The Syrian National Seismological Network (SNSN): Monitoring A Major Continental Transform Fault

Abstract

The twenty-seven-station digital short-period (1 Hz) Syrian National Seismological Network utilizing a combination of radio-frequency (RF) and land-line (LL) telephone telemetry was installed and has been operational since 14 January 1995. Augmenting the seismic network is a twenty-station network of three-component digital accelerographs commissioned at the same time as the seismic network. The spatial distribution of both networks covers most of western Syria from north to south. The network's design criteria were to monitor all discernable earthquake activity along the Dead Sea fault system (DSFS) and its related branches in Syria and nearby Lebanon (Figure 1). This major fault system is characterized by relatively high seismic activity and, as the Program for Assessment and Mitigation of Earthquake Risk in the Arab Region (PAMERAR) initiative proposed in 1981 concluded, poses a significant seismic hazard to the densely populated areas surrounding it. The most recent and truly devastating large earthquake (deaths estimated at 20,000) along this fault system occurred in the Bekaa Valley within the large restraining bend on 25 November 1759 and had an estimated magnitude of greater than Ms 7.3 (Ambraseys and Barazangi, 1989). The Syrian territory has been affected in the past by many large earthquakes that occurred along the DSFS. During the last millennium, between 1022 and 1872, at least ten large earthquakes occurred in this zone (Sbeinati et al. , 1997), as did the recent 1995 Ms 7.3 Aqaba earthquake, which may have remotely triggered an earthquake swarm in southwestern Syria (Mohamad et al. , 2000). Figure 1 shows a plot of the most destructive historical earthquakes in Syria in addition to the 1995 Aqaba event. Some of the historic events were larger than Ms 7.3 (Ambraseys and Barazangi, 1989). In 1985 the General Establishment of Geology and Mineral Resources (GEGMR), …