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The 2003 Boumerdes, Algeria earthquake: Regional moment tensor analysis
Author(s) -
Braunmiller Jochen,
Bernardi Fabrizio
Publication year - 2005
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 - 10.1029/2004gl022038
Subject(s) - geology , seismology , aftershock , hypocenter , seismogram , thrust fault , slip (aerodynamics) , seismic moment , geodesy , fault (geology) , earthquake rupture , focal mechanism , induced seismicity , physics , thermodynamics
We used regional broadband seismograms to determine seismic moment tensors for the destructive May 21, 2003 Boumerdes (Algeria) M w = 7.0 earthquake and its larger aftershocks. Fully automatic inversions using near‐real time data provided solutions for seven M w ≥ 4.7 events within 90 minutes after event occurrence. After adding off‐line data, we manually obtained 30 solutions (M w ≥ 3.8) from May 2003 to January 2004. All have shallow source depths (6–21 km). The median P‐axis orientation (338°) of 24 thrust and four strike‐slip events is consistent with Africa‐Eurasia plate motion (330°). The main shock hypocenter at 8–10 km depth at the coastline and its shallow southward dip (25° ± 5°) puts the fault surface trace 15–20 km offshore, consistent with documented seafloor deformation at the base of the continental slope. A main shock rupture length of about 50 km is deduced from first day aftershocks and location of strike‐slip events. The strike‐slip events probably define the western rupture end and indicate a left‐step of main convergence. Fault strike variability of thrust events suggests fault orientation changes and possibly fault segmentation.