysical Union. (Received March 5, 1996; revised August 26, 1996; accepted August 29, 1996.) Paper number 96JB02654. The authors thank Egill Hauksson for providing accelerograms of the Landers earthquake recorded in Long Valley and D. P. Hill for a useful review of an early version of this paper. Reviews by A. T. Linde and an anonymous reviewer helped clarify many important points. This paper is based upon work supported under a National Science Foundation Graduate Fellowship and it is contribution 5662 of the Division of Geological and Planetary Sciences, California Institute of Technology.
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NSF Graduate Research FellowshipUNSPECIFIED
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Caltech Division of Geological and Planetary Sciences5662
Issue or Number:B11
Record Number:CaltechAUTHORS:20141030-084918897
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Official Citation:Sturtevant, B., H. Kanamori, and E. E. Brodsky (1996), Seismic triggering by rectified diffusion in geothermal systems, J. Geophys. Res., 101(B11), 25269–25282, doi:10.1029/96JB02654.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51044
Deposited By: George Porter
Deposited On:30 Oct 2014 16:48
Last Modified:10 Nov 2021 19:04

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