Statistical Study of Earthquake Swarms in Northeastern Algeria with Special Reference to the Ain Azel Swarm; Hodna Chain, 2015

Abstract

Northeastern Algeria is known by its high seismic activity as reflected by several hundreds of events occurring every year. Recently, this area has been the seat of several seismic sequences such as the 2010 Beni-Ilmane earthquake sequence and the 2012–2013 Bejaia earthquake sequences. On the other hand, it is also observed that the seismic activity of this part of Algeria is dominated by swarms, with high concentrations in time and space, from a few days to several months, ranging from a few kilometers to ten kilometers, and sometimes showing a migration of several kilometers in several weeks. The earthquake swarms are related to the increase in the water body of the reservoir after a heavy precipitation (Beni-Haroun (B-H) dam on 2012), and to the increase in the interstitial pressure due to the fluid injection (the 2007 Mila crisis and Grouz reservoir crisis) or due to the water circulation in hydrothermal systems (Ain Azel, El-Hachimia, Azzaba and Djemila swarms). Here, 10 swarms occurring in the region were analyzed using statistical laws, and finally the results have been discussed.