Mapping and Analyzing the Volcano-Petrology and Tectono-Seismicity Characteristics Along the Syrian Rift – NW the Arabian Plate - Advances in Data, Methods, Models and Their Applications in Geoscience - page 150

In Syria, the Levant fault continues towards the North, between Damascus and Tartous, by
the Yammouneh fault. This last structure marks an important transition to the Palmyra
chain, making a sort of hinge between the northern and southern parts of the rift. The rift
continues to the north through the El Ghab basin, and it disappears in the Taurus zone, in
Turkey, in the Maras's triple junction point which relays Africa-Arabia-Eurasia. Many
arguments, from structural analysis and field observation, in addition to satellite imagery
data, and geomorphologic analysis, point to a recent, up to present day tectonic activity
along this structure, e.g. mylonites and fine-grained shear zones, filling of pull-apart basins,
deformed small active ravines and formation of scarps.
The Syrian rift corresponds to a transform fault, with lateral displacements decreasing from
more than100 Km, to the South, to less than 30 Km, to the North, at the level of the
Yammouneh fault (Walley 1988).The secondary faults and fractures deduced by the satellite
images (Bilal1994 a,b) ,and detected in the field (Lovelock 1984,Sawaf et al. 1993),support
this results, but more studies are needed to more explore others factors.
Many faults, as shown by the structural analysis and field observation, in addition to
satellite imagery data and geomorphologic analysis, attest that have recently been or are still
active along the Syrian rift. This is notably indicated by several phenomena: 1) the local
transformation of basaltic rocks into mylonites and fine-grained shear zones. Carbonate
basement rocks may also be deformed; they are more mylonitic because more easily
fragmented than basalts. 2) The occurrence of pull-apart basins filled with quaternary
sediments. 3) The deformation of small active ravines, with the formation of scarps
(Chorowicz et al.2005, Bilal 2009a, b).
4.2 Seismology
Syria, the northern part of the Dead Sea Fault Zone (DSFZ), has a long record of active
seismicity (Taher 1979, Al Tarazi 1999). Field observations, physical effects on ancient
building structures and movement analysis show that tectonic is still active at present time
(Khair et al.2000, Meghraoui et al2003, Chorowicz et al 2005).
Most major seisms in Syria occur in two regions: Either within or close to the rift zone, along
a North - South direction, or SW - NE oriented, along the Damascus Palmyra mountain
chain. This last domain does not contain any volcanic activity. Earthquakes in this region
can only be caused by superficial deformation of the sedimentary cover.
Many of seisms take place within the litohsphere, in response to active fault displacement
(Lay and Wallace1995,Yeats et al.1997) ,but others could also originate when the crust is
subducted into the mantle, or along rifts in response to an ascending hot spot (plume) (Yeats
et al.1997,Bilal and Sheleh 2004).This is precisely what may happen in Syria. The study of
volcanic xenoliths has identified a hot spot under the Arabic plate (Stein and Hofman 1992,
Sharkov et al.1993), starting during Cretaceous and ascending continuously until present
time (Bilal and Touret 2002, Bilal and Sheleh 2004). This part aims to analyzing the
seismicity distribution in the Syrian territory, using tectonic activity, laboratory
measurements, and historic and recent earthquakes records. It will also attempt to compare
these data with volcanic parameters.
4.2.1 Seismic parameters
The movement rate-displacement along a given fault could be estimated in the region of
Homs, where important basaltic eruptions took place 6 Ma ago (Sharkov et al.1994, Butler et