Papers

Peer-reviewed
10 2017

Intermediate-depth earthquakes linked to localized heating in dunite and harzburgite

NATURE GEOSCIENCE
  • Tomohiro Ohuchi
  • ,
  • Xinglin Lei
  • ,
  • Hiroaki Ohfuji
  • ,
  • Yuji Higo
  • ,
  • Yoshinori Tange
  • ,
  • Takeshi Sakai
  • ,
  • Kiyoshi Fujino
  • ,
  • Tetsuo Irifune

Volume
10
Number
10
First page
771
Last page
+
Language
English
Publishing type
Research paper (scientific journal)
DOI
10.1038/NGEO3011
Publisher
NATURE PUBLISHING GROUP

The occurrence of intermediate-depth and deep earthquakes at depths greater than 60 km in subducting slabs has long puzzled geoscientists. These earthquakes require some mechanism to accelerate the fault movement at high pressures above 1.8 GPa. Localized heating would contribute to faulting, but experimental evidence for this mechanism has been limited to pressures of up to 0.5 GPa. Here we conduct deformation experiments on dry dunite samples at pressures of 1.0 to 2.6 GPa and temperatures of 860 to 1,350 K-conditions close to those for relatively shallow intermediate-depth earthquakes. We observe plastic deformation of the dunite, followed by faulting and acoustic emissions at an accelerated strain rate of about 5 x 10(-5) s(-1) or higher. We find that ultrafine-grained gouge layers containing iron-rich melt films, which is indicative of a very high peak temperature of about 2,110 K along the fault planes. We also observe faulting in wet harzburgite-a dehydration product of antigorite-at natural stress levels of 0.3 to 0.4 gigapascals. We therefore suggest that intermediate-depth earthquakes can be induced by localized heating both in dry and wet subducting slabs, if the background strain rate exceeds a threshold value in the range from 10(-16) to 10(-13) s(-1).

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Link information
DOI
https://doi.org/10.1038/NGEO3011
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000412102200015&DestApp=WOS_CPL