Source Characteristics of the Egyptian Continental Margin Earthquake, 19 October 2012

Abstract

On 19 October 2012, at 03:35:11.2, an earthquake of m b 5.1 (European Mediterranean Seismological Centre [EMSC]) occurred in the passive continental margin of Egypt within the Nile Cone (Fig. 1a, Table 1). This event is considered the largest offshore earthquake in the last 57 years. Because much high‐quality data are recorded on modern digital instruments, we can make a more detailed source analysis. Figure 1a shows the locations of the seismograph stations in Egypt and the surrounding countries that recorded the earthquake. The same zone was attacked by a significant earthquake with M s 6.7 on 12 September 1955. The 1955 event caused notable damage over the Nile Delta and Alexandria. The focal mechanism solution of Costantinescu et al. (1966) for this event (Fig. 1b, Table 2) indicates a strike‐slip faulting mechanism with a considerable reverse component along a northeast or east‐southeast‐striking plane. The east‐southeast‐striking plane yields a right‐lateral motion whereas the northeast reflects left‐lateral offset. Figure 1. (a) View map of tectonic boundaries of the Eastern Mediterranean region (cited from Hussein et al. , 2013) and the seismic stations that recorded the 19 October 2012 earthquake. Acronyms: ERA, Eratosthenes Seamount; FL, Florence; IB, Ionian basin; MR, Mediterranean Ridge; LEV, Levantine basin; BAR, Bardawil; HA, Hellenic Arc; AS, Aegean Sea. Open triangles, Egyptian National Seismological Network (ENSN) stations; shaded squares, Greek stations; circles, refer …