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Fluid flow triggered migration of events in the 1989 Dobi Earthquake sequence of central Afar
Author(s) -
Noir J.,
Jacques E.,
Békri S.,
Adler P. M.,
Tapponnier P.,
King G. C. P.
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl02182
Subject(s) - geology , graben , seismology , crust , sequence (biology) , fluid pressure , anisotropy , geophysics , tectonics , mechanics , genetics , physics , quantum mechanics , biology
During the August 1989 sequence of earthquakes beneath the Dobi graben in Central Afar, principal events (including 10 shocks with M L ≥5.5) propagated ∼50 km north‐westwards in ∼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 ∼N115°E nearly parallel to the graben axis. With a value , it is about 10 times larger than the other two, consistent with fissure anisotropy in the graben. The order of magnitude of the permeability (∼10 −8 m²) 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.