Seismicity and volcanism in the rifted zone of western Syria

Abstract

At the northern part of the Dead Sea fault zone (DSFZ), in the continuity with the Red Sea, Syria has a long record of active seismisity and recent volcanism. Field observations, physical effects on ancient building structures and movement analysis show that tectonics is still active at present time. A seismicity map has been established, based on the analysis of historic and recent seismicity, seismic parameters and laboratory oedometric experiments. The movement rate along the Syrian rift is estimated at less than 1 to 2.7-3.3 mm/year, with a seismic acceleration coefficient (Z) of 0-0.25 cm/S 2 .The whole Syria territory is divided into five seismic zones of decreasing intensity, from 1 to 5, respectively. Earthquakes may occur in the whole country, but most epicenters, with the highest magnitude, are located within the first two seismic zones, including the Syrian rift and associated volcanism. A closer comparison with structural-petrological data shows, however, this recent volcanic activity, issued from a shallower mantle source, tends to distantiate from the rift zone. Major seisms appear to be related either to ancient, extinct volcanoes (Cretaceous age) or to superficial deformation of the sedimentary cover. Their intensity has significantly decreased during the last millennium.

Time-seismicity evolution and seismic risk assessment of the Arabian plate

“…They show that the seismic intensity tends to decreases with time, in agreement with recent estimates on the movement rate [21]. tectonic parameters [6,12,13,26], the historical and recent seismic data recorded by the seismic centers [12,23,24,26], and the extrapolation of the assessment seismic risk of the northern part of the Arabian plate, established by Bilal (2009a) [16], a seismic zoning map for the Arabian plate is proposed ( Figure 5). It distinguishes between three seismic zones: zone 1, associated with the active tectonics of the DSFZ, and the collisional and extensional other zones, the highest seismic zone intensity with major damage risk; zone 3, zone of low seismic intensity, which occupies the core of the whole plate, with lowest potential risk, and zone 2, the intermediary zone with intermediary potential risk.…”

“…These results are confirmed by physical effects on the building structures in the region (field measurement on houses, measurement by Bilal, 2004). It is accepted that the average value increases from 2 -3 mm/year, in the North [16,21,29], to 4 -6 mm/year in the South [30].…”

“…Structural analysis using variable techniques attests that Using data obtained on the movement rate displacement, by deferments sources [16,21,28,29], the seismo-OPEN ACCESS OPEN ACCESS Figure 5. A seismic zoning map of the Arab plate.…”

“…The Arabian plate, with its world structure, Dead Sea Fault zone and its South and North extremities, is an attractive subject for the specialists, either their volcanol- ogy [14,15], or either, and especially, their seismology [16][17][18][19][20][21]. Three parameters define the seismicity of the Arab plate: the time-seismicity evolution, the movement rate, and the assessment seismic, which they will be briefly analyzed.…”

“…The movement rate-displacement calculated by different methods vary from 2 to 6 mm/year: it is 2.7 -3.3 mm/year along the Syrian rift [16,29], in line with estimates along the Wadi Araba fault, in the northern part of the Levant fault (4.6 +/− 2 mm/year, with a decreasing value of 2.3 mm/year for the last 12 ka [22], and 4.1 -6 mm/year in different areas along the Arab plate [28,30]. These results are confirmed by physical effects on the building structures in the region (field measurement on houses, measurement by Bilal, 2004).…”