Arab J Geosci
DOI 10.1007/s12517-013-1135-7
Akhtar M. Kassi & Shuhab D. Khan &
Huseyin Bayraktar & Aimal K. Kasi
Received: 11 February 2013 / Accepted: 20 September 2013
#
Saudi Society for Geosciences 2013
Abstract The Makran accretionary wedge has a much larger number of mud volcanoes then those reported earlier. Using high-resolution satellite images, over 70 active mud volcanoes were identified. These mud volcanoes occur within a welldefined zone; we call it the Makran zone of active mud volcanoes (MZAMV), which is parallel to the regional trend of the accretionary wedge. Mud volcanoes within the zone occur as clusters, which form linear belts parallel to the regional thrusts associated with anticlines. The MZAMV zone also includes the offshore mud volcanoes occurring in the shallow shelf area, including the recurrently emerging mud islands. Several occurrences of thick deposits of old mud volcanoes (Pleistocene or even older) are also present within this zone, which also display recognizable features that are characteristic of the fossil mud volcanoes. We propose that the
MZAMV developed and evolved in response to the continued compression within the Makran accretionary wedge, which in turn, is a response of the subduction process. Mud diapirism has been an ongoing phenomena since Pleistocene or even earlier. The events of enhanced mud extrusion in mud volcanoes and/or emergence of island(s) have relevance with seismic phenomena and, therefore, may be closely monitored.
A. M. Kassi
Department of Geology, University of Balochistan, Quetta, Pakistan
S. D. Khan
Department of Earth and Atmospheric Sciences, University of
Houston, Houston, TX, USA
H. Bayraktar
Department of Geomatics Engineering, Erciyes University, Kayseri,
Turkey
A. K. Kasi (
*
)
Centre of Excellence in Mineralogy, University of Balochistan,
Quetta, Pakistan e-mail: aimal_kasi@yahoo.co.uk
Keywords Accretionary wedge . Cluster . Makran . Mud volcano
Introduction
Mud volcanoes are expressions of the ejection of mud, fluids, and gases from the rock formations in areas of highsedimentation rates and compressional tectonics, commonly in convergent margin settings. The extruded material forms characteristic isometric to elongate morphological features largely varying both in shape (elevated plano-conical to negative funnel-shaped) and size (from 100 km
2 to less than
10 m
2
) and composed of mud breccias sharply contrasting to the surrounding host sediments.
Mud volcanoes have been reported both onshore and offshore along the Makran accretionary wedge (Snead
1964
;
Tabrez et al.
1999
; Wiedicke et al.
2001
; Delisle et al.
2002 ,
Delisle
2004
), which is a south-convex arcuate belt of deformed, mostly mud-rich terrigenous Tertiary succession, although thrust-bound blocks of Cretaceous rocks have also been reported further northward (Hunting Survey Corporation,
1961
; Kassi et al.
2007 ). Some occurrences of the mud volca-
noes at the coastal belt of Makran, such as the Chandragup,
Jabel-u-Ghurab, and Khandawari (Fig.
1
) are already known
(Snead
1964
; Wiedicke et al.
2001
; Delisle et al.
2002 ; Delisle
2004
); however, we found a large number of mud volcanoes that have not been reported and/or described before, which occur in the form of isolated conical volcanoes, fields/ clusters, or elongated ENE – WSW to E – W-oriented ridges.
The gas- and water-charged onshore and offshore mud volcanoes extrude methane and higher hydrocarbon derivates
(Harms et al.
1982 ). Release of the pressure for their develop-
ment is commonly provided by fault zones and anticlines of the
Quaternary to Neogene sediments. They show variations in activity, which in some cases are concurrent with earthquakes

Arab J Geosci
Fig. 1 Landsat-5 TM (bands 3-2-1 displayed as Red Green Blue ) image of the coastal belt of Makran area showing positions of active mud volcanoes within the Makran Zone of Active Mud Volcanoes, and deposits of the old mud volcanoes
(Snead
1964 ; Wiedicke et al.
2001 ; Delisle et al.
2002 ; Delisle
2004
).
It has been proposed that fault activity may be the key player governing the rate of mud extrusion (Kopf
2008 ;
Bonini
2007
,
2008
). Even the location of mud volcanoes is sometimes used to infer the presence of active fault systems
(Lynch and Hudnut
2008 ). Relationship between earth-
quakes and enhanced eruption of mud volcanoes has also been analyzed at the Pede
–
Apennine margin of the
Northern Apennines and in Sicily (Jakubov et al.
1971 ;
Deville et al.
2003
; Bonini
2009 ). Mud volcanoes some-
times erupt within days after nearby large earthquakes
(Mellors et al.
2007
; Manga
2007 ; Manga et al.
2009 ;
Madonia et al.
2011
), but a correlation between these events is not always straightforward. Liquefaction typically occurs after earthquakes in shallow soils and is often manifested by sand volcanoes (Galli
2000 ). Liquefaction caused by
shaking (dynamic strain) has been proposed to be a potential mechanism for triggering the eruption of mud volcanoes expelling mud from depths exceeding a few kilometers (Manga and Brodsky
2006 ).
The active subduction and compression within the Makran accretionary wedge has been causing frequent seismic activity and mud volcanism. Three severe earthquakes occurred during the last 66 years, which also caused tsunamis as well as emergence of mud islands in the coastal belt (Sondhi
1947 ;
Tabrez et al.
1999
; Delisle et al.
2002 ; Delisle 2004 ).
The objective of this paper is to discuss several newly discovered occurrences of the onshore mud volcanoes and old mud volcano deposits in the coastal belt of Makran, using remote sensing techniques and field observations. Also, we aim to highlight their tectonic control and relevance with earthquake occurrences.
Geological setting
The Makran convergent margin comprises a wide accretionary wedge (Fig.
1 ), built up by the sediments scraped off the
Arabian Plate during Late Cretaceous to Early Paleocene
(Leggett and Platt
1984
; Platt et al.
1985
,
1988 ), which is
extremely thick with a gently (2
–
3 °) sloping subduction zone
(Harms et al.
1982
,
1984
; Kopf et al.
2001
). Accretion and underplating of the sediments caused uplift of the coastal belt and seaward migration of the coastline (White
1983 ; Platt
et al.
1988 ). Based on morphology, the Makran accretionary
prism has been divided into three domains (Kukowski et al.
2001 ; Schluter et al.
2002
; Ellouz-Zimmermann et al.
2007 ):
the accretionary wedge, the trench, and the Murray Ridge system.
The onshore accretionary wedge, comprising thousands of meters of sedimentary rocks of Cretaceous to Recent age, is arranged in east
– west-aligned subparallel ridges and valleys
(Table
1 ; Fig.
2 ). The succession consists mainly of the Late
Eocene
–
Early Miocene turbidite succession. Further inland thrust-bound inliers of the Upper Cretaceous
–
Eocene limestone, conglomerate, mafic rocks, purple and varicolored shale, chert and pelagic limestone are also present (Hunting
Survey Corporation,
1961 ; Cheema et al.
1977
; Kassi et al.
2007 , 2011 ) within the Late Eocene to Early Oligocene turbi-
dites. The younger sedimentary succession is exposed in the coastal belt of the accretionary wedge, which is composed of mudstone, cyclically interbedded sandstone and mudstone

Arab J Geosci
Table 1 Stratigraphic succession of the Makran Belt [modified after Hunting Survey Corporation
( 1961
; Cheema et al.,
1977 ;
Kassi et al.
2007
)]
Age
Pleistocene to Holocene
Upper Pliocene
Lower Pliocene
Upper Miocene
Lower Miocene
Oligocene
–
Miocene
Upper Eocene-Lower Oligocene
Eocene
Paleocene
Cretaceous
–
Paleocene
Group Formation Lithology
Makran group Haro formation Shelly and reefoid limestone, sandstone, and conglomerate
Unconformity
Ormara Formation Soft and poorly consolidated mudstone with minor sandstone
Unconformity
Chatti Formation Calcareous shale and marl
Hinglaj Formation Cyclic succession of sandstone and shale
Parkini Mudstone Mudstone with occasional thin sandstone
Turbat Group Panjgur Formation Sandstone interbedded with shale
Hoshab Shale Shale with occasional thin bedded sandstone
Thrust
Wakai Limestone Highly fossiliferous to reefoid limestone
Thrust
Ispikan Formation Conglomerate, sandstone, and minor shale
Thrust
Wakai mélange Agglomerate, purple shale, marl, chert, pelagic limestone, marble and mafic and ultramafic rocks and limestone succession (Table
1
; Fig.
2
; Hunting Survey
Corporation,
1961 ; Kassi et al.
2007
; Kassi et al.
2011 ).
Due to active subduction and compressive tectonism, the
Makran accretionary belt has frequent seismic activity mud volcanism. Severe earthquakes have occurred, which caused tsunami; enhanced extrusion of mud volcanoes and recurring emergences of mud volcano islands in the Arabian Sea near the coastal belt of Makran (Sondhi
1947
; Delisle et al.
2002 ;
Delisle
2004 ; Bilham et al.
2007 ). The accretionary belt
contains numerous onshore and offshore mud volcanoes, which provide a wonderful opportunity to further study the phenomenon of mud diapirism.
Materials and methods
The paper is based on the use of remote sensing techniques and field observations. Landsat-5 TM (bands 3-2-1 displayed as Red-Green-Blue) satellite images of the coastal belt of
Makran, specifically of the territory of the coastal belt of
Pakistan, have been used for navigation purposes in order to identify mud volcano occurrences. Field photographs of the mud volcanoes and their deposits in some parts of the Makran accretionary wedge have been used to further elaborate their morphological characteristics.
Results
The Makran zone of active mud volcanoes
Mud volcanoes occur at several localities in the coastal belt of
Makran near the towns/villages of Gawadar, Ormara, Kund
Malir, Bela, and Awaran. Using Google satellite images, we identified and plotted over 70 active mud volcanoes on the
Landsat-5 TM images of the coastal belt (Fig.
1 ; Table
2
), which indicates distribution within a well-defined zone
— we call it the Makran zone of active mud volcanoes (MZAMV).
Most of the mud volcanoes are currently active and their deposits show various (2
–
5) clear phases of flows. Deposits of the nearby mud volcanoes of the clusters coalesce to form thick mud volcano deposits. Also, mud volcanoes are distributed in 14 clusters/subclusters. The MZAMV is aligned parallel to the main trend of the south-convex arcuate accretionary belt and aligned along the major thrusts and anticlinal axes, specifically eastwards near the Ornach
–
Nal Fault System, where the
E – W-oriented Makran accretionary wedge bends toward

Arab J Geosci
Fig. 2 Geological map of part of the coastal belt of Makran (modified after Hunting Survey Corporation,
1961 ), showing major structural features and
their relationship with mud volcanoes and their deposits northeast (Fig.
1
; Table
2
). Here, quantity of mud extrusions is higher and distances of mud volcano clusters from each other are smaller as compared to those further westward. Dense occurrences of the mud volcanoes towards the east is in line with the eastward increasing rate of plate convergence, frequent occurrences of thrust-related anticlines, and faults having leftlateral strike-slip components near the Ornach – Nal fault system
Table 2 Characters of various clusters/subclusters of the active mud volcanoes based on satellite images
S. No.
Name of the cluster
7
8
5
6
3
4
1
2
9
10
11
12
13
14
South Chandragup
North Chandragup
West Chandragup
Jabel-u-Ghurab
North Khandewari
South Khandewari
Kund Malir
South Awaran Hills
North Awaran Hills
Sipai Sing
East Ormara
Central Ormara
West Ormara
Gwadar
(Figs.
2
and
3 ). Recognition of the MZAMV is in line with the
notion of Schluter et al. ( 2002
), that development and distribution of the mud diapirs and volcanoes are largely controlled by thrusts associated with asymmetrical anticlines (Figs.
2
and
3
).
The size and characters of the larger mud volcanoes, i.e., those recognizable on high-resolution satellite images, were studied. Coordinates, estimated covered areas, and diameters
No. of mud volcanoes
3
3
16
8
2
4
4
5
9
3
6
1
4
2
Range of covered areas (ha)
11.90
–
138.0
01.70
–
1921.0
43.70
–
64.5
0.60
–
02.6
0.09
–
308.2
41.00
–
163.4
0.04
–
118.6
0.03
–
265.7
0.13
–
336.2
0.19
–
10.21
0.63
–
20.92
10.5
0.06
–
00.47
0.11
–
00.46
Range of crater diameters (m)
22.5
–
145
9.0
–
118
108.0
–
112
1.5
–
11
13.5
–
110
Up to 138
1.0
–
4.5
1.0
–
10.5
1.0
–
7.5
5.0
–
85
1.0
–
67
1.0
–
30
1.0
–
6
1.0
–
7

Arab J Geosci
Fig. 3 Sections across the area showing major structural features and their relationship with mud volcanoes and their deposits of craters of the recognized mud volcanoes were measured and their visible characters briefly described (Fig.
1 ; Table
2
).
The mud volcanoes pierce the Early Miocene to Pleistocene mudstone-dominant successions. Most of the clusters/ subclusters have major vents having large covered areas of mud flows and a number of smaller satellite vents in the surroundings. In addition to the previously described
Chandragup, Jebel-u-Ghurab and Khandewari clusters
(Snead
1964
; Tabrez et al.
1999 ; Wiedicke et al.
2001 ;
Delisle et al.
2002 ; Delisle 2004 ), we also discovered a num-
ber of mud volcanoes within these clusters. We further discovered and named the Awaran Hills, Sipai Sing, Kund Malir,
Ormara, and Gwadar clusters after the nearby towns/villages of the coastal belt (Fig.
1 ; Table
2 ). They are described as
under: of mud extrusion, indicate 2
–
5 apparent phases of mud flows that are clearly visible on high-resolution satellite images.
The Chandragup-I has a crater of 20-m diameter filled with viscous fluidized mud. The mud bubbles up and sometimes burst violently in order to emanate hydrocarbon gases
(Fig.
4b ). Crater of the South Chandragup-II is a circular
water-filled lake, which is 2.5 m below the circular edge of its crater, showing very minor activity of gas bubbling and weak extrusion of muddy water in its central part (Fig.
4b ).
Circular walls of the crater are partly eroded and collapsed. It seems that mud extrusion has decreased currently, which caused the water level to drop within the crater and erode its older deposits. The Chandragup-III is 30-m high from the surrounding ground level and appears to have dried-up currently. Our data (Fig.
1
; Table
2 ) indicates that, instead of just
3
–
4 mud volcanoes, that were reported earlier (Stiffe
1874
;
Snead
1964
; Reimann
1989 ; Delisle et al.
2002 ), 11 more mud
volcanoes exist in the Chandragup area, which make up three subclusters of the South, North, and West Chandragup.
Chandragup cluster
In the Chandragup cluster, mud volcanoes are spread 2
–
8 km north of the coast east and southeast of the Hingol River and is considered as the largest active mud volcanoes of the region
(Table
2
; Figs.
1 ,
4a and b
). It comprises 11 mud volcanoes, along with some dried-up vents, distributed in three subclusters named as South, North, and West Chandragup. The West
Chandragup subcluster is 18 km northwest of the already known Chandragup (i.e., our South Chandragup subcluster)
(Snead
1964
; Wiedicke et al.
2001 ; Delisle et al.
2002 ; Delisle
2004 ). A number of small mound-like features are also pres-
ent, which were satellite vents that are presently not active.
Covered areas of the mud volcano deposits range between 1.7
and 1,921 ha (Table
2 ). Diameters of the craters range from 9
to 145 m. Diameter of the craters have no relationship with the size and covered area of the mud deposits. Most of the mud volcanoes (8 out of 11) of the North and South Chandragup clusters are presently active, i.e., extruding fluidized mud and hydrocarbon gases; however, they show fluctuations in extrusion activity. Mud deposits, by virtue of their episodic activity
Jebel-u-Ghurab cluster
The Jebel-u-Ghurab cluster of mud volcanoes (Fig.
1
) lies within the flat-lying Dhak Desert formed by playa-like sediments, 1 km west of the Dhak Anticline (Reimann
1989 ).
Because of their small sizes, only four mud volcanoes are recognizable on the satellite image (Fig.
1 ; Table
2
), although several small mound-like feature have been reported
(Reimann
1989
; Delisle et al.
2002 ). Mud volcanoes of the
Jebel-u-Ghurab range in covered area from 0.6 to 2.6 ha.
Diameters of the observed craters range from 1.5 to 11 m.
Delisle et al. (
2002 ) suggested that presence of these mud
volcanoes within the core of the anticline might be because of their relevance with this tectonic feature for concentration of gas near the crest of anticline. Also, fractures along the axis of the anticline may have provided passages for extrusion of
mud-water and gas. Delisle et al. ( 2002 ) further explained that

Arab J Geosci several small-size active mud volcanoes and mounds are present, which have elevations from 1 to 8 m and range in circumference from <5 to 50 m; some are dried-up others are water-filled. One of the mud volcanoes represent a hummocky hill with a flat top surface having several small mini-craters with bubbling of gas discharge and minor outflows of mud.
The larger mud volcano shows two subcircular water and mud-filled craters having lateral slumps (over-steepened mudflows) and fans of mudflows onto the adjacent playalike plain.
Khandewari cluster
The Khandewari cluster of mud volcanoes comprises six mud volcanoes located at the NNE
–
SSW-oriented Haro Range,
30
–
35 km northeast of the South Chandragup subcluster
(Fig.
1 ; Table
2
). Mud volcanoes within the cluster are oriented parallel to the strike of the range, however, they comprise the South and North Khandewari subclusters (Figs.
1
and
4c ).
One of the mud volcanoes in the North Khandewari subcluster is represented by a very large, circular cone-shaped mud
Fig. 4 Satellite images and field photographs showing mud volcanoes of the Chandragup, Khandewari and Kund Malir clusters; a Satellite view of the South Chandragup subcluster; note contrasting colors of various fluxes of mud flows of the same vent; blue colored mud shows the most recent flow, b field photographs of a mud volcano of the South
Chandragup subcluster, showing mud and gas extrusion and formation of huge mud bubbles, c close-up view of the mud volcanoes of the South
Khandewari subcluster; contrasting colors of various fluxes of mud flows are very clear, d close-up view of the main mud volcano of the Kund
Malir cluster with several satellite crates in the surrounding area

Arab J Geosci volcano deposit, which resulted from the outpouring of mud from one or more central vents. Presently, the cone seems to have been built from a series of dried-up and eroded mud flows.
Covered areas of mud volcano deposits of the Khandewari cluster vary between 0.09 and 308.2 ha (Table
2
). Diameters of the craters of the Khandewari cluster range from 9 to138 m; however, they have no relationship with the size or covered area of mud deposits. All six mud volcanoes of the cluster are active and extrude fluidized mud, however, they show recurrently active periods followed by periods of quiescence. Mud volcanoes, by virtue of their episodic activity, clearly show 2
–
5 phases of mud flows on the high-resolution satellite image.
Kund Malir cluster
The Kund Malir cluster is named after the village of Kund Malir, situated near the Makran Coastal Highway (Fig.
1 ), but not
mentioned or described before. The cluster is situated 4.5 km northeast of the Kund Malir village (Figs.
1
and
5c ; Table
2 ). The
cluster comprises 16 mud volcanoes, spread over a 5-km NE
–
SW-oriented strip along the southwestern side of the Malan
Range and arranged subparallel to the orientation of the range.
Covered area of the Kund Malir mud volcano deposits a range between 0.04 and 118.6 ha. Mud flows of most of the mud volcanoes coalesce with each other to form thick mud volcano deposits. Diameter, the largest crater within the Kund Malir cluster is 25 m. Generally the old mud volcano deposits cover larger areas as compared to their fresh mud extrusions (Figs.
1
and
4d ; Table
2
). All mud volcanoes of the cluster are active.
Ormara clusters
Although mud volcanoes have been mentioned to be present in the Ormara area (Delisle et al.
2002 ), they have not been
described before. The Ormara mud volcanoes are present in a flat area 9 – 10 km north – northeast of the coastal town of
Ormara, south of the Gurad Hills (Figs.
1
and
5a ). They are
distributed in three subclusters, spread over a 9-km long and
2.5-km wide area, having east
– west orientation generally parallel to the regional trend (Fig.
1
; Table
2 ). Eleven mud
volcanoes have been recorded in the cluster, which range in a covered area between 0.63 and 20.92 ha. Covered areas of the large mud volcanoes also include several (in some cases up to
25) small mounds/satellite craters. Crater diameters range between <1 and 67 m. Almost all mud volcanoes listed in the Ormara cluster are active.
Gwadar cluster
Mud volcanoes have been reported near the coastal city of
Gwadar (Delisle et al.
2002
); however, they have not been described before. A cluster of mud volcanoes is present 9 km north
– northeast of the Gwadar town near the western edge of an east
– west trending hill, 3 km south of the Gwadar Airport
(Figs.
1 ,
5a and b ; Table
2
). On the high-resolution satellite image, two mud volcanoes may be seen along with some mud mounds in the nearby surroundings (Fig.
5a
). The main mud volcano has a covered area of 0.47 ha and a small crater lake of 7-m diameter. A nearby mound covers an even smaller covered area of 0.11 ha and does not seem to be active. Some very small mud volcanoes have also been reported by the local community; however, they are not large enough to be observed on satellite image.
Awaran Hills and Sipai Sing clusters
The Awaran Hills and Sipai Sing clusters of mud volcanoes have not been mentioned or described before. Over 20 mud volcanoes are present in the Awaran Hills west and southwest of the town of Bela (Fig.
1 ; Table
2 ). Mud volcanoes are
spread over a 58-km long N
–
S-oriented strip generally parallel to the strike of the Awaran Hills and grouped into the South and North Awaran Hills and Sipai Sing subclusters. Their covered areas range from 0.03 to 336.2 ha. Most of the mud volcanoes in the Awaran Hills clusters are active and their crater diameters range between <1 to over 85 m. The Sipai
Sing subcluster comprises three mud volcanoes present within a vast area (18 km
2
) of old mud volcano deposits near the
Sipai Sing area, 45 km east of the Awaran (Fig.
1 ; Table
2
).
Two mud volcanoes of the Sipai Sing subcluster have the largest crater diameters among the Awaran Hills and Sipai
Sing clusters, having crater diameters of 85 and 13.5 m, respectively. Mud volcanoes of these clusters are mostly active showing 2
–
5 clear phases of mud flows. Mud flows of the adjacent mud volcanoes coalesce to form thick deposits.
Discussion
In addition to the four mud volcanoes reported by the previous workers (Snead
1964 ; Wiedicke et al.
2001 ; Delisle et al.
2002 ; Delisle 2004 ), we have identified and described the
South Chandragup subcluster and the South Khandewari subcluster. Our data (Fig.
1
; Table
2
) indicates that 11 mud volcanoes are present in the Chandragup area, making three prominent subclusters. Furthermore, we have reported six mud volcanoes within the Kundewari cluster.
The Kund Malir cluster, comprising 16 mud volcanoes, and
Awaran Hills and Sipai Sing cluster/subclusters, comprising 20 mud volcanoes, are hereby reported and described for the first time. (Table
2 ; Fig.
4d ). Also, we have reported 13 mud
volcanoes in the Ormara area, comprising 3 prominent subclusters, and a cluster of 4 mud volcanoes in the Gwadar area
(Figs.
1
and
5 ; Table
2
). The plot shows that mud volcanoes and their deposits are distributed over a much wider area of the

Makran accretionary wedge (Fig.
1
; Table
2 ) than those report-
ed earlier (Stiffe
1874 ; Snead 1964
; Reimann
1989 ; Delisle
et al.
2002
) and that mud volcanoes are more common within the eastern part of the accretionary wedge.
Old mud volcano deposits
In addition to the onshore and offshore occurrences of mud volcanoes, several occurrences of old mud volcano deposits are present in the coastal belt of Makran (Fig.
1
), which may be as old as Pleistocene (or even older). Old mud volcano deposits comprises greenish gray to bluish green mudstone found in the Haro Range, Awaran Hills, Malan Range,
Kappar, and Barambah (north of Gwadar) and several other localities. Occurrences of the old mud volcano deposits
(Fig.
1 ) indicate that they are part of the MZAMV and parallel
to the regional trend of the accretionary wedge. However, the old mud volcano deposits are also spread further north of the
MZAMV.
On a road-side exposure 46 km northeast of the coastal town of Gwadar, 4 km north of the Kappar village, the
Pliocene mudstone has been dissected by streams and interesting features of the old mud volcanoes are exposed over a wide area. They include vertically oriented cylindrical chimney-like features of variable diameters (up to 3 m in diameter) and a network of smaller branched cylindrical features of different orientations (Figs.
5d, e ). These features
indicate that mud extrusion has been a widespread phenomenon during Pliocene. The Hunting Survey Corporation (
1961 )
termed one unit in a north
– south section along the Hingol
River as "extrusive mud formation" (Figs.
2
and
3 ) and sug-
gested that during the past, huge amounts of gas- and watercharged mud were extruded to the surface, in analogy to circular mud volcanoes, and emplaced along fault structures
(several tens of kilometers long) unconformably into the Early
Pliocene mudstone succession (Hunting Survey Corporation,
1961 ; Bannert et al.
1992
). Figures
2
and
3
indicate that the active mud volcanoes and the old mud volcano deposits, the
"extrusive mud formation" of the Hunting Survey Corporation
( 1961 ), are clearly related with the asymmetrical anticlines of
the coastal belt of Makran. The thrusts had been providing passages for the extrusion of water mixed with mud and gas and the mud being derived from older mud-rich succession of
Parkini Formation.
The old mud volcano deposits are common within the
Pliocene mudstone succession further inland in the Makran coastal belt (Figs.
1
, 5d, e). We have identified and mapped several occurrences of old mud volcano deposits within the coastal belt of Makran (Figs.
1
and
2 ), which suggests that
mud volcanism had been a widespread phenomena during the past, and that some mud volcano deposits may be Pliocene or even older. Earlier publications have not differentiated between mud volcanoes sensu stricto and mud intrusions termed
Arab J Geosci
Fig. 5 Satellite images and field photographs showing mud volcanoes of the Ormara and Gwadar clusters and features present in the old mud volcano deposits; a satellite view of the Ormara cluster, b satellite view of the Gwadar cluster, c field photograph of the main mud volcano of the
Gwadar cluster, d photograph of the recurrently emerging Malan Island in the Arabian Sea near the coastal belt of Makran, e flat-lying mudstone succession containing profusion of comparatively resistant cylindrical chimney-shaped features sticking out of the soft mudstone, and f closeup view of the cylindrical chimney-shaped features cutting across the mudstone/siltstone horizons, hammer for scale
“ extrusive mud formation
”
(Hunting Survey Corporation,
1961 ). Our plots of the old mud volcano deposits on satellite
images (Fig.
1
), as well as the
“ extrusive mud formation
” of the Hunting Survey Corporation (
1961 ) indicate that they are
closely related with the MZAMV.
Offshore mud volcanoes
A number of offshore mud volcanoes have been reported on the shallow shelf and deeper parts of the Makran accretionary wedge (Sondhi
1947 ; Tabrez et al.
1999
; Delisle et al.
2002
;
Delisle
2004 ; Wiedicke et al.
2001 ). Some of these mud
volcanoes, occurring on the shallow shelf area, have been emerging recurrently as mud islands. Sondhi (
1947
) documented the emergence of three mud islands in the Arabian
Sea off the coast of Makran, which he linked with the big earthquake (magnitude 8.2) of November 1945. A typical example is the Malan Island (Figs.
1
and
5c ), which emerged
three times on the same locality since 1945. Its first emergence during November 1945 was in association with the big earthquake of November 1945, whereas its second emergence (on
15th March 1999) was seemingly without any association with an earthquake. The island, in its initial stage of emergence, was round-shaped and covered an area of up to 5.2 ha, however, being mainly composed of soft sediments, waves/ tides eroded the island in less than a year. The third emergence of the Malan Island occurred during November 2010.
The recurring emergence of mud islands indicates episodes of enhanced mud extrusion, which may be relevant with higher rates of compression and/or major (or minor) seismic events. The enhanced mud extrusion events of onshore mud volcanoes within the Makran coastal belt have been shown to be associated with the earthquakes (Sondhi
1947
; Hunting
Survey Corporation,
1961 ). Aerial photographs taken on 25
January 1946 of Chandragup-I and the Khandawari mud volcano show evidence of vigorous mud flow from both craters. Snead (
1964 ) mentioned enhanced activity of
Chandragup-I and -II in response to a small earthquake on
26 September 1956. He further reported that the clear water crater of the Chandragup-II was replaced by mud, the level of the fill rose by 2 ft, and mud extrusion was found to have
"splattered approximately 20 ft upon the side of the crater" and
„

Arab J Geosci

Arab J Geosci that the presently dormant, 30-m high, mud volcano of
Chandragup-III had erupted in the summer of 1959 and produced mudflows on its flank, which had dried-up during his visit in fall.
The island was composed of irregular mass of light greenish gray to very light gray mud breccias with very poorly sorted angular boulder- to cobble-size fragments of sandstone. It contained various circular vents, which episodically extruded thick mud slurry, violently in the initial stages, along with highly inflammable methane gas. We propose that the recurrently emerging Malan Island represents response of cyclic phases of enhanced mud extrusion, which in turn, are related with the compression and seismic events. The enhanced extrusion events are followed by periods of relative quiescence characterized by moderate activity and subsequent disappearance in response to erosion by waves/tides (Deville and
Guerlais
2009
). The plot of the occurrences of mud volcanoes on satellite image and geological map (Figs.
1
and
2
) indicates that the offshore mud volcanoes, including the Malan Island, are part of the MZAMV. The Malan Island (previously called
Hingol Island) is the lateral continuation of the Chandragup and
Khandawari clusters, which also line-up along the axis of the
Dhak Anticline with a thrust (Figs.
1 ,
2
, and
3
). The active mud volcanoes lay along the major fault zones (Vredenburg
1909 ;
Sondhi
1947 ). The previously reported four mud volcanoes of
the Chandragup-I, -II, -III, and -IV and Jebel-u-Ghurab cluster are associated with the axis of the Dhak Anticline, however, the remaining two subclusters of the North and West Chandragup line-up with another thrust north of the Dhak Anticline (Fig.
1 ;
Table
2 ). Plot of the mud volcanoes on the Landsat-5 TM
images indicates that mud volcanoes occur within a prominent zone, which we call the Makran zone of active mud volcanoes
(Fig.
1
). Our plot demonstrates that almost all clusters and subclusters of mud volcanoes line-up along the tectonic lineaments and define the ascend paths of the fluidized mud.
Apart from the offshore mud volcanoes that occur in the shallow marine part of the Makran coastal belt, Wiedicke et al.
( 2001 ) have mapped conical mounds of 1±1.5-km diameter
and up to 65-m height at the foot of the active Makran continental margin, which developed seaward of the accretionary front in a relatively planar zone, where the build-up of tectonic pressure initiates deformation. Wiedicke et al. (
2001 )
suggest that mud volcanism evolved at two main sites seaward of accretionary front of the Makran continental margin, where large conical mounds have been developed and currently appear to be inactive. These large mounds are accompanied by several small mounds; judging from the shallow seismic records, some of these may be very young. A nearby buried mound, approximately 460 ka old, suggests that the process of mud extrusion may not be ephemeral at this structural position of the accretionary margin; a careful survey should discover more features of this kind, active and fossil ones (Wiedicke et al.
2001
).
Conclusions
(1) The number of active mud volcanoes in the Makran accretionary wedge is much higher than those reported earlier. Using high-resolution satellite images, over 70 active mud volcanoes were recognized, plotted on mosaic of four Landsat TM images and described. Mud volcanoes occur in 14 clusters and subclusters.
(2)
The active mud volcanoes occur in a well-defined zone; we call it the MZAMV, which is parallel to the regional trend of the accretionary belt. The zone, as well as its component clusters and subclusters, generally line-up along thrusts related with the axes of the anticlines.
(3)
The MZAMV also includes the offshore mud volcanoes of the shallow shelf area, specifically the
“
Malan Island,
” that has periodically emerged and vanished three times since 1945 on the same locality. The phenomena has been going on during the geological past and anticipated to continue in the future. The Malan Island (previously called Hingol Island) is the lateral continuation of the
Chandragup and Khandawari clusters, which also lineup along the axis of the Dhak Anticline associated with a thrust. Several occurrences of very thick mud deposits are present within the MZAMV and further north, having trends parallel to the Makran accretionary wedge and display features that are characteristic of the old mud volcanoes, suggesting that mud volcanism has been an ongoing phenomena since Pliocene or even earlier.
(4)
The enhanced mud extrusion activity, i.e., violent extrusion of mud volcanoes and/or emergence of islands have relevance with seismic phenomena and, therefore, may be taken seriously.
(5)
The clusters/subclusters of mud volcanoes line-up along the thrusts and anticlinal axes, which defining the ascend paths of the fluidized mud.
Acknowledgments AMK is thankful to the J. William Fulbright Foreign Scholarship Board, Bureau of Educational and Cultural Affairs,
United States Department of State, and Council for International Exchange of Scholars for his selection for the Post-Doctoral Fellowship and cooperation throughout his stay during 2010
–
2011. Vice Chancellor,
University of Balochistan is acknowledged for approval of sabbatical leave for AMK.
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