Global Prevalence of Double Benioff Zones
- From: "George" <george@xxxxxxxxxxxxxxx>
- Date: Tue, 31 Jul 2007 03:50:11 -0400
http://www.sciencemag.org/cgi/content/abstract/316/5830/1472
Michael R. Brudzinski,1* Clifford H. Thurber,2 Bradley R. Hacker,3 E.
Robert Engdahl4
Double Benioff zones provide opportunities for insight into seismogenesis
because the underlying mechanism must explain two layers of deep
earthquakes and the separation between them. We characterize layer
separation inside subducting plates with a coordinate rotation to calculate
the slab-normal distribution of earthquakes. Benchmark tests on
well-established examples confirm that layer separation is accurately
quantified with global seismicity catalogs alone. Global analysis reveals
double Benioff zones in 30 segments, including all 16 subduction zones
investigated, with varying subducting plate ages and stress orientations,
which implies that they are inherent in subducting plates. Layer separation
increases with age and is more consistent with dehydration of antigorite
than chlorite.
1 Geology Department, Miami University, Oxford, OH 45056, USA.
2 Department of Geology and Geophysics, University of Wisconsin, Madison,
WI 53706, USA.
3 Department of Earth Science, University of California, Santa Barbara, CA
93106, USA.
4 Department of Physics, University of Colorado, Boulder, CO 80309, USA.
* To whom correspondence should be addressed. E-mail: brudzimr@xxxxxxxxxx
.
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