Results of a microearthquake study,one year before the El Asnam earthquake of October 10, 1980

In November 1979, five portable instruments were installed in the El Asnam area. During a ten-day recording period, nine events of magnitude 0.5 to 1.9 were located in the focal region of the 1980 earthquake. All but one of the events occurred in the north western block defined by the main fault. A composite fault-plane solution agrees with the mechanism of the main shock. No abnormal behaviour of the $\text{V}{}_{\mathrm{p}}\text{V}{}_{\mathrm{s}}$ ratio was observed.