The large Algerian earthquakes (267 A.D.-2017)

Abstract

In northern Algeria, large earthquakes occurred in the past as the El Asnam earthquake of October 10th, 1980 (Ms:7.3), one of the strongest event ever recorded in the western Mediterranean region. There were located mostly in the Tellian Atlas, some of them off the coastline as the Algiers (1365), Oran (1790), Djidjelli (1856) earthquakes or the last Boumerdes earthquake (2003). On land, no strong earthquakes have been recorded in the High plateaus or along the Saharan Atlas. From a synthesis of seismological or geodynamical studies carried out on the Algerian seismicity, we conclude that these main events along the African-Eurasiatic plate boundary are representative of the actual deformation pattern of the different geological domains of northern Algeria. They are generated mainly by reverse faults or strike slip faults in relation with the NW-SE to NNW-SSE stress regime (σ 1 striking N330°- N350°) inherited from the oblique convergence process between the two main plates in the western Mediterranean region. They are in general superficial located in the upper part of the crust (no more than 20 Km). Important earthquakes do not occur very often in Algeria in comparison with other seismic regions of the world. Their return period are estimated in some regions to be of many hundred of years. Large earthquakes still cause important damage to cities and villages, sometimes with the loss of thousand of citizens.