2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Paper ID: 44
Correlation between Seismic Activity and Tectonic Elements
In Northwestern Iraq
Hekmat S. AL-Daghastani*
Remote Sensing Center
Mosul University / Mosul / Iraq
ABSTRACT: The fundamental framework of the structure and stratigraphy of northwestern Iraq
is strongly influenced by the positioning of the country within the main tectonic units of the
Middle East, the Arabian plate and Eurasian plate, since Miocene episode of continental
collision. The study area is an integral part of the western Zagros Fold – Thrust Belt of the Iraqi
territory, which is characterized by narrow and longitudinal anticlines separated by broad
synclines. Many of the anticlines are affected by longitudinal thrust and strike - slip faults.
Continuous faulting and vertical block movements have been occurring since the Paleozoic and
continued intermittently up to Late Tertiary. The area is characterized by an en-echelon
anticlinal fold system, which gives to a relief with a general orientation of NW-SE and E-W
respectively. Some major faults trend parallel to the fold axes and other dissect diagonally
across the axes are very significant in neotectonic movements’ activity throughout the study
area. Some of these faults are marked by a conspicuous northeasterly trending concentration of
earthquake epicenters, which may cause many problems to any existing structures or those,
which will be built in the future.
Analysis of Landsat TM imagery and location of epicenters and magnitude of earthquakes for
the last (100) years ago, with some field observation, were utilized to draw a new
seismotectonic map of the study area. The relation of these faults with the other geological
structures clarified by constructed a specific morphotectonic map for this purpose at scale of
(1:250,000). This map is used to provide locations of earthquake risk throughout the region and
can be regarded as a database, which can greatly reduce the severity of the consequences on the
community. Many potential areas for active deformation and hazards geological features are
detected too.
Keywords: Iraq, Seismic activity, Tectonic.
*E-mail: hekmat_daghastani@yahoo.com
1. Introduction:
Iraq is located near the northern tip of the Arabian plate, which is advancing northwards relative
to the Eurasian plate, and is predictably, a tectonically active country. Manifestations of the
tectonism are earthquakes, neo-active faults and folds (Jassim and Goff, 2006). Earthquakes
generally occur within well-defined areas of the world, on which there is a striking pattern of
continuous belts of activity. Modern theories of the structure of the earth identify these belts as
the boundaries of mobile plates. Movement of one plate with respect to another causes stress
and deformation at the boundary. The rocks accumulate strain which is periodically released by
the failure or breaking of large blocks of crust, generating earthquakes. To the north of Iraq, the
two plates (Arabian and Anatolian) are in direct, head on collision, resulting in north-south
thrusting in the Caucasus and along Bitlis suture in the eastern Taurus Mountains. Seismic
activity in this region consists of scattered shallow, med- to high intensity earthquakes. The
latest quakes in eastern Turkey is located 16 km NNE of (Van city) measuring 7.2 on the
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Richter scale occurred on the 23 October 2011, at 20 km depth, followed by hundreds of
aftershocks, one of them located inside northern Iraq of (Bibo area) measuring (5.2) on the 27th
of October 2011 (www.vaneqs2013.com).
On both sides of this zone, two micro plates are being extruded sideways. The Anatolian
microplates is moving westwards, bounded by the North and East Anatloian faults. The central
Iran microplate is moving eastwards and rotating clockwise. It is bounded to the southwest by
the Zagros and to the north by Alborz Orogenic belts. The boundaries of the microplates are
broad zones of distributed deformation, rather than discrete line. Earthquakes and other
indicators of active deformation occur across the whole width of these boundary zones
(Beydoun,1991).
According to (Jassim and Goff, 2006) Iraq can be dividing into three tectonically different
regions (Fig.1)
- Stable shelf
- Unstable shelf
- Zagros suture zones
Mosul Governorate lies in the Unstable Shelf of the Arabian platform. The Unstable Shelf is
characterized by structural trends and facies changes that are parallel to Zagros- Taurus Suture
Belt, and can be divided into three tectonic zones.
1.1. Foothill Zone
The Foothill Zone is characterized by long anticlines with Neogene cores and broad synclines
containing thick Miocene-Quaternary Molasse. Generally, the area rises in elevation towards
north and northeast, reaching to more than 1460m (a.s.l.). Many outstanding mountains form
conspicuous geomorphological features within wide flat terrain like Sinjar ,Qara Chouq,
Maqloub, and Ain AL-Safra Mountains, whereas, the flat terrain form many well known plains,
like Rabeea, Jazira , Makhmour and many others. The south west boundary of the Foothill zone
lies along the south west limb of the impressive anticlinal line of Makhul and Hemrin. North of
Hatra city the boundary of the zone runs along the Tharthar valley then westwards into Syria
along the southern limb of Sinjar anticline. The zone comprises two longitudinal units, the
Makhul-Hemrin subzone in the southwest and Butmah-Chemchemal subzone in the northeast
(Jassim and Goff, 2006). Many major faults, which are considered as transcurrent faults, have
influenced the deformation of the Foothill zone area, for example, Mosul and Greater Zab River
faults are one of them.
1.2. High Folded zone
The High Folded Zone is characterized by anticlines of high amplitude with Paleogene or
Mesozoic carbonate exposed in their cores. The zone was uplifted in Cretaceous, Paleocene and
Oligocene time but was also the site of an Eocene molasses basin. Most of the Dohuk
governorate lies in this zone (Fig.1). Many major faults, which are considered as transcurrent
faults, have influenced the deformation of the High Folded Zone area, for example, SinjarDohuk faults are one of them.
1.3. The Imbricated Zones
This zone is characterized by imbricated structures with overriding anticlinal structures. The
Northern thrust (Ora) zone located at northern Dohuk area is an uplifted zone which developed
along the plate margin during the Cretaceous and is characterized by thrusted anticlinal
structures (Buday and Jassim, 1987).
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Fig. 1 :Tectonic Map of Northern Iraq after (Jassim and Goff, 2006)
The Balambo-Tanjero zones formed a basin near the plate boundary, which subsided strongly
from the Tithonian on wards. It was filled in by thick fluvial and marine clastics from
Masterichtian time on wards.
2. Seismological map:
A simplified morphotectonic map of the study area is compiled (Fig.2). This elicits the spatial
distribution of the main geomorphologic units and related morphologic features. These features
reflect the main geological structural reliefs and the action of different geomorphic processes
(Al-Daghastani, 2007).
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Earthquake epicenter distribution map of the north western Iraq has been drawn, using the
available recording data from the Mosul Seismological Observatory and other Iraqi
Observatories for the last (100) years ago (Al-Daghastani, 2011). These data has been utilized to
determine the seismic activity, location of epicenters and magnitude of earthquakes (on the
Richter scale), for the studied region. Evidently, the highest recorded magnitude in the studied
region from 1913 till 2013 is 5.9 degrees on the Richter scale, while the lowest recorded
magnitude is 2.6 degrees.
This information is used in conjunction with the analysis of geologic and geomorphic features
using Landsat TM imagery, which is available at the Remote Sensing Center, in Mosul
University (Fig. 2), supported by local field observations. These data were utilized to draw a
seismotectonic map of the Nineveh governorate and surrounding area, showing the relationship
between earthquake and epicenters and main geological features. This map has been used to
provide locations of earthquake risk throughout the region.
The present study revealed that the geomorphologic evolution of the study area was greatly
influenced by the last phase of intensive orogenic movement that took place during LateMiocene-Pliocene, and continued during Quaternary period with less intensity.
On of the most striking results of this analysis has been the discovery of numerous, previously
unmapped regional linear features (faults) in areas considered to be reasonably well mapped
(Fig. 2). Some of these lineaments are marked by a conspicuous northeasterly trending
concentration of earthquake epicenters just northeast of Mosul and Duhok cities. While the
author was writing this report and earthquake measuring 5.0 on the Richter scale occurred on
the 11th of march 2013 (Table 1), and was centered in north east of Mosul city (about 35 Km),
an area currently assigned a grade (three) earthquake risk rating. This area could be struck by
another earthquake any time similar to the moderate one which jolted the region. Thus, the
above grading may require reassessment.
3. Recent earthquakes:
The previous studies have showed that the Arabian plate is still moving towards the northeast
with a rate of 37 mm/y and the Orogeny has not ceased yet (Keller and Pinter, 2002). It means
that the compression phase of the Arabian plate is still active. However, faults in the Low and
High Folded Zones are also continuously active and displacement must be taking place too.
Consequently, the recent earthquakes in northern Iraq (Table 1), which is approximately
coincides with these major transcurrent faults (Lineaments), showing ongoing strike- slip
displacement that occurred along their trends (Fig.3).
Table 1. Recent earthquakes in the study area.
Date of quake
11-3-2013
13-3-2013
3-4-2013
Magnitude
5.0
4.3
3.7
Depth
9.1kg
11.kg
14.Kg
Lat. and longt.
(36° 33´ 29.”)- (43° 19´ 43.”)
(36° 35´ 41”)- (43° 24´ 13”)
(36° 18´ 12”)- (43° 15´ 31”)
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
earthquake epicenters
Fig.2 : Seismotectonic Map of North Western Iraq with Earthquake Epicenters
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Fig.3: The location of the latest Earthquakes in the Region
The type and orientation of the regional faults in the Low Folded Zone are quite compatible
with the direction of the regional compression and the direction of the tectonic transport.
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
While accommodating the regional shortening, strike-slip faults produced belt parallel
elongation too. Nevertheless, such faults exhibit more complicated fold-fault age relationship in
the zone (AL-Daghastini and AL-Dewachi, 2009).
4. Conclusion:
The main conclusions that may be drawn from this map are:
1. Morphotectoically, the primary tectonic force involved appears to have been horizontal plate
motion. The Alpine Orogenic force was translated into minor secondary tectonic movements
between basement blocks. These were both vertical (as reflected by changes in sedimentary
facies) and horizontal translational and rotational movements (reflected by changes in fold trend
and geometry). There fore, the tectonic and structural effects, beside the type of the exposed
rocks and climatic conditions have controlled the main morphotectonic units and geodynamic
processes in the involved area.
2. The study area is topographically divided into two main parts; the mountains part and the flat
and slightly undulated terrain. The geomorphic evolution was greatly influenced by the last
phase of intensive orogenic movements that took place during Late Miocene–Pliocene and
reached its climax during Early Pleistocene. During the Quaternary periods, the climate became
leading factor in controlling the geomorphologic processes, such as weathering, erosion and
fluvial processes, beside the lithologic, topographic and structural factors. Moreover, several
geological criteria indicate that the study area is neotectonically active and the deformation is
still operative at the present time.
3. Generally, the seismic magnitude of the northern Iraq is intermediate, in the range of 2.6 to
5.9 degrees on the Richter scale for the last 100 years, and the depth of seismic activity is
shallow.
4. The major geomorphic lineaments (Transcurrent faults) that trends NE-SW, across the Low
and High Folded Zones (for example Hutra- Upper Zap, Ajij- Mosul and Sinjar- Duhok) are the
well expressed effect by seismic activity in this region. These three lineaments, some of (60-80)
km long can probably include large earthquakes in this vicinity. In addition, caution must be
taken in planning for any future establishments around the zone of these three major lineaments.
5. This seismic and tectonic activity maps can be regarded as a database, in the improvement of
the modern structural concepts, and in the distribution of the earthquake epicenter in this
vicinity, which can greatly reduce the severity of the consequences on the community. The
Duhok and Mosul city councils must use such information to avoid building across these
hazards geological features. However, the hazard associated with known fault movement caused
by earthquake can be reduced in the new development area.
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5. References
Al-Daghastani, H. S., 2007. Geomorphic map of Nineveh Governorate, northwestern Iraq, using
visual image interpretation. Rafidain Journal of Sciences, 18: 1, 81-90.
Al-Daghastani, H. S. and AL-Dewachi, B.A., 2009. Evidences for discovering subsurface
structures using remote sensing data in Nineveh Governorate, northwest Iraq. Iraqi Bull. Geol.
Min. 5: 1, 36-46.
Al-Daghastani , H.S. 2011. Seismic map of Nineveh Governorate. Remote Sensing Center.
Mosul University, 2nd edition.
Beydoun, Z.R. 1991. Arabian Plate Hydrocarbon. Geology and Potential. A plate Tectonic
Approach. AAPG. Tulsa, Oklahoma, 77.
2013 INTERNATIONAL VAN EARTHQUAKE SYMPOSIUM
23 – 27 OCTOBER 2013 VAN, TURKEY
Buday, T. and Jassim, S.Z., 1987. The regional geology of Iraq. Vol.11. Tectonism ,
Magmatism and Metamorphism, Kassab, I.I.M and Abbas, M.J. (eds), 352.
Keller , F.A and Pinter , N. 2002 . Active tectonics (Earthquakes , uplift and landscape) prentice
hall , NJ. USA 362.
Jassim, S.Z. and Goff, J.C. 2006. Geology of Iraq. Published by Dolin, Prague an Moravian
Museure, Brno, Czech Republic, 341.
Www.vaneqs2013.com.