A moderate earthquake with moment magnitude Mw=5.5 (first shock) hit the
Subbibanique region in the East of Algeria at the locality of
Beni-Ilmène (NW of Msila) on 14 May, 2010 at 12h29mn (GMT). The
earthquake was located by the CRAAG at latitude 35.99° N and
longitude 4.19° E, the depth was 6 km. Three persons were killed,
hundred injured and huge damages were observed in the epicentral
... [Show full abstract] area
(Béni-Ilmène, Samma, Bendaoud, Ounougha). The Focal
Mechanism (FM) of the seismic source obtained by waveform modeling
(near-field) shows left-lateral strike-slip for the nodal plane oriented
N345° and right-lateral strike-slip for the second nodal plane
oriented N254°. A second shock stroke the region on 16 May 2010 at
06h52mn (GMT) with moment magnitude Mw=5.3. It is localized 9 km SW of
the first shock at latitude 35.96° N, longitude 4.06° E and 5 km
of depth. The FM obtained by waveform modeling shows reverse faulting
with nodal planes oriented NE-SW. A third shock hit the region on 23 may
2010 at 13h28 (GMT) with moment magnitude Mw=5.3, localized 7 km at the
south of the first shock at the latitude 35.93° N, longitude
4.12° N and 6 km of depth. The FM obtained shows a left-lateral
strike-slip plane oriented N355° and a right-lateral plane oriented
N85° similar to that of the first shock. Field investigations,
geologic and sismotectonic analysis lead us to conclude that the fault
plane of the first shock is oriented NNW-SSE, i.e corresponding to the
nodal plane [strike, Dip, Rake: 345°, 85°, 16°]. The second
and the third shocks were generated by separate faults [strike, Dip,
rake: 250°, 55°, 120°] and [Strike, Dip, rake: 355°,
90°,-12°] respectively. We show that the first shock raised the
Coulomb Stress Failure level on the fault planes that generated the two
following shocks of Mw 5.3.
