Fluid-controlled faulting process in the Asal Rift, Djibouti, from 8 yr of radar interferometry observations

被引:62
作者
Doubre, Cecile [1 ]
Peltzer, Gilles
机构
[1] Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA
[2] CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA
关键词
Afar; Asal Rift; faulting process; radar interferometry;
D O I
10.1130/G23022A.1
中图分类号
P5 [地质学];
学科分类号
0709 ; 081803 ;
摘要
The deformation in the Asal Rift (Djibouti) is characterized by magmatic inflation, diking, distributed extension, fissure opening, and normal faulting. An 8 yr time line of surface displacement maps covering the rift, constructed using radar interferometry data acquired by the Canadian satellite Radarsat between 1997 and 2005, reveals the aseismic behavior of faults and its relation with bursts of microseismicity. The observed ground movements show the asymmetric subsidence of the inner floor of the rift with respect to the bordering shoulders accommodated by slip on three of the main active faults. Fault slip occurs both as steady creep and during sudden slip events accompanied by an increase in the seismicity rate around the slipping fault and the Fieale volcanic center. Slip distribution along fault strike shows triangular sections, a pattern not explained by simple elastic dislocation theory. These observations suggest that the Asal Rift faults are in a critical failure state and respond instantly to small pressure changes in fluid-filled fractures connected to the faults, reducing the effective normal stress on their locked section at depth.
引用
收藏
页码:69 / 72
页数:4
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