structural elements of the makran region

8/3/2019 Structural Elements of the Makran Region

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O R I G I N A L P A P E R

Structural elements of the Makran region, Oman sea

and their potential relevance to tsunamigenisis

Mohammad Mokhtari Æ Iraj Abdollahie Fard Æ Khaled Hessami

Received: 2 September 2007 / Accepted: 15 December 2007 / Published online: 12 February 2008Ó Springer Science+Business Media B.V. 2008

Abstract The character of convergence along the Arabian–Iranian plate boundary

changes radically eastward from the Zagros ranges to the Makran region. This appears to

be due to collision of continental crust in the west, in contrast to subduction of oceanic

crust in the east. The Makran subduction zone with a length of about 900 km display

progressively older and highly deformed sedimentary units northward from the coast,

together with an increase in elevation of the ranges. North of the Makran ranges are large

subsiding basins, flanked to the north by active volcanoes. Based on 2D seismic reflectiondata obtained in this study, the main structural provinces and elements in the Gulf of Oman

include: (i) the structural elements on the northeastern part of the Arabian Plate and, (ii)

the Offshore Makran Accretionary Complex. Based on detailed analysis of these data on

the northeastern part of the Arabian Plate five structural provinces and elements—the

Musendam High, the Musendam Peneplain, the Musendam Slope, the Dibba Zone, and the

Abyssal Plain have been identified. Further, the Offshore Makran Accretionary Complex

shown is to consist Accretionary Prism and the For-Arc Basin, while the Accretionary

Prism has been subdivided into the Accretionary Wedge and the Accreted/Colored

Melange. Lastly, it is important to note that the Makran subduction zone lacks the trench.

The identification of these structural elements should help in better understanding the

seismicity of the Makran region in general and the subduction zone in particular. The 1945

magnitude 8.1 tsunamigenic earthquake of the Makran and some other historical events are

illustrative of the coastal region’s vulnerability to future tsunami in the area, and such data

should be of value to the developing Indian Ocean Tsunami Warning System.

Keywords Makran Á Tsunami wave heights Á Subduction zone Á Accretionary margin Á

Dibba Fault Zone Á Indian Ocean Á Seismic reflection

M. Mokhtari (&) Á K. Hessami

International Institute of Earthquake Engineering and Seismology, No. 26, Argavan Ave, Dibaji

Shomali, Tehran, Iran

e-mail: [email protected]

I. Abdollahie Fard

National Iranian Oil Company, Exploration Directorate, Tehran, Iran

123

Nat Hazards (2008) 47:185–199

DOI 10.1007/s11069-007-9208-0



1 Introduction

The Makran Accretionary Complex is bounded to the north by the Jaz Murian and Hamun

Mashkel depressions and to the south-east is marked by the base of the continental slope,

some 150 km offshore. To the south and west, the area is bounded by the narrow and steepcontinental margin of Oman (Fig. 1). The Makran Accretionary Complex is bounded to the

east and west by large transform faults of the Zendan-Minab Fault System and the Oranch

Fault Zone, respectively (Fig. 1).

Based on pervious and present studies (e.g., Farhoudi and Karig 1977; Platt et al. 1985)

the Makran region is composed of a large sedimentary prism accreted during the Cenozoic.

All the characteristics of Accretionary prisms with exception of the trench that have been

observed in other well-studied arcs can be identified or inferred in the Makran, which,

however, is unique in its degree of surface exposure.

For the first time, Stoneley (1974) proposed a subduction zone along the Makran coasts

that formed the boundary between the Arabian and Eurasian Plates. Later, Shearman

(1977) and Farhoudi and Karig (1977) presented data to support this hypothesis.

Fig. 1 Plate tectonic setting of the Oman Sea and the main structural elements, the plate boundaries in the

north of the Indian Ocean are also shown; AFP; African Plate, ARP; Arabian Plate, AS; Arabian Sea, COFS;

Chaman Oranch Fault System, CS; Caspian Sea, GA; Gulf of Aden, GO; Gulf of Oman, INO; Indian Ocean,

INP; Indian Plate, MAW; Makran Accretionary Wedge, OMFZ; Owen Murray Fault Zone, PG; Persian

Gulf, RS; Red Sea, ZSZ; Zagros Suture Zone

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Quittmeyer and Jacob (1979) conducted a comprehensive study of the Makran region

seismicity and concluded that it is consistent with the interpretation of this area as an active

subduction zone. In addition, Page et al. (1979) by performing a field survey of the Iranian

coastline, air photo analysis, and aerial reconnaissance, confirmed the tectonic model of

subduction zone for Makran coasts.The Makran region both onshore and offshore in contrast to its eastern and western ends

that cannot be classified with high seismic activity. However, due to its nature of being an

active subduction zone, the region historically has been affected by tsunamigenic earth-

quakes. The oldest record of tsunami in the region is from November 326 BC earthquake

near the Indus delta/Kutch region that set off massive sea waves in the Arabian Sea

(Lisitzin 1974). Tsunami has also been observed on the Iranian coast from a local earth-

quake between 1st April and 9th May 1008 (Murty and Bapat 1999). In addition, the 8.1

magnitude earthquake of 1945 created a significant tsunami in the region killing at least

4,000 people and having great economic impact in Pakistan, Oman, and Iran (Pacheco and

Sykes 1992, Pararas-Carayannis 2006). It led to the formation of four small islands. A large

volume of gas that erupted from one of the islands, sent flames leaping ‘‘hundreds of

meters’’ into the sky (Mathur 1988). The tsunami reached a height of 12 m in some Makran

ports (Pararas-Carayannis 2006). Recently, a comprehensive catalogue of tsunami occur-

rence in the Indian Ocean was presented by Rastogi and Jaiswal (2006) indicating the

susceptibility of the Makran and its vicinity to future tsunami. In this respect and in the

light of the area’s extensive development and high growth of population, inclusion of

Makran zone in the Indian Ocean Early Warning System has become a necessity.

In this study using seismic reflection data in defining the main structural provinces and

elements, the seismicity of the region has been elaborated.

2 Tectonic evolution of northern Indian Ocean

The Gulf of Oman is a remnant of Late Cretaceous/Early Paleocene oceanic crust. Figure 1

shows the major structural elements and the plate boundaries in the northern Indian Ocean.

The evolution of this region including the Oman Sea has been a long and complex process,

since initial rifting and ocean floor spreading of the Neo-Tethys in Late Permian time. The

oldest evidence of seafloor spreading is found in the Oman Mountains, where Permian

faunas are interbedded with basaltic pillow lavas, sills, dykes, and volcanics (EarlyPermian) (Glennie 2000). This first phase of spreading lasted till Late Triassic (Neo-Tethys

I). The width of the ocean had by then reached 400 km in the present Oman Sea (Glennie

2000). The spreading axis then jumped to the northeast. The oceanic crust documented

from the second phase (Neo-Tethys II) is of Upper Jurassic–Turonian age (McCall 1985;

Nicolas 1988).

In the Jurassic age, a thin continental sliver (the Bajgan–Dur–Kan Carbonate Fore-Arc)

was rifted off the continental margin of the Eurasian plate, and the Inner Makran Spreading

zone developed, with ophiolites ranging in age from Early Cretaceous to Early Paleocene

(McCall 1985). This rift has the character of back-arc spreading rather than a mid-oceanicspreading ridge.

In Albian–Aptian times (110 Ma) convergence between the African-Arabian and the

Eurasian Plate started. Two northward dipping subduction zones developed, nearly, at the

same time. A southern subduction zone developed about 800 km north of the present

continental margin of Oman. It started as a low angle northward intra-oceanic subduction

at a mid-ocean ridge (McCall 1985; Nicolas 1988) (Fig. 2). This has been documented by

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the high-temperature Cenomanian (90 Ma) metamorphism at the ophiolite sole (Hacker

1994). In the Campanian convergence along the margin of Oman changed character from

subduction to obduction.The northern subduction zone, located south of the Bajgan–Dur–Kan Carbonate Fore-

Arc, resulted in accretion of the Colored Melange (Fig. 2). Onset of subduction postdates

exotic blocks of Albian–Aptian reefal limestones in the melange, together with Late

Pliensbachian–Late Cretaceous ophiolites and deep marine sediments (McCall 1985). The

youngest sediments in the Colored Melange are Late Cretaceous-Early Paleocene shallow

marine bio-micrites, probably representing syn-tectonic deposition (McCall 1985).

During the Campanian (80 Ma), the southward migration of nappes reached the con-

tinental margin of Oman, resulting in down-flexing and obduction of oceanic crust onto the

Arabian Plate (Glennie et al. 1973; Lamphere 1981; Montigny et al. 1988). By the end of

the Cretaceous, obduction along the southern continental margin of the Neo-Tethys had

come to a halt. Since then the continental margin of Oman has been a passive margin, and

the remnant of the Neo-Tethyan oceanic crust has become a part of the African-Arabian

Plate. Subduction on the northern subduction zone continued and is still active off the coast

of Makran. The initial Accretionary front is located about 110 km north of the present

coastline and about 230 km north of the present Accretionary front.

Fig. 2 Schematic subduction history in the Oman Sea along the profile shown in the index figure at the left

corner. AP, Arabian Plate, BDKZ, Bagjan Dur-Kan Zone; CM, Colored Melange; EF, Eocene Flysch; MS,

Molassic Sediments; OSZ, Oman Subduction Zone, SO; Semail Ophiolite, and AW; Accretionary Wedge

(modified after McCall 1985)

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The onset of convergence of the Neo-Tethys approximately coincides with the opening

of the Atlantic, and might have been triggered by increased rotational speed of the African-

Arabian Plate. The change from an active to a passive margin coincides with the shift in

spreading axis in the Indian Ocean, leaving the Seychelles on the African Plate (Glennie

et al. 1973; Lamphere 1981).The break off of the Arabian Plate from the African Plate probably resulted in an

increase in subduction rate. At this stage the mountain chains along the Himalayan con-

tinent–continent collision zone were uplifted and eroded, resulting in a major increase in

sediment input into the Indian Ocean and the Oman Sea. The formation of the Makran

Fore-Arc Basins was also probably controlled by the increased subduction rate in com-

bination with increased sediment input behind the Accretionary front.

The Makran coastline, once much further north has been regressing ocean-ward at a rate

of about 1 cm per year at least since the Early Miocene due to tectonic activity (White and

Louden 1982). Consequently, two-thirds of the Accretionary prism is located onshore. The

recent sediments deposited offshore are therefore expected to be more proximal than the

older distal-deep marine sediments.

These structural features have all been determined based on evidence from the surface

geology, but in the following section, the main structural elements we observe based on

geophysical data will be discussed. The purpose is to define possible sources for seismicity

in the offshore region as the site of future earthquake and tsunami.

3 Main structural elements

Based on the present study, utilizing 2D seismic reflection data the main structural

provinces and elements in the Gulf of Oman are (i) the structural elements on the north-

eastern part of the Arabian Plate and (ii) the Offshore Makran Accretionary Complex

Elements. On the northeastern part of the Arabian Plate, five structural provinces and

elements have been defined (Fig. 3): the Musendam High, the Musendam Peneplain, the

Musendam Slope, the Dibba Zone, and the Abyssal Plain. The Zendan-Minab Fault System

and the Accretionary front define the western and southern boundary of the Makran

Accretionary Complex, respectively. The Oranch Fault Zone (Fig. 1) is located in the

eastern side of this complex and is considered as the western boundary of the Indian Plate,

while the Murray ridge system defines the offshore boundary of the Arabian and Indianplates.

These seismic profiles gathered under auspices of National Iranian Oil Company in

2000 using conventional marine 2D seismic methodology. These are part of PC2000

project which covers both the Persian Gulf and Oman Sea.

The Offshore Makran Accretionary Complex consists of Accretionary Prism and the

For-Arc Basin. The Accretionary Prism has been subdivided into the Accretionary Wedge

and the Accreted/Colored Melange (Fig. 3).

3.1 The structural elements of the northeastern part of the Arabian Plate

The structural elements of the northeastern part of the Arabian Plate include: (i) the

Musendam High which defines the northern offshore extension of the Musendam Penin-

sula; (ii) the Dibba Fault Zone as a prominent structural feature/lineament cutting across

the Musendam Peninsula in a southwest/northeast direction (Fig. 4); (iii) the Musendam

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Peneplain located on the west of the Zendan-Minab Fault System (Fig. 4) which was

subject to extensive erosion in the Early Tertiary resulting in a very mature peneplain; (iv)

the Musendam Slope which lies to the southeast of the Musendam Peneplain, up against

the Zendan-Minab Fault System and might represent the Neo-Tethyan paleo-slope, which

implies that the crust underlying the slope is an attenuated continental crust, not oceanic;

and (v) the Abyssal Plain which represents un-deformed remnant of the Neo-Tethyan

oceanic crust, now part of the Arabian Plate with a cover of deep marine sediments

(Fig. 3). Total thickness of the sediments in the Abyssal Plain is about 7.5 km and

are found all over the Oman Sea. Figure 5 shows the seismic expression of the Abyssal

Plain.

3.2 The plate boundaries

The Plate Boundaries in the Makran region are (i) The Zendan-Minab Fault System that

represents the eastern boundary of the Arabian Plate (Fig. 1), (ii) the Oranch Fault Zone

which is part of the Eurasian–Indian plate boundary complex (Fig. 1) and (iii) the NE–SW

trending Murray Ridge System in the northern Arabian Sea extends about 750 km (Fig. 1).

Onshore the Zendan-Minab Fault System is defined by a series of sub-parallel north–

south trending right-lateral (dextral) transpressional faults, creating a series of en-echelon

oriented compressional structures. Based on a teleseismic study by Yamini-Fard et al.

(2007), the convergence between the Arabian plate and Central Iran may be accommo-

dated by a mechanism of distributed deformation at depth. These seismological evidences

suggest that the transition from the Zagros collision zone to the Makran subduction zone is

not abrupt. However, GPS measurements suggest that the Zendan-Minab Fault System is

Fig. 3 Main structural element of the Makran margin based on interpretation of seismic profiles (in the

Iranian side)

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an active fault at the present (Bayer et al. 2006). A zone of decollement can be considered

as a result of the first stage of the continental collision in this region as proposed by White

and Ross (1979) and reported by Byrne et al. (1992).

The Oranch Fault Zone has evolved from a thrust fault of the Arabian–Eurasian col-

lisional complex to a strike-slip fault along the Eurasian–Indian transform boundary. The

Arabian–Eurasian plate boundary, a subduction zone, is beneath the Indian Ocean to the

south of the Makran region (Fig. 6).

The Murray Ridge System is divided into basins and ridges. This has been interpreted as

a transform margin of the Indian Plate that has been active since the Upper Cretaceous.

Seismic reflection profiles from the Murray Ridge in the Gulf of Oman, show a significant

component of extension across the predominantly strike-slip Indian–Arabian plate boundary(Fig. 7). The Murray Ridge lies along the northern section of the plate boundary, where its

trend becomes more easterly and thus allows a component of extension. The Dalrymple

Trough is a 25 km wide, steep-sided half-graben, bounded by large faults with components

of both strike-slip and normal motion. The throw at the seabed of the main fault on the

south-eastern side of the half-graben reaches 1,800 m (Edwards et al. 2000).

Fig. 4 Satellite image showing the location of Zendan-Minab Fault System and Dibba Fault Zone as major

structural elements in the western part of the Makran Accretionary Complex

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Fig. 5 2D offshore seismic profile showing the boundary between the abyssal plain and the Makran

Accretionary Complex. Note the lack of a trench in front of the Accretionary Complex. The line is located in

the Iranian water (location of the seismic section shown on the index map in the bottom left corner) (Curtsey

of National Iranian Oil Company)

Fig. 6 Seismic section across offshore extension of the Zendan-Minab Fault System (location of the

seismic section shown on the index map in the bottom left corner) (Curtsey of National Iranian Oil

Company)

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3.3 The Offshore Makran Accretionary Complex Elements

The Accretionary Complex consists of the Accretionary Wedge and the Accreted/ColoredMelange. The distinction between the two provinces is based on differences in both

structural style and driving mechanisms for structuring. Figure 5 shows the seismic

expression of the Makran Accretionary Complex. Note the continuous steepening of thrust

planes away from the Abyssal Plain. Sedimentary basins between fold/thrust ridges are

filled with continental derived sediments.

3.3.1 The Accretionary Wedge

The Accretionary Wedge represents the initial stages in the Accretionary process, to astage when primary sedimentary features and individual thrusts can no longer be identified.

The only driving force is the continuous subduction along a decollement about 2.5 km

below the seabed in the Abyssal Plain. The overall structural geometry created is a series of

stacked imbricate slices of off-scraped sediments, separated by northward facing thrusts

planes (Figs. 5, 8).

3.3.2 The Accreted/Colored Me lange

The Accreted/Colored Melange is an irregular zone with very complex structure, where

nearly no primary sedimentary structures are preserved (Fig. 5). In general, the Accreted/

Colored Melange has a diapiric character along the whole Accretionary Complex. The

contact between the Accreted/Colored Melange and the Accretionary Wedge to the south is

clearly tectonic. In general the Accreted/Colored Melange appears to be under-thrusted and

uplifted by the Accretionary Wedge. To the north the contact between the Accreted

Fig. 7 Seismic section across the Eastern Murray Ridge (location of the seismic section shown on the index

map in the bottom left corner) (Curtsey of BGR, Hanover, Germany)

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Melange and the Fore-Arc Basin shows a continuous onlap of the Fore-Arc Basin sedi-ments onto the Accreted/Colored Melange. Post-depositional faulting or diapirism often

obscures the primary sedimentary contact.

3.3.3 Fore-Arc Basin

The Fore-Arc Basin is not a continuous basin running along the full length of the Makran

Accretionary Complex. The Fore-Arc Basin was initiated, as a series of narrow half

grabens controlled by seaward facing listric normal faults, with sediments onlapping the

rising diapirs of the Accreted Melange to the south (Fig. 5). Through time the sub-basins

expanded southward. In places two sequences can be identified in the fore-arc basin

(Fig. 9), a deep strongly deformed thrusted and mobilized sequence and an upper sequence

dominated by normal faulting.

4 Review of tsunami sources in the Makran Accretionary Complex

Based on the above-mentioned geological setting, tectonic evolution and main structural

elements, we classify the Makran Accretionary Complex as a major seismically active

zone. Moreover, in a plate tectonic setting like that of the Makran Accretionary Complex a

fairly high rate of earthquake activity would be expected, as in many of the other major

Accretionary complexes/subduction zones around the world (e.g. Agean region). However,

this region which is located between the Zendan-Minab Fault System and Oranch Fault

Zone shows relatively low seismicity (based on available data in the region, see Fig. 10) in

comparison with the surrounding region.

Fig. 8 NNE–SSW seismic line through the Accretionary Wedge. Note the continuous steepening of thrust

planes away from the Abyssal Plain. Sedimentary basins between fold/thrust ridges are filled with

continental derived sediments (location of the seismic section shown on the index map in the bottom right

corner) (Curtsey of National Iranian Oil Company)

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It is important to note that in spite of low seismicity some historical data about tsunamis

in the Makran region have been reported by Murty and Rafiq ( 1991), Murty and Bapat

(1999), Dominey-Howes et al. (2007), Rastogi and Jaiswal (2006). This could be related to

very long recurrence interval of large magnitude tusnamigenic earthquakes, which is not

recorded in the available historical data. According to above mentioned reports, the total

number of tsunami events in the Makran zones is three which includes two of seismic

origin and one of unknown origin. The most recent event is the major earthquake generated

tsunami of 1945 in the eastern Makran which was an inter-plate thrust event that ruptured

approximately one-fifth of the length of the subduction zone (Fig. 10). It is important to

note that the epicenter of this event is also close to the Sonne Fault which has createdsegments on the Makran Subduction Zone. The crossing points between the Makran

Subduction Zone and these oblique fault zones suggest to us that this junction can be a

location for occurrence of major earthquake activities. However, more studies are required

for further clarification.

In addition to the above, Byrne et al. (1992) reported nine smaller events in eastern

Makran that are also located at or close to the plate interface and have thrust mechanisms

similar to that of the 1945 shock. Seaward of these thrust earthquakes lies the shallowest

70–80 km of the plate boundary. This segment and the overlying Accretionary Wedge

remain aseismic both during and among great earthquakes.

As in other subduction zones, this aseismic zone lies within that part of the Accretionary

Wedge that consists of largely unconsolidated sediments (P wave seismic velocities less

than 4.0 km/s). The existence of thrust earthquakes indicates that either the sediments

along the plate boundary in the eastern Makran become sufficiently well consolidated and

dewatered at about 70 km from the deformation front, or lithified rocks are present within

the Fore-Arc Basin so that stick-slip sliding behavior becomes possible. Byrne et al. (1992)

Fig. 9 North–south seismic lines through western part of the Fore-Arc Basin. Basin growth is controlled by

syn-depositional listric faulting and continuous growth of diapir. Shortening has been occurred by

continuous tilting/rotation of graben sediments (location of the seismic section shown on the index map in

the bottom right corner) (Curtsey of National Iranian Oil Company)

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showed that a large quantity of unconsolidated sediment does not necessarily indicate a

low potential for great thrust earthquakes. In contrast to the east, the plate boundary in the

western Makran has no clear record of historically great events, nor has modern instru-

mentation detected any shallow thrust events for at least the past 25 years. Most

earthquakes in the western Makran occur within the down-going plate at intermediate

depths (Byrne et al. 1992; Kukowski et al. 2000). The large changes in seismicity between

the eastern and western Makran suggest segmentation of the subduction zone. This is alsosupported by Kukowski et al. (2000) where they introduce a new boundary coinciding very

well with the Sonne strike-slip fault (Fig. 10). The western part is characterized by the

absence of inter-plate events. East of the Sonne fault and west of long 64°E is the only

region with a clustering of events within the submarine and southernmost onshore part of

the Accretionary Wedge, also including the Mw 8.1 event of 1945 (Byrne et al. 1992)

(Fig. 10). Most events in the wedge appear to be pure-thrust earthquakes and are inter-

preted as plate boundary events (Quittmeyer and Kafka 1984; Byrne et al. 1992). The

earthquake of August 12, 1963, a few tens of kilometers east of the Sonne fault, had a large

strike-slip component and its depth was estimated to be only 5 km (Quittmeyer and Kafka

1984). Taking into account the uncertainties of focal estimation, it is suspected that this

event may have occurred in connection with motion along the Sonne fault (Kukowski et al.

2000). The subduction rate based on GPS measurements indicated by Vernant et al. (2004)

is about 18 mm/year.

The absence of plate boundary events in the western Makran indicates either that

entirely aseismic subduction occurs or that the plate boundary is currently locked and

Fig. 10 The seismicity map of Makran Region; star sign shows the 1945 Tsunamigenic earthquake

location. Regional tectonic map of Arabian–Indian–Eurasian convergence zone showing the Sonne Fault

and distribution of earthquakes (circles; compiled from Byrne et al. 1992; Jackson et al. 1995; and U.S.

National Earthquake Information Center data set). Onshore topography is from satellite altimetry; submarine

topography is combined from satellite altimetry and RV Sonne cruise data set (modified after Kukowskiet al. 2000)

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experiences great earthquakes with long repeat times. Evidence is presently inconclusive

concerning which of these two hypotheses (or some other) is the correct one.

As mentioned above, the largest recorded earthquake (tsunamigenic) occurred at 21:56

UTC on 28th November 1945 with epicenter of 87.1 km SSW Churi (Baluchistan),

Pakistan. It was located at 24.50 N and 63.00 E with a magnitude of Mw 8.1 (Fig. 10).Another earthquake at 1424 UTC located at 25.10 N, 63.40 E on the 5th August 1947

also occurred off the Makran coast (Baluchistan), Pakistan. There is no report of tsunami

generation associated with this event, which has occurred in a very shallow depth of the

coast.

This was the last major tsunami-generating earthquake in the Oman Sea. More than

4,000 people were killed on the Makran coast by both the earthquake and the tsunami. The

tsunami reached a run-up height of approximately 12 m in some Makran ports (Pararas-

Carayannis 2006) and caused great damage to the entire coastal region. The towns of Pasni

and Ormara were badly affected. Both were reportedly ‘‘underwater’’ after the tsunami.

The tsunami was also recorded at Muscat and Gwadar (Pararas-Carayannis 2006).

The waves were about 2 m high in Karachi (Pararas-Carayannis 2006). The first wave

was recorded at 5:30 am, then at 7:00 am, 7:15 am and finally at 8:15 am. The last

wave at 8:15 was the biggest. The tsunami had a run-up height of 11.0–11.5 m in Kutch,

Gujarat. At 8:15 am, it was observed on Salsette Island, i.e., Mumbai. It was recorded in

Bombay Harbour, Versova (Andheri), Haji Ali (Mahalaxmi), Juhu (Ville Parle), and Danda

(Khar).

5 Conclusions

Different from most other Accretionary Complexes based on the 2D seismic reflection data

there is no trench developed in front of the Makran Accretionary Complex. The absence of

trench in this region can be due to the fact that the subduction angle at the accretionary

front is very low; it is due to existence of thick sediments with low compaction or it might

be caused by high deposition rate. However the main reason is most probably the low angle

of subduction.

The presence of well-defined late Holocene marine terraces along portions of the

coasts of eastern and western Makran could be interpreted as evidence that both sections

of the subduction zone are capable of generating large plate boundary tsunamigenicearthquakes. The occurrence of tsunamigenic earthquake in the eastern segment has been

documented, but well defined large earthquakes in the west so far is lacking. This could

either be that the western Makran is capable of producing great earthquakes or it could

rupture as a number of segments in somewhat smaller-magnitude events. Alternatively, it

is possible that western Makran is significantly different from eastern Makran and

experiences largely aseismic slip at all times. Knowledge of the velocity structure and

nature of the state of consolidation or lithification of rocks at depth in the interior portion

of the fore-arc of western Makran should help to ascertain whether that portion of the

plate boundary moves aseismically or ruptures in large to great earthquakes. A resolutionof this question has important implications for seismic hazard assessment of the western

Makran.

Based on the above the potential of tsunamigenic earthquake occurrence necessitate an

improved understanding of the seismotectonic and seismicity of the Makran region, a

better understanding of past earthquake sources through the use of paleotsunami, tsunami

hazard assessment, preparation of evacuation maps and hazard reduction strategy.

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Acknowledgments The authors would like to thank National Iranian Oil Company, Exploration Direc-

torate for providing the seismic sections and permission for their publication. The authors would also like to

thank the two anonymous reviewers for their constructive comments and suggestions to improve the

manuscript.

References

Bayer R, Chery J, Tatar M, Vernant P, Abbassi M, Masson F, Nilforoushan F, Doerflinger E, Regard V,

Bellier O (2006) Active deformation in Zagros–Makran transition zone inferred from GPS measure-

ments. Geophys J Int 165:373–381

Byrne DE, Sykes LR, Davis DM (1992) Great thrust earthquakes and aseismic slip along the plate boundary

of the Makran subduction zone. J Geophys Res 97(B1):449–478

Dominey-Howes D, Cummins P, Burbidge D (2007) Historic records of teletsunami in the Indian Ocean and

insights from numerical modelling. Nat Hazards 42(1):1–17

Edwards RA, Minshull TA, White RS (2000) Extension across the Indian Arabian plate boundary: the

Murray Ridge. Geophys J Int 142:461–477Farhoudi G, Karig DE (1977) The Makran of Iran and Pakistan as an Active Arc System. Abstr., EOS

Trans., Am Geophys Union 58:446

Glennie KW (2000) Cretaceous tectonic evolution of Arabia’s eastern plate margin: a tale of two oceans.

SEPM special publication 69, pp 9–20

Glennie KW, Boeuf MGA, Hughes Clarke MW, Moody-Stuart M, Pilaar WFH, Reinhardt BM (1973) Late

Cretaceous nappes in Oman Mountains and their geologic evolution. AAPG Bull 57:5–27

Hacker BR (1994) Rapid emplacement of young oceanic lithosphere: argon geochronology of the Oman

ophiolite. Science 265:1563–1565

Jackson J, Haines J, Holt W (1995) The accommodation of Arabia-Eurasia plate convergence in Iran.

J Geophys Res 100:15205–15219

Kukowski N, Schillhorn T, Flueh ER, Huhn K (2000) Newly identified strike-slip plate boundary in the

northeastern Arabian Sea. Geology 28(4):355–358Lamphere MA (1981) K-Ar ages of metamorphic rocks at the base of the Semail Ophiolites, Oman.

J Geophys Res 86:2777–2782

Lisitzin E (1974) Sea level changes. Elsevier oceanographic series, vol 8, New York, p 273

Mathur SM (1988) Physical geology of India. National Book Trust of India, New Delhi

McCall GJH (ed) (1985) Area report, East Iran project, area no: 1 (North Makran and South Beluchistan),

Geological Survey of Iran

Montigny R, Le Mer O, Thuizat R, Whitechurch H (1988) K-Ar and 40Ar/ 39Ar study of metamorphic rocks

associated with Oman ophiolite: Tectonic implications. Tectonophysics 151:345–362

Murty TS, Rafiq M (1991) A tentative list of tsunamis in the marginal seas of the north Indian Ocean.

Nat Hazards 4(1):81–84

Murty TS, Bapat A (1999) Tsunamis on the coastlines of India. Sci Tsunami Hazards 17(3):167–172

Nicolas A (1988) Structures of ophiolites and dynamics of oceanic lithosphere. Petrology and structural

geology 4. Kluwer, Dordrecht

Pacheco J, Sykes L (1992) Seismic moment catalog of large shallow earthquakes, 1900 to 1989. Bull

Seismol Soc Am 82:1306–1349

Page WD, Alt JN, Cluff LS, Plafker G (1979) Evidence for the recurrence of large-magnitude earthquakes

along the Makran Coast of Iran and Pakistan. Tectonophysics 52:533–547

Pararas-Carayannis G (2006) The potential of tsunami generation along the Makran Subduction Zone in the

northern Arabian Sea. Case study: the earthquake and Tsunami of November 28, 1945. Sci Tsunami

Hazards 24(5):358–384

Platt JP, Leggett JK, Young J, Raza H, Alam S (1985) Large-scale sediment underplating in the Makran

accretionary prism, southwest Pakistan. Geology 13:507–511

Quittmeyer RC, Jacob KH (1979) Historical and modem seismicity of Pakistan, Afghanistan, Northwestern

India, and Southeastern Iran. Bull Seismol Soc Am 69(3):773–823

Quittmeyer VN, Kafka AL (1984) Constraints on plate motions in southern Pakistan and northern Arabian

Sea from focal mechanisms of small earthquakes. J Geophys Res 89:2444–2458

Rastogi BK, Jaiswal RK (2006) A catalog of tsunamis in the Indian Ocean. Sci Tsunami Hazards 25(3):

128–143

Shearman DJ (1977) The geological evolution of Southern Iran, the report of the Iranian Makran expedition.

Geogr J 142:393–410

198 Nat Hazards (2008) 47:185–199

123



Stoneley R (1974) Evolution of the continental margins bounding a former Tethys. In: Burk CA, Drake CL

(eds) The geology of continental margins. Springer, New York, pp 889–903

Vernant P, Nilforoushan F, Hatzfeld D, Abbasi MR, Vigny C, Masson F, Nankali H, Martinod J, Ashtiani A

(2004) Present-day crustal deformation and plate kinematics in Middle East constrained by GPS

measurements in Iran and northern Oman. Geophys J Int 157:381–398

White RS, Louden KE (1982) The Makran continental margin: structure of a thickly sedimented convergentplate boundary. In: Watkins JS, Drake CL (eds) Studies in continental margin geology, vol 34.

Mem Am Assoc Petrol Geol, pp 499–518

White RS, Ross DA (1979) Tectonics of the Western Gulf of Oman. J Geophys Res 84:3479–3489

Yamini-Fard F, Hatzfeld D, Farahbod AM, Paul A, Mokhtari M (2007) The diffuse transition between the

Zagros continental collision and the Makran oceanic subduction (Iran): microearthquake seismicity

and crustal structure. Geophys J Int 170:182–194

Nat Hazards (2008) 47:185–199 199

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