open access

https://hdl.handle.net/2115/20437

Slow postseismic recovery of geoid depression formed by the 2004 Sumatra-Andaman Earthquake by mantle water diffusion

英語

Sumatra earthquake

2007-03-31

American Geophysical Union

Geophysical Research Letters

34(6)

L06313

Earthquakes are accompanied with mass redistributions and cause changes in gravity field and shape of geoid, an equipotential surface coincident with the mean sea surface. Such coseismic changes were detected by satellite gravimetry after the 2004 Sumatra-Andaman Earthquake [Han et al., 2006], but little has been known on what happens on geoid after the earthquake. Here we report slow postseismic recovery of coseismic geoid depression from satellite measurements. This cannot be explained with simple afterslip or viscous relaxation of Maxwellian upper mantle. It suggests the relaxation of coseismic dilatation and compression by the diffusion of supercritical H2O abundant in the upper mantle. Such a self-healing system of coseismic geoid undulations, a brand-new role of water in mantle, would significantly reduce the amount of permanent shifts of the Earth’s rotation axis by earthquakes.

学術雑誌論文

Accepted Manuscript

An edited version of this paper was published by AGU. Copyright 2007 American Geophysical Union.

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