Vol.5, No.9, 1019-1024 (2013) Natural Science
Time-seismicity evolution and seismic risk
assessment of the Arabian plate
Ahmad Bilal
Damascus University, Damascus, Syria; bilka@sec-net.org
Received 30 April 2013; revised 30 May 2013; accepted 7 June 2013
Copyright © 2013 Ahmad Bilal. This is an open access article distributed under the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The seismicity of the Arabian plate, which is the
aim of this paper, is controlled by the Zagros-
Taurus collision zone in the North, the Indian
expansion zone and the Arab golf in the South
and the East, the Dead Sea Fault, the North con-
tinuity of the Red Sea, and the Syrian rift, which
links the rigid Arabian plate to the mobile ophio-
lite belt of Cyprus-Southern Turkey in the West.
These major elements with their related fracture
system, make the Arabian plate an important
seismic centre. To atta in our purpose, a variable
methodology is used in: measurements of
movement rate-displacement in the field, the
analysis of historical and recent seismic data,
and physical effects on the structures. The
movement rate-displacement, calculated in the
field by different specialists, varies from 2 to 6
mm/year. This rate increases from 2 - 3 mm/year
in the North, to 6 mm in the South. These esti-
mations are confirmed by historical seismic dat a,
the recent seismic recorded by the Arab seismic
centers, and physical effects on the building
structures in the region. The analysis of his-
torical and recent seismic data recorded in the
seismic centre show that the seismicity in this
plate, tend to fade out with time. This result is in
agreement with recent estimations on the move-
ment rate, and in line with the decrease of major
seismic intensity, which has occurred during the
last millennium. A conclusion of time-evolution
seismicity is traced, and a seismic zoning map,
for the Arabian plate, using movement rate, seis-
mic data, and tectono-geodynamic analysis, is
Keywords: Arab Plate; Seismicity-Time Evolution;
Seismic Risk Map
The European and African continents are crossed by
several N-S-trending rifts, all together forming major
structural features of the whole Earth: From North to
South, firstly the Oslo Permian rift (Norway), is continued
by the Neogene fracture system of Central-Southern Ger-
many (Eifel, Rhine Graben), then the rift system of French
massif Central and Rhone valley, ending finally with the
great Africa rift, which is the major structure of the Arab
These major crustal fractures, extending down in the
underlying mantle, have been active at different times,
repeatedly keeping the same approximate N-S direction
[1]. Periods of major activity are marked by extensive
volcanism, with a distinct tendency to show younger ages
southwards: Permian in Norway, Neogene in Germany,
Neogene to sub-actual one in the France, actual (present-
day) one in Africa. These ages correspond mainly to the
initial stage of rift-forming, whereas more ancient acci-
dents (e.g. Norway) could repeatedly play again, at each
phase of crustal extension.
In the Arab plat, the Dead Sea Fault, and the Syrian
rift, which links the rigid Arabian plate to the mobile
ophiolite belt of Cyprus-Southern Turkey [2,3], play a
very important role in the regional geodynamic structure
[4,5]. They make, with their related fracture system, this
sous-plate an important seismic centre (Figure 1). The
assessment and time-evolution of seismicity, in this plate,
are the subject of this research.
The Arabian plate roughly appears as a polygon, lo-
cated between the major African plate (including Nubian
and Somalian ones), and Eurasiatic and Indian plates,
respectively [1]. It is delimitated by the Red Sea in the
South-West, the Aden Gulf in the South, and the Zagros
and Taurus chains in the North and North-East, respec-
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A. Bilal / Natural Science 5 (2013) 1019-1024
Figure 1. Seismic zone in the Arab plate (Unesco, 1983).
tively (Figure 2).
The geophysical investigations confirms the typical con-
tinental nature of this plate, with an average crust thick-
ness of 40 Km, which changes, at the level of the Red
Sea at 250 KM, to less than 15 Km [6].
The Arabian plate presents three types of active bor-
- Convergent borders: the collision zone of Bitlis-Za-
gros [7-9], the subduction Makran-Oman between Aura-
sia-Arabia, and the Anatolian fault at the north-west of
the Arabian plate [10].
- Divergent borders: the oceanic rifts (Arabia-Nubia),
and the Aden gulf (Arabia-Somalia) [11].
- Transform borders: the senester faults of the Levant
(Arabia-Nubia), and the Dexter faults of Owen (Arabia-
India), in the West and the East [12].
This plate is marked by the Syrian rift structure, named
the Levant fault, corresponding to the northern part of
the Dead Sea fault zone (DSFZ), and in continuity with
the Red Sea rift zone [13].
The Arabian plate, with its world structure, Dead Sea
Fault zone and its South and North extremities, is an at-
tractive subject for the specialists, either their volcanol-
Figure 2. Geotectonic regional of the Arab plate (Bilal, 2005).
ogy [14,15], or either, and especially, their seismology
[16-21]. 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.
3.1. Seismicity-Time Evolution
The repetition of an earthquake (frequency return pe-
riod of an earthquake in the same locality), namely the
seismic cycle is controversial [22,23]. However, if an
earthquake is unique for a given locality, the destruction
of earthquake activity with time is of major importance.
In order to understand the seismicity-time evolution,
an investigation study on the historical, and recent seisms
has been executed.
For the historical record of ancient earthquakes, only
were used these verified by different sources [24,25].
Available historical data covers a wide period with vari-
able magnitude: Ancient time between 750 and 1800, with
magnitude estimated at 7.5 - 6.5 [21], it becomes 6 - 5
between 1800 - 2000 [25-28], less than 5 for the period
of 1960 to 2000 and between 4, 9 - 4 at present [18].
For recent seisms, we have collected good data, espe-
cially from the physical effects on the structures and the
station seismic centers (Figure 3). They are distributed in
the whole of the countries and in the off shore.
The results are represented by the histogram of Figure
4. They show that the seismic intensity tends to decreases
with time, in agreement with recent estimates on the
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A. Bilal / Natural Science 5 (2013) 1019-1024
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Figure 3. Structure of the Syrian rift and Dead Sea Fault Zone, from the satellite image, Landsat 2005, and epicenters of
the seisms in 2005-2006 after the Syrian seismic centre.
movement rate [21]. tectonic parameters [6,12,13,26], the historical and re-
cent 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 Ara-
bian plate is proposed (Figure 5). It distinguishes be-
tween three seismic zones: zone 1, associated with the
active tectonics of the DSFZ, and the collisional and ex-
tensional 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 need
to more verification by a qualified team.
3.2. Movement Rate-Displacement
The movement rate-displacement calculated by dif-
ferent 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 esti-
mates 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). 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]. 4. CONCLUSIONS
3.3. Assessement Seismic Risk—A Seismic
Zonation Map The Arab plate includes one of the world structures,
the Dead Sea Fault Zone (DSFZ), the continuity of Red
Sea in the North, and the Syrian rift to its northern part.
Structural analysis using variable techniques attests that
Using data obtained on the movement rate displace-
ment, by deferments sources [16,21,28,29], the seismo-
A. Bilal / Natural Science 5 (2013) 1019-1024
Figure 4. Seismicity-time evolution, after their magnitude and their age.
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A. Bilal / Natural Science 5 (2013) 1019-1024 1023
Figure 5. A seismic zoning map of the Arab plate. Zone 1, the highest seismic intensity zone; zone
2, the intermediary one and zone 3, the lowest one.
many faults have been recently or are still active to oc-
currence along this structure. Most major seisms in the
plate occur along this structure.
Historical seismic data and recent seisms recorded in
the seismic centre provide information indicating that the
seismicity in this plate tends to fade out with time, in line
with the decrease of major seismic intensity which has
occurred during the last millennium.
A seismic zoning map for the Arab plate, using seismic
data, and tectono-geodynamic analysis, is established. It
distinguishes three seismic zones. The highest seismic
zone intensity is associated with the world structure of
the Dead Sea Fault Zone with its two extremities, and the
Red Sea and the Syrian rift in the South and the North.
The lower seismic intensity zone setting is in the centre
of this plate.
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