Indication of high pore-fluid pressures in a seismically-active fault zone

被引:138
作者
Crampin, S
Volti, T
Chastin, S
Gudmundsson, A
Stefánsson, R
机构
[1] Univ Edinburgh, Dept Geol & Geophys, Grant Inst, Edinburgh EH9 3JW, Midlothian, Scotland
[2] British Geol Survey, Edinburgh Anisotropy Project, Edinburgh EH9 3LA, Midlothian, Scotland
[3] Japan Marine Sci & Technol Ctr, Yokohama, Kanagawa 2370061, Japan
[4] Univ Bergen, Inst Geol, N-5007 Bergen, Norway
[5] Iceland Meteorol Off, IS-150 Reykjavik, Iceland
关键词
90; degrees-flips; earthquakes; fault planes; high pressures; shear-wave splitting;
D O I
10.1046/j.1365-246X.2002.01830.x
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Polarisations of seismic shear-wave splitting observed above small earthquakes in Iceland are typically approximately NE to SW, parallel to the direction of maximum horizontal stress. In contrast, the polarisations of shear-waves at three new stations sited over the Husavik-Flatey Fault, a major seismically-active transform fault in northern Iceland, are approximately NW to SE, orthogonal to the stress-aligned polarisations elsewhere. Modelling suggests that these 90degrees-flips in polarisations are caused by propagation through cracks containing fluids at high pore-fluid pressures within one or two MPa of the critical stress. These observations suggest that high pore-fluid pressures, which play a key role in earthquake source mechanisms, can be monitored by analysing shear-wave splitting above seismically-active fault planes.
引用
收藏
页码:F1 / F5
页数:5
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