Coastal uplift and thrust faulting associated with the M_w = 6.8 Zemmouri (Algeria) earthquake of 21 May, 2003

Abstract

[1] A shoreline uplift marked by a continuous white band visible at rocky headlands occurred during the 21 May 2003 earthquake (Mw 6.8) in northern Algeria. We measured the amount of coastal uplift on a white band (emerged algae) and harbors quays between Boumerdes and Dellys. Most of measured points were collected using tape and differential GPS on rocky headlands with s ± 0.15 m error bar (tidal prism). Leveling lines running parallel and orthogonal to the coast also provide the precise amount of uplift in the epicentral area. The uplift distribution shows an average 0.55 m along the shoreline with a maximum 0.75 m east of Boumerdes and a minimum close to 0 near Cap Djinet. The active deformation related to a thrust fault is modeled along the $55 km coastline. The dislocation model predicts surface slip on a N 54°E trending reverse fault, dipping 50°S E in agreement with CMT solution and coastal uplift. The faulting characteristics imply a fault geometry with possible sea bottom ruptures between 5 to 10 km offshore.

Searching for the seafloor signature of the 21 May 2003 Boumerdès earthquake offshore central Algeria

“…Although a paleoseismological approach based on a single core is not possible, the position of this core less than 5 km away from the cable breaks suggests that the sampled turbidites may be seismically triggered. It is also worth to note the following: (1) the mean recurrence interval of turbidites in core PSM-KS23 is of the same order as the mean 720-yr interval proposed by Meghraoui et al (1988) from their paleoseismic investigation led on the El Asnam fault onshore, ∼250 km W-SW from the Boumerdès earthquake area, and (2) large events in the eastern Algiers area are very rare over the last 1200 yr according to historical records (Hamdache et al, 2010), supporting a possible causative link between a given earthquake shaking threshold and multi-source turbidity currents triggered at this place.…”

Liquefaction hazard mapping in the city of Boumerdès, Northern Algeria

“…As a consequence of this geodynamic process a series of active faults trending NE-SW affects the Tell Atlas chain (Meghraoui et al 1988;Meghraoui 1991;Aoudia and Meghraoui 1995;Bouhadad 2001;Meghraoui et al 2004;, Bouhadad 2013Maouche et al 2013). These multi-segment faults were responsible for several strong earthquakes in the past (Philip and Meghraoui 1983;Meghraoui et al 2004) and are likely to produce strong seismic events in the future (Bouhadad and Laouami 2002). Several historical strong earthquakes have been mentioned in the available seismicity catalogs of Algeria (Benouar 1994;CRAAG 1994;Ayadi et Bezzeghoud, 2015).…”

“…Several historical strong earthquakes have been mentioned in the available seismicity catalogs of Algeria (Benouar 1994;CRAAG 1994;Ayadi et Bezzeghoud, 2015). The city of Boumerdès considered, before the May 21, 2003 (Mw = 6.8) earthquake, as a seismically quite and safe area, has to consider now the impact of major active faults recently revealed and/or identified both offshore and onshore Meghraoui et al 2004;Deverchère et al 2005;Benfedda et al 2017). Indeed, the Zemmouri 2003 earthquake revealed a 50 km long active reverse fault, located offshore, oriented NE-SW and dipping 50°to the SW (Bounif et al 2004;Meghraoui et al 2004;Belabbes et al 2009).…”

“…The city of Boumerdès considered, before the May 21, 2003 (Mw = 6.8) earthquake, as a seismically quite and safe area, has to consider now the impact of major active faults recently revealed and/or identified both offshore and onshore Meghraoui et al 2004;Deverchère et al 2005;Benfedda et al 2017). Indeed, the Zemmouri 2003 earthquake revealed a 50 km long active reverse fault, located offshore, oriented NE-SW and dipping 50°to the SW (Bounif et al 2004;Meghraoui et al 2004;Belabbes et al 2009). After this seismic event Boumerdès city is now reclassified in zone III, corresponding to the highest hazard zone in the new Algerian seismic code classification (RPA 2003).…”

Simulation systems for tsunami wave propagation forecasting within the French tsunami warning center

“…The coseismic deformation of the 2003 Boumerdès earthquake has been widely studied (e.g., Semmane et al, 2005;Meghraoui et al, 2004;Yelles et al, 2004), being among the largest events to occur in the western Mediterranean over the past 25 yr. For the comparison, we choose to use the source parameters proposed by Yelles et al (2004), whose characteristics are a reverse rectangular fault plane of 32 km length by 14 km width. The azimuth, dip, rake and slip values are N60 • , 42 • S, 84 • and 1.8 m, respectively.…”