|Title||Fluid flow triggered migration of events in the 1989 Dobi earthquake sequence of Central Afar|
|Publication Type||Journal Article|
|Year of Publication||1997|
|Authors||Noir J, Jacques E, Bekri S, Adler PM, Tapponnier P, King GCP|
|Journal||Geophysical Research LettersGeophysical Research Letters|
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.