Monitoring the Variations of b-Value and Seismicity in the Makran Ranges, the Absence of a Notable Event in West of Makran Subduction Zone

Geodynamics Research International Bulletin (GRIB), Vol. (II) No. 02, SN:06, Summer 2014 All rights reserved for GRIB

XXXIX


Monitoring the Variations of b-Value and Seismicity in the Makran

Ranges, the Absence of a Notable Event in West of Makran

Subduction Zone

Jamileh Vasheghani Farahani

Institute of Geophysics, University of Tehran, Tehran, Iran

Email: [email protected]

Article History: Received: May. 11, 2014 Reviewed: May. 19, 2014 Revised: Jul. 22, 2014 Accepted: Aug. 15, 2014 Published: Sep. 16, 2014

ABSTRACT

The Makran subduction zone (MSZ) is situated in the south-eastern coast of Iran. Previous studies on historical earthquakes of Makran subduction zone indicate that the eastern part of the zone is more active compared to the western part. The important instrumental earthquake in this region was an earthquake which occurred on 16 April, 2013 with a magnitude of Mw=7.8 (USGS) in Sistan and Baluchestan province (north-west of Saravan). In the western part, we had just a historical earthquake which occurred in 1483. The region in this study is limited to 56-63 E and 25-29N. In the western part of this region, an earthquake occurred recently with a magnitude of Mw=6.2 in Hormozgan province. We examined variations of b-values with time as a method that have b-values a precursory potential or not. It is suggested that b-value studies may be useful for estimating seismic gap or aseismic area in some regions and prediction of earthquake. It is believed that areas with low b-values may show asperities and for high b-values in the areas forecast creeping. Therefore, it is suggested that this idea must be investigated in different areas.

Keywords: Makran Subduction Zone (MSZ), B-Value, Earthquake Prediction, Saravan, Sistan and Baluchistan, Iran

1. INTRODUCTION

A useful parameter in seismology studies is the b-

value. In this research, it was tried to investigate the

b-value distributions for recent earthquakes in Sistan

and Baluchestan and Hormozgan provinces with

magnitude greater than 6.0. The Mw=7.8 (USGS)

earthquake occurred at 10:44:17 UTC (local time:

15:14:17) on 16 April, 2013 in NW of Saravan

region, SE Iran, approximately 82 km beneath the

Earths surface. Moreover, another important event in the region occurred on May 11, 2013, with

Mw=6.2.

The b-value is calculated from the magnitude-

frequency distribution (FMD) relation. The b-value

relation is shown by Gutenberg-Richter law in 1954:

(1) Log N a bM=

where N is the cumulative number of earthquakes, a

and b are constants. The slope of the FMD

distribution is the b-value. The a-value indicates

seismicity in region and b-value depends on the

stress regime and tectonic character of the region

(Allen et al., 1965; Mogi, 1967; Scholz, 1968;

Hatzidimitriou et al., 1985; Tsapanos, 1990). Bufe,

1970 and Gibowicz, 1973 believed that variations of

b-value were inversely related to the variations in the

stress level. In 1981, Kanamori stated that the stress

is high in areas with smaller b-value. Therefore,

decreasing b in the examined region may show increasing stress level before mainshocks.

Moreover, b-value in equation (1) can be obtained by

methods such as linear least squares regression or

maximum-likelihood using the equation (Aki, 1965;

Ustu, 1965; Bender, 1983):

(2)

min

logb eM M

=

1

where M denotes the mean magnitude and minM the

minimum magnitude of the given sample. The

assessment of minM is related to the magnitude

distribution (Equ. 1). The minimum magnitude can

be determined by plotting the cumulative number of

events as a function of magnitude (Fig. 1). The

magnitude of completeness, cM , is corrected by

/ 2M to compensate for the bias of rounding

magnitude to the nearest M bin (Nuannin, 2006).

Vol. (2), No. 03, SN:06, Summer 2014 3rd Article- P. XXXIX to XLVII

Available online at: www.geo-dynamica.com

GRIB Geodynamics Research International Bulletin

ISSN 2345 - 4997


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2. MATERIALS AND METHODS

2. 1.TECTONIC SETTINGS

Earthquake in Apr. 16, 2013 (Mw=7.8) occurred as a

result of normal faulting. The convergence between

the Eurasian and Arabian plates has resulted in nearly

1,000-km-long Makran subduction zone. This region

was divided into eastern and western parts by Byrne

et al. in 1992. The western and eastern parts of the

Makran in Iran are limited to Minab and Ornach- Nal faults. The borders of the Makran area are all rather

complex tectonic features. Major transpressional

strike slip systems, the Ornach- Nal and Chaman

fault zones shape the eastern part of Makran and

adapt the motion between the Eurasian plate and the

western part of the Indian plate (Byrne et al., 1992).

Kopp et al. in 2000 believed that Makran is one of

the largest accretionary wedges on Earth, and is

characterized by a reportedly high sediment thickness

of about 7 km.

The sedimentary hanging wall of the main dcollement is folded and imbricated in the modern

accretionary prism (e.g. White and Louden, 1982;

EllouzZimmermann et al., 2007b; Grando and

McClay, 2007; Haghipour, 2013). Szeliga et al.

(2012) have stated that the only available

geodetically measured inter-seismic velocities in the

region propose that in addition to slip on the Ornach

Nal fault, 1 cm/yr of strike-slip motion must be

accounted for in the direction parallel to the 2013

rupture trace, while 0.5 cm/yr of convergence builds

up in the fault normal direction (Jolivet et al., 2013). It has been checked that convergence rate is different

between eastern and western Makran. It is about 3-7

mm/yr higher rate in eastern Makran (Gripp and

Gordon, (1990); Argus and Gordon, (1991); DeMets

et al., (1994); McClusky et al., (2000); Drewes

(1998); Drewes and Angermann (2001); Gripp and

Gordon (2002); Sella et al., (2002); Kreemer et al.

(2003); McClusky et al. (2003); Prawirodirdjo and

Bock (2004); Vernant et al. (2004); Reilinger et al.,

(2006); Drewes (2009); DeMets et al. (2010); Argus

et al., (2010). Moreover, DeMets et al. (2010)

showed that the results using space geodesy are 5-15

mm/yr smaller than geologic results. Vernant et al.,

(2004) researches by GPS data suggested that Arabia

converges toward southern Iran at velocity of 23

2mm/yr near the western termination of the Makran

subduction, less than the time averaged velocity of

36.5 mm/yr based on the NUVEL 1 model (DeMets

et al., 1990). GPS data displays an eastward increase

in convergence rate, from 11 2 mm/yr at Jask to 19

2 mm/yr at Chabahar (Vernant et al., 2004). Other researches by Bayer et al. (2006); Apel et al., (2006)

confirm the greater convergence rate at eastern part

(located in Chabahar) compared with western part

(located in Jask). Recent GPS data show an increase

easterly in plate convergence rates (Rajendran et al.,

2012).

2. 2. SEISMICITY

The main event along the Makran Coast occurred in

1945 (Mw=8.1). Saravan earthquake (Mw=7.8)

occurred in the eastern end of Makran (Fig. 1), and it

had 41 victims (40 people in Pakistan and one person

in Iran) and more than 180 injuries. Tremors were

felt across Pakistan, north-western India and in the

Persian Gulf region.

Moreover, some moderate and large earthquakes

occurred in Saravan, including: M= 6.7 on April 18,

1983; M=6.9; June 13, 1934; M=5.5 and January, 14

2003. Fig. (2) shows the location of these

earthquakes around the Saravan Earthquake location

(Mw=7.8).

Fig. 1. Seismicity map of the mainshock area recorded by BIN and IRSC Networks.


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Another important event which recently occurred in

the Makran zone was Goharan earthquake (Mw=6.2)

in SE Iran on May 11, 2013 (Figs. 1 and 3). This

event was around the Minab- Zendan fault zone. Fig.

(3) shows the aftershock sequences (until March

2014). Besides, this earthquake had two foreshocks

with magnitudes M=4.7 and M=3.5 which occurred

on 9 May 2013. These events before mainshock were

very helpful in the region. Zare et al. (2013) reported

that the foreshock on May 9, 2013 produced a

preliminary alert at midday. This event led to

evacuation of the residents and then, they moved to

the local tents named Kapar. As a result, the death

toll was limited to one person in Irar village in

Goharan, SE Iran.

Fig. 2. Seismicity map of limited to the region of Saravan and some important earthquakes in the region.

Fig. 3. Seismicity and aftershocks map in region of Goharan (SE Iran, earthquake of 11 May 2013, Mw6.2)


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2.3. FREQUENCY MAGNITUDE

DISTRIBUTION FOR THE REGION

There are different ways to calculate the b-values.

The maximum likelihood method is the most

common way that was also used by Aki, 1965.

Fig. (4) shows the G-R relationship and the

magnitude of completeness, cM , for data in Saravan

region before main shock (from 1900 to before April

16, 2013). This Figure is an example for showing

some information for a and b-value and cM .

Fig. 4. a) Frequency-magnitude distribution of data before Saravan earthquake (left panel) and b) aftershocks (right panel) of the main-shock

(April 16, 2013) recorded by BIN and IRSC.

The results of the frequency-magnitude distributions

are presented in Figs. 4 (a, b) and shows that the b-

values are significantly different. Differences

between data before occurrence of the main shock

and after it confirm that the lower values of b

correspond well with those of the area under

increased stress. The b-value distribution for the

aftershocks of Saravan earthquake shows significant

changes in the area. It was observed that the b-value

increased significantly, from 0.746 for the data

before main shock to 1.06 after the main shock in the

region.

Fig. (5) depicts Frequency-magnitude distribution of

data before Goharan earthquake (main shock, Mw=

6.2) using just BIN catalog.

Fig. 5. a) Frequency-magnitude distribution of data before Goharan earthquake (left panel) and b) aftershocks (right panel) of the mainshock

(May 11, 2013) recorded by BIN from 1990 to May 11, 2013.

Fig. (6) is another example of FMD for Goharan

region by both catalogs from Broadband Iranian Network (BIN) and Iranian Seismological Center

(IRSC). The slope of red line corresponds to the b-

value. We tried to merge both Networks for

improving the quality of earthquake catalogs that

helped us to increase the accuracy of b-value investigation. Therefore, it was found that the

reliability of our research improves with our data and

it increases the reliability of the resulting b-values

2.5 3 3.5 4 4.5 5 5.5 6 6.5 7

100

101

102

Magnitude

Cumulative Number

Mc

b-value = 0.746 +/- 0.1, a value = 5.04a value (annual) = 3.11

Magnitude of Completeness = 4.7

2.5 3 3.5 4 4.5 5 5.5 6

100

101

Magnitude

Cumulative Number

Mc



2.5 3 3.5 4 4.5 5 5.5 6

100

101

102

Magnitude

Cumulative Number

Mc

b-value = 0.572 +/- 0.03, a value = 4.07,a value (annual) = 2.71


3 3.5 4 4.5 5 5.5 6

100

101

102

Magnitude

Cumulative Number

Mc



a b


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and hazard mitigation. The Figures show that the b-

values in these two areas (east and west of the study

area) are different. Therefore, variations in b for two

areas were attributed to differences in stress and

material heterogeneity. These differences can be of

great importance for evaluation of the threat of

earthquake in the region.

Fig. 6. a) Frequency-magnitude distribution of data before mainshock, Mw=6.2 (left panel) and b) after mainshock (right panel) by merging data

(BIN and IRSC), respectively.

2. 4. VARIATIONS OF B-VALUE WITH TIME

Monitoring of b-value changes is essential for

understanding the earthquake hazard mitigation. This

study concentrates on the determination of the b-

value as a function of time for earthquakes in the

Makran ranges. The present study examined this

method as an earthquake precursor for hazard

assessment. It was also tried to investigate its potential as a method in a limited area for showing

temporal variations of b-values before large events.

Urbancic et al., 1992 and Wyss, 1973 believed that

an increase in effective stress results in a decrease in

b-value. Monitoring temporal changes in b-value for

different lengths of time such as short, medium or

long is a very important method for prediction of

hazards in the areas.

Sammonds et al. (1992) studied temporal b-value

variations. Their results showed that large

earthquakes often came before a medium-term

increase in b and then followed by a reduction in the

weeks-months before the main shock.

The earthquake on April 16, 2013 in NW Saravan

was investigated in this study and variations of b-

value with time were investigated. The data in Fig.

(7) shows the test for understanding variations of b-

value with time.

A sliding time-window containing 70 events was

used for the data in the BIN and IRSC catalog.

Selecting the number of records in the window is a

compromise between the time resolution and

smoothing effect of broad windows (Nuannin et al., 2005). The number of records in the window such as

50, 75, 150 and 200 were tested. Moreover, the step

length was also changed, but it didnt affect the

resolution.

Fig. 7 in three panels indicates the development of b-

value and standard deviation:

a) From 1960 to 2014 for BIN catalog from

International Institute of Earthquake Engineering and

Seismology, M2.5;

b) IRSC catalog from Institute of Geophysics, Tehran

University with M1.6;

c) Total data from BIN and IRSC catalog in the area

under study. An increase in b-value occurred after

the main shock.

Moreover, it followed by a decrease before the major

event in all the three graphs about weeks-months

before the earthquake. This increase in the b-value

proposes that there is a quiescence anomaly in the

region (Fig. 7). A significant decrease in b (t) is

followed by an increase in occurrence of large events

in the region.

2 3 4 5 6 7 8

100

101

102

103

Magnitude

Cumulative Number

Mcb-value = 0.565 +/- 0.01, a value = 4.72a value (annual) = 3.36


1.5 2 2.5 3 3.5 4 4.5 5 5.5 6

100

101

102

Magnitude

Cumulative Number

Mc



b a


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a) BIN Catalog (1960-2014)

b) IRSC Data (2006-2014)

C) Data (BIN + IRSC)

Fig. 7. b(t) of the Makran region during 1950-2014, data from a)

BIN catalog, b)IRSC catalog and c) BIN and IRSC catalog. Arrows mark in the three graph show the occurrence time of

mainshock event. Dotted lines indicate standard deviation in three graphs.

An earthquake occurred in Iran(Goharan), SE Iran on

May 11, 2013, Mw=6.2 (Fig. 3). A significant

decrease can be observed in the b(t) curve for this

earthquake (Fig. 8) which is indicative of a good

agreement between a sudden decrease in b(t) and the

occurrence of a large and strong earthquakes. Fig. (3)

displayed the seismicity of the region and the

location of Goharan earthquake. Therefore, an

increase in b-value occurred after 2010. There is a

distinct drop in b (t) before 2013. The data of the

study area in these Figures are related to the period

before May 11, 2013. The May 11, 2013 shock

(Mw=6.2) occurred in the low b-value area.

Fig. 8. b(t) of the Goharan region during 1960-2014 (BIN and

IRSC catalog).

3. DISCUSSION AND CONCLUSIONS

Historical and instrumental records in the MSZ have

shown that seismicity in eastern Makran is more

active than western Makran. The first instrumentally event in the Makran region occurred on November

28, 1945 with M=8.1. Our data indicated that

monitoring the variation of b-values and seismicity

before and after main shocks could help us to identify

the seismic activity in the region.

In this study, we tried to detect variations of b-value

in the Makran subduction zone by data from BIN and

IRSC networks. Our study showed that the main

shocks occurred where variations of b-value

decreased before these earthquakes. After a

comparison between b-values before and after main

shocks, we have observed a significant decrease of b-values several months before the main shock (April

16, 2013) in the region. Besides, we tested this

method for earthquake on May 11, 2013 that it is

also consistent with this conclusion. Our evidences

from b-value studies, especially the variation of b-

values was analyzed by frequency magnitude

distribution data in the region (56-63o E and 25- 29o

N) displayed that the western part of the area has

significant hazard. In this part, b-value variations are

1950 1960 1970 1980 1990 2000 20100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

b-value

Time ( year)

b-value

b

2007 2008 2009 2010 2011 2012 2013 20140

0.5

1

1.5

2

b-value

Time( year)

b-value

b

1950 1960 1970 1980 1990 2000 20100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

b-value

Time ( year)

b-value

b

1960 1970 1980 1990 2000 20100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

b-value

Time (year)

b-value

b

11 May 2013


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lower than the eastern part. Moreover, based on the

instrumentally data from IRSC and BIN Networks

(Figs. 9 a, b), there is an absence of notable large

events (M6) in the center of the region and a major

earthquake in the western part of MSZ that is visible

in seismicity data of the region.

Fig. 9. a, b- Seismicity map and location of an important historical earthquake in the western part; location map of seismic quiescence, red oval

shape in the Makran ranges, respectively. Asterisks represent earthquakes with magnitude more than 6.

On the other hand, GPS data studies have shown that

there is a differential movement between Oman and

Iran, and the shortening rate is about 1.95 cm/yr. This

event proves that there is an active subduction in the

region (Masson et al., 2007). Vernant et al., (2004)

have suggested that the convergence rate is 112

mm/yr at Jask, and it increases to 192 mm/yr at

Chabahar. Therefore, the evidence shows that the

seismicity in the western and eastern Makran is not

the same. In the western part of the study area and

the western part of Makran no earthquake with a magnitude bigger than 6.5 has been recorded.

Moreover, Rajendran et al., (2013) believed that

historical data by Ambraseys and Melville (1982)

seem ambiguous and incomplete as for the size and

location of earthquakes in the western part of

Makran. In addition, they have suggested that the

recent studies by Musson (2009) indicate a historical

event during AD 1483 in the study area in western

Makran (Fig. 9 a). a historical earthquake about more

than 500 years ago had happened in the region. This

long gap might lead to an important earthquake.

Thus, we believe that this region needs more

attention. Moreover, Minab- Zendan Fault system in

western part of the region is an important fault whose

lack of seismicity needs to be noted. This part of the region may produce major events in the future. The

observed aseismic portion of Makran zone -Figs. 9 (a

and b)- has a high potential for future earthquakes.

Therefore, seismic monitoring in this area of Makran

b

a


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provides increasingly better insights on the absence

of earthquake and the occurrence of large

earthquakes in space and time. We detected a

significant decrease of seismic b-values before

mainshock can be a strong method for studies of

future earthquakes in various places. Determination

of the b-value with time can be a useful research as

an earthquake precursor.

ACKNOWLEDGMENTS

The author would like to appreciate for the data used

in this study that were recorded by Broadband

Iranian National Network Center (BIN) and Iranian

Seismological Center (IRSC) Networks. The data

obtained from the International Institute of

Earthquake Engineering and Seismology (IIEES) and

Institute of Geophysics, University of Tehran web

sites.

REFERENCES

Aki K. (1965) Maximum lilkelihood estimate of b in the formula logN=a-bM and its confidence limits. Bulletin

Earthquake Research Institute, 43, 237-239.

Allen C., Amand P., Richter C. and Nordquist J. (1965) Relation between seismicity and geological structure in the

southern California region. Bulletin Seismology Society

American, 55, 752-797.

Ambraseys N. N. and Melville C. P. (1982) A history of Persian earthquakes. Cambridge University Press,

Cambridge, 219.

Apel E. Bu., rgmann R., Bannerjee P. and Nagarajan B. (2006) Geodetically constrained Indian plate motion and

implications for plate boundary deformation. Eos,

Transactions American Geophysical Union, 85(52), p. 51B-1524.

Argus D. F., Gordon R. G., Heflin M. B. Ma C. Eanes R.

J., Willis P., Peltier W. R. and Owen S. E. (2010) The angular velocities of the plates and the velocity of Earth's

centre from space geodesy. Geophysics Journal International, 180 (3), 913-960, Available from: doi:

10.1111/j.1365-246X.2009.04463.x.

Argus D. F. and Gordon R. G. (1991) No-net-rotation

model of current plate velocities in incorporating plate motion model NUVEL-1. Geophysics Research Letters,

18(11), 2039-2042, Available from: doi: 10.1029/ 91gl0 1532.

Bender B. (1983) Maximum likelihood estimation of b

values for magnitude grouped data. Bulletin Seismology Society American, 73(3), 831-851.

Byrne D. E. Sykes L. R. and Davis D. M. (1992) Great

thrust earthquakes and seismic slip along the plate

boundary of the Makran subduction zone. Journal of Geophysics Research, (97) 449478.

Bayer R., Chery J., Tatar M., Vernant P.h., Abbassi M.,

Masson F., Nilforoushan F., Doerflinger E., Regard V. and Bellier O (2006) Active deformation in ZagrosMakran

transition zone inferred from GPS measurements.

Geophysics Journal International, (165) 373381,

Available from: doi:10.1111/j.1365-246X.2006.02879.

Bufe C.G. (1970) Frequency-magnitude variations during the 1970 Danville earthquake swarm. Earthquake Notes, 41

(3), 3-6.

DeMets C., Gordon R. G., Argus D. F. and Stein S (1994)

Effect of recent revision to the geomagnetic reversal time scale on estimates of current plate motions. Geophysical

Research Letters, 21(20), 2191-2194.

DeMets C., Gordon R. G. and Argus D. F (2010) Geologically current plate motions. Geophysical Journal

International, 181 (1), 1-80.

Drewes H. (1998) Combination of VLBI, SLR, and GPS determined station velocities for actual plate kinematic and

crustal deformation models. in Geodynamics. edited by M.

Feissel, Springer.

Drewes H. and Angermann D. (2001) The actual plate kinematic and crustal deformation model 2000

(APKIM2000) as a Geodetic Reference System. in AIG 2001 Scientific Assembly, edited, Budapest.

Drewes H. (2009) The actual plate kinematic and crustal

deformation model APKIM 2005 as basis for a non-

rotating ITRF. in Geodetic Reference Frames, edited by H. Drewes, 95-99, Springer.

Ellouz-Zimmermann N. S., Lallemant R., Castilla-Chacon

N., Mouchot P., Leturmy A., Battani C., Buret L., Cherel G. Desaubliaux E., Deville J., Ferrand A., Lueckge G.,

Mahieux G., Mascle P., Muehr A.C. , Pierson-Wickmann P., Robion J., Schmitz M., Danish-Shaika S.I., Hasany I.,

Syed A. and Shahzad A. (2007) Offshore frontal part of the

Makran accretionary prism: the Chamak Survey (Pakistan), in Thrust belts and foreland basins: from fold

kinematics to hydrocarbon systems. Springer Series Frontiers in Earth Sciences, 351-366.

Gibowicz S.J. (1973) Variation of the frequency-magnitude

relation during earthquake sequences in New Zealand. Bulletin Seismology Society American, 63, 517-528.

Grando G. and McClay K. (2007) Morphotectonics

domains and structural styles in the Makran accretionary

prism, offshore Iran. Sedimentary Geology, 196 (1-4), 157-179.

Gripp A. E. and Gordon R. G. (1990) Current plate

velocities relative to the hotspots in incorporating the NUVEL-1 global plate motion model. Geophysics

Research Letters, 17 (8), 1109-1112, Available from: doi: 10.1029/GL017i008p01109.

Gripp A. E. and Gordon R. G. (2002) Young tracks of

hotspots and current plate velocities, Geophysics Journal

International, 150 (2), 321-361, Available from: doi: 10.1046/j.1365-246X.2002.01627.x.

Hatzidimitriou P., Papadimitriou Mountrakis D. and

Papazachos B. (1985) The seismic parameter b of the frequency-magnitude relation and its association with the

geological zones in the area of Greece, Tectonophysics, 120, 141-151.

Haghipour N. (2013) Active deformation and landscape evolution of the Makran Accretionary Wedge (SE-Iran),

new constraints from surface exposure dating of fluvial terraces. ETH Zrich, for the degree of Doctor of Sciences.


XLVII


Jolivet R., Duputel Z., Riel B., Simons M., Riversa L.,

Minson S., E, Zhang H., Aivazias M., Ayoub F., Leprince S., Samsonov S., Motagh M. and Fielding E. (2013) The

2013 Mw 7.7 Balochistan earthquake: Seismic potential of an accretionary wedge. Bulletin Seismology Society

American, Draft Accepted in BSSA.

Kanamori H. (1981) The nature of seismic patterns before

large earthquakes. In Earthquake Prediction: An International Review (eds. Simpson, D.W., and Richards,

P.G.), Maurice Ewing Series American Geophysical Union, 4, 1-19, Washington D.C.

Kreemer C., Holt W. E. and Haines A. J. (2003) An

integrated global model of present-day plate motions and plate boundary deformation. Geophysics Journal

International, 154 (1), 8-34, Available from: doi:

10.1046/j.1365-246X.2003.01917.x.

Kopp C., Fruehn J., Flueh E.R., Reichert C., Kukowski N., Bialas J. and Klaeschen D. (2000) Structure of the Makran

subduction zone from wide-angle and reflection seismic data. Tectonophysics, 329, 171191.

Mogi K. (1967) Regional variation in magnitude-frequency

relation of earthquake. Bulletin of the Earthquake Research

Institute, 45, 313-325.

McClusky S., Balassanian S., Barka A., Demir C., Ergintav S., Georgiev I., Gurkan, O., Hamburger K., Hurst

K., Kahle, H., Kastens, K., Kekelidze G., King R., Kotzev, V., Lenk, O., Mahmoud, S., Mishin A., Nadariya M.,

Ouzounis, A., Paradissis, D., Peter, Y., Prilepin, M., Reilinger, R., Sanli, H., Seeger, H., Tealeb A., Toksoz

M.N. and Veis G. (2000) Global Positioning System

constraints on plate kinematics and dynamics in the eastern Mediterranean and Caucasus. Journal of the Geophysics

Research, 105(B3), 56955719.

McClusky, S., Reilinger, R., Mahmoud, S., Ben Sari, D. & Tealeb, A. (2003) GPS constraints on Africa (Nubia) and

Arabia plate motions, Geophys. J. Int., 155, 126138.

Masson F., Anvari M., Djamour Y., Walpersdorf A., Tavakoli F., Daignieres M., Nankali H. and Van Gorp S.

(2007) Large-scale velocity field and strain tensor in Iran

inferred from GPS measurements: new insight for the present-day deformation pattern within NE Iran.

Geophyscs Journal International, 170, 436-440, Available from: doi: 10.1111/j.1365-246X.2007.03477.x.

Musson R. M. W. (2009) Subduction in the western

Makran: the historians contribution. Journal of the Geological Society of London,166, 387391.

Nuannin P. (2006) The Potential of b-value Variations as

Earthquake Precursors for Small and Large Events. Digital

Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 183.

Nuannin P., Kulhnek O. and Persson L. (2005) Spatial and

temporal b-value anomalies preceding the devastating off coast of NW Sumatra earthquake of December 26, 2004.

Geophysics Research Letters, 32 (L11307), Available from: doi: 10.1029/2005GL022679.

Prawirodirdjo L. and Bock Y. (2004) Instantaneous global plate motion model from 12 years of continuous GPS

observations. Journal of the Geophysics Research, 109 (B8), Available from: doi: 10.1029/2003jb002944.

Reilinger R., McClusky S., Vernant P., Lawrence S.,

Ergintav S., Cakmak R., Ozener H., Kadirov F., Guliev I., Stepanyan R., Nadariya M., Hahubia G., Mahmoud S.,

Sakr K., ArRajehi A., Paradissis D., Al-Aydrus A., Prilepin M., Guseva T., Evren E., Dmitrotsa A., Filikov S. V.,

Gomez F., Al-Ghazzi R. and Karam G. (2006) GPS

constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications

for the dynamics of plate interactions. Journal of the Geophysics Research, Solid Earth, 111, Available

from:doi: 10.1029/2005jb004051.

Rajendran C., P., Rajendran K, Shah-hosseini M, Nadei Beni A., Nautiyal C., M. and Andrews R. (2013) The

hazard potential of the western segment of the Makran

subduction zone, northern Arabian Sea. Nat Hazards, 65, 219-239, Available from: doi 10.1007/s11069-012-0355-6.

Szeliga W., Bilham R., Kakar D.M. and Lodi S. (2012)

Interseismic strain accumulation along the western boundary of the Indian subcontinent. Journal of

Geophysics Research, 117, B08404, Available from: http://dx.doi.org/10.1029/2011JB008822.

Sella G. F., Dixon T. H. and Mao A. (2002) REVEL: A

model for recent plate velocities from space geodesy.

Journal of Geophysical Research, 107(B4), 30 pp.

Scholz C.H. (1968) The frequency-magnitude relation of micro-fracturing in rock and its relation to earthquakes,

Bulletin Seismology Society American, 58, 399-415.

Tsapanos T. (1990) b-value of two tectonic parts in the circum-Pacific belt. Pure and Applied Geophysics

(PAGEOPH), 143, 229-242.

Vernant P., h., Nilforoushhan F., Hatzfeld D., Abbassi M.,

R., Vigny C., Masson F., Nankali H., Martinod J., Ashtiani A., Bayer R., Tavakoli F. and Chery J. (2004) Present-day

crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and Northern

Oman. Geophysics Journal International, 157, 381398.

Ustu T. (1965) A method in determining the value of b in a formula log N =a-bM showing the magnitude frequency for

earthquakes. Geophysics Bulletin Hokkaido University, 13,

99-103.

White R., S. and Louden K., E. (1982) The Makran Continental Margin: Structure of a Thickly Sediment

Convergent Plate Boundary: Convergent margins: Field investigations of margin structure and stratigraphy, Studies

in continental margin geology. American Association of Petroleum Geologists, 34 (M), 499-518.

Zare M., Ansari A., Heydari H., Shahvar M., Daneshdust

M., Mahdian M., Sinaiean F., Farzanegan E., Mirzaei-

Alavijeh, H. (2013) A Reconnaissance Report on two Iran, Makran Earthquakes ; 16 April 2013, Mw7.8, Gosht

(Saravan) and 11 May 2013 Iran (Goharan). Bashagard, SE of Iran.

Documents

Monitoring the Variations of b-Value and Seismicity in the Makran Ranges, the Absence of a Notable Event in West of Makran Subduction Zone