Fluid flow triggered migration of events in the 1989 Dobi earthquake sequence of Central Afar

被引:128
作者
Noir, J
Jacques, E
Bekri, S
Adler, PM
Tapponnier, P
King, GCP
机构
[1] Inst. de Physique du Globe de Paris, 75252 Paris Cedex 05
关键词
D O I
10.1029/97GL02182
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
During the August 1989 sequence of earthquakes beneath the Dobi graben in Central Afar, principal events (including 10 shocks with M-L greater than or equal to 5.5) propagated similar to 50 km north-westwards in similar to 50 h. The sequence is analyzed in terms of triggering by propagation of a critical pore pressure wave in a compressible fluid through a fractured medium. The macroscopic fluid diffusion tensor D in the crust beneath the graben is estimated. Its principal eigenvector strikes similar to N115 degrees E nearly parallel to the graben axis. With a value (D) over bar xx similar to 2 km(2)/min, it is about 10 times larger than the other two, consistent with fissure anisotropy in the graben. The order of magnitude of the permeability (similar to 10(-8) m(2)) is compatible with characteristic fissure widths ranging from 1 mm to 3 cm. Estimating such parameters in other extensional regions might help to understand better the temporal evolution of seismic swarms.
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页码:2335 / 2338
页数:4
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