Seismic Risk at the Dead Sea

The Dead Sea region is famous for its cultural diversity, its beautiful scenery, its gastronomic specialties and as the cradle of the Abrahamic religions. A popular tourist attraction is the Dead Sea itself, inviting visitors with its salinity of up to 33% for a unique bathing experience. What many tourists, and unfortunately also some residents of the region, don't know, is that the Dead Sea is located on one of the most active tectonic regimes in the Middle East.

The largest tectonic fault zone in the region spans from the Red Sea at the southern tip of the Sinai, along the Gulf of Aqaba, and through the Dead Sea until it reaches the East Anatolian fault system in Northern Syria. It is a so-called transform fault system, which means that the Sinai sub-plate and the Arabic plate move along this fault in opposite directions, with the Sinai sub-plate moving with respect to this fault towards the south and the Arabic Plate towards the north.

With a velocity of roughly 4-6 mm per year, the two plates are moving relatively slow compared to other regions (e.g., the Pacific Plate subducts close to Japan at a rate of 20-30 mm per year). Due to this slower movement, strong earthquakes are relatively rare. The last large damaging earthquake in the region occurred in July 1927 close to Jericho. It had a magnitude of Mw 6.1 (Moment magnitude scale). Hundreds of people lost their lives and extensive damage was observed in the surrounding cities. In November 1995, a strong earthquake of magnitude Mw 7.2 further south in the Gulf of Aqaba reminded us of the fact that stronger earthquakes are possible in the region. Fortunately, the event occurred in a less densely populated area and thus caused little damage.

Since the last damaging earthquake is now almost 90 years in the past, the population's awareness of such threats has decreased from generation to generation. Furthermore, an even larger problem is that the governments have not paid close enough attention to this threat and thus for a long time building practices were in use not considering the earthquake threat. Hence, nowadays's buildings could suffer significant damages from even rather small earthquakes in the vicinity (e.g., Levi et al., 2015, EUROCODE8).This high earthquake threat in combination with the strong population increase in the last century and the vulnerable building stock yields a very high seismic risk, i.e., a very high earthquake damage potential for the region.

At the Center for Early Warning Systems (EWS) of the German Research Center for Geosciences (GFZ), scientists thus work together with Israeli, Jordanian and Palestinian colleagues within the framework of the virtual institute DESERVE of the Helmholtz Association to assess the seismic risk in the cities of Eilat, Kerak, Madaba, Nablus, Ramallag and Tiberias. In a first step, a seismic hazard model, describing in a probabilistic way the occurrence of ground-shaking due to earthquakes, was derived for the region around the selected locations. Making use of a Mobile Mapping System developed at the EWS and successfully applied in Central Asia, within the next few months data on the building inventory of these cities will be collected and processed. On the basis of this information, stemming from a panoramic camera, it will be possible to assess the building inventory as well as to estimate its susceptibility to ground shaking for each of the cities in some detail. Combining these findings with the hazard model and the simulation of different earthquake scenarios, it will be possible to assess and estimate the spatial distribution of the seismic risk for these locations.

On a long-term scale, only seismic strengthening of existing buildings and replacing especially vulnerable buildings with more modern structures can reduce the seismic risk. The central tasks of these research efforts of scientists are thus to
a) provide an overview of the risk to decision makers in order to allow for a step by step risk reduction program and
b) to provide damage scenarios, which will assist in planning for the effective allocation of emergency resources.