Full Aftershock Sequence of the M w 6.9 2003 Boumerdes Earthquake, Algeria: Space–Time Distribution, Local Tomography and Seismotectonic Implications

Sub-vertical low-velocity zone from P and S wave local tomography of the aftershock sequence of the Mw5.9 Chenoua (Algeria) earthquake of October 29, 1989: relict of the Miocene Eurasia–Africa suture zone?

“…The more recent tomographic inversion (Kherroubi et al 2017) based on the LOTOS program and a denser database confirmed previous results.…”

Tectonic Inversion and Geomorphic Evolution of the Algerian Margin Since Messinian Times: Insights From New Onshore/Offshore Analog Modeling Experiments

“…Our wedge model is based on the assumption of the occurrence of a décollement layer located beneath the margin and dipping below the margin. Although such a structure has been only indirectly suggested as crustal flat‐ramp systems by seismic studies (Aïdi et al., 2018; Déverchère et al., 2005; Roure et al., 2012), the existence of a crustal decoupling layer in the lower crust of the stretched continental margin is supported by the M w 6.9 2003 Boumerdès‐Zemmouri earthquake source location and aftershock sequence (Kherroubi et al., 2017). Many fold‐and‐thrust belts worldwide depict a similar style of thick‐skinned tectonics (Pfiffner, 2017).…”

“… (a) Synthetic cross‐section of the Algerian margin at the longitude of Greater Kabylia (see Figure 3 for location) realized after (b) line drawing of Maradja seismic line offshore (Strzerzynski et al., 2010), (c) geologic cross‐section on land (Raymond, 1976), and (d) a velocity cross‐section based on wide‐angle seismic data (Aïdi et al., 2018), with the approximate position of the 2003 Boumerdès‐ Zemmouri hypocenter and focal solution after Kherroubi et al. (2017). …”

“…The M w 6.9 May 21, 2003 Boumerdès‐Zemmouri event has evidenced a ∼55 km long active reverse fault (strike N70°, dip 40°S, rake 95°, depth range 2–11 km; Delouis et al., 2004) striking parallel to the coastline (Bounif et al., 2004; Kherroubi et al., 2017). Aftershocks, local tomography, and geodetic measurements show that the earthquake occurred on a south‐dipping thrust located at 6–10 km depth below the shoreline with ramp–flat–ramp systems upward and strong afterslip toward the surface, near the margin toe (Kherroubi et al., 2017; Mahsas et al., 2008) (Figures 1 and 4).…”

“…The M w 6.9 May 21, 2003 Boumerdès‐Zemmouri event has evidenced a ∼55 km long active reverse fault (strike N70°, dip 40°S, rake 95°, depth range 2–11 km; Delouis et al., 2004) striking parallel to the coastline (Bounif et al., 2004; Kherroubi et al., 2017). Aftershocks, local tomography, and geodetic measurements show that the earthquake occurred on a south‐dipping thrust located at 6–10 km depth below the shoreline with ramp–flat–ramp systems upward and strong afterslip toward the surface, near the margin toe (Kherroubi et al., 2017; Mahsas et al., 2008) (Figures 1 and 4). From recent wide‐angle seismic data, the Moho is found at 20–25 km depth beneath the continental domain, evidencing a relatively thin continental crust over ∼60 km across strike, while toward the Algerian basin, the Moho rises to a depth of about 10 km and the crust is of oceanic type (Aïdi et al., 2018; Bouyahiaoui et al., 2015; A. Leprêtre et al., 2013).…”