open access

https://hdl.handle.net/2115/66866

Opal-CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones

英語

asperity

2017-01-28

American Geophysical Union

Geophysical research letters

44(2)

687-693

Thick accumulation of chert is a ubiquitous feature of old oceanic plates at convergent margins. In this study, we investigate chert fragments recovered by the Integrated Ocean Drilling Program expedition 343 at the Japan Trench where the 2011 Tohoku-Oki earthquake (M-w 9.0) occurred. This sample provides a unique opportunity to investigate in situ chert diagenesis at an active subduction margin and its influence on the kinematics of megathrust faulting. Our mineralogical analyses revealed that the chert is characterized by hydrous opal-CT and may therefore be highly deformable via pressure solution creep and readily accommodate shear strain between the converging plates at driving stresses of kilopascal order. As chert diagenesis advances, any further deformation requires stresses of >100MPa, given the increasing transport distances for solutes as represented in cherts on land. The chert diagenesis is thus related to the mechanical transition from a weakly to strongly coupled plate interface at this margin.

学術雑誌論文

Version of Record

An edited version of this paper was published by AGU. Copyright 2017 American Geophysical Union. Kameda, J., A. Okamoto, K. Sato, K. Fujimoto, A. Yamaguchi, and G. Kimura (2017), Opal-CT in chert beneath the toe of the Tohoku margin and its influence on the seismic aseismic transition in subduction zones, Geophys. Res. Lett., 44, 687–693, doi:10.1002/2016GL071784. To view the published open abstract, go to http://dx.doi.org and enter the DOI.

0094-8276