Tectonic Framework of the Kachchh Earthquake of 26 January 2001

Talwani, Pradeep; Gangopadhyay, Abhijit

doi:10.1785/gssrl.72.3.336

Cited by 97 publications

(45 citation statements)

References 20 publications

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“…The Kachchh rift zone is bounded by two major faults namely, the Nagar-Parkar Fault (NPF) in the north and North Kathiawar Fault (NKF) in the south. The Kachchh rift zone was initially subjected to extension but now is under N-S compression since 20 Ma (TALWANI and GANGOPADHYAY, 2001). The Kachchh basin has the most complete Mesozoic (135-65 Ma) record with a thick accumulation (3000 m) of Late Tertiary to Lower Cretaceous sediments (BISWAS, 1987).…”

Section: Kachchhmentioning

confidence: 99%

Probabilistic Assessment of Earthquake Hazard in Gujarat and Adjoining Region of India

Yadav

Tripathi

Rastogi

et al. 2008

Pure appl. geophys.

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The Gujarat and adjoining region falls under all four seismic zones V, IV, III and II of the seismic zoning map of India, and is one of the most seismically prone intracontinental regions of the world. It has experienced two large earthquakes of magnitude M w 7.8 and 7.7 in 1819 and 2001, respectively and several moderate earthquakes during the past two centuries. In the present study, the probability of occurrence of earthquakes of M C 5.0 has been estimated during a specified time interval for different elapsed times on the basis of observed time intervals between earthquakes using three stochastic models namely, Weibull, Gamma and Lognormal. A complete earthquake catalogue has been used covering the time interval of 1819 to 2006. The whole region has been divided into three major seismic regions (Saurashtra, Mainland Gujarat and Kachchh) on the basis of seismotectonics and geomorphology of the region. The earthquake hazard parameters have been estimated using the method of maximum likelihood. The logarithmic of likelihood function (ln L) is estimated and used to test the suitability of models in three different regions. It was found that the Weibull model fits well with the actual data in Saurashtra and Kachchh regions, whereas Lognormal model fits well in Mainland Gujarat. The mean intervals of occurrence of earthquakes are estimated as 40.455, 20.249 and 13.338 years in the Saurashtra, Mainland Gujarat and Kachchh region, respectively. The estimated cumulative probability (probability that the next earthquake will occur at a time later than some specific time from the last earthquake) for the earthquakes of M C 5.0 reaches 0.9 after about 64 years from the last earthquake (1993) in Saurashtra, about 49 years from the last earthquake (1969) in Mainland Gujarat and about 29 years from the last earthquake (2006) in the Kachchh region. The conditional probability (probability that the next earthquake will occur during some specific time interval after a certain elapsed time from last earthquake) is also estimated and it reaches about 0.8 to 0.9 during the time interval of about 57 to 66 years from the last earthquake (1993) in Saurashtra region, 31 to 51 years from the last earthquake (1969) in Mainland Gujarat and about 21 to 28 years from the last earthquake (2006) in Kachchh region.

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Section: Kachchhmentioning

confidence: 99%

Probabilistic Assessment of Earthquake Hazard in Gujarat and Adjoining Region of India

Yadav

Tripathi

Rastogi

et al. 2008

Pure appl. geophys.

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“…The region is a tri-junction of three failed rifts: Kachchh, Cambay and Narmada with several active faults (BISWAS, 1987(BISWAS, , 2005TALWANI and GANGOPADHYAY, 2001). These rifts were formed by rifting along major Precambrian trends.…”

Section: Geology and Tectonics Of The Gujarat Regionmentioning

confidence: 99%

Estimation of Strong Ground Motions for 2001 Bhuj (M w 7.6), India Earthquake

Chopra

Kumar

Rastogi

2010

Pure Appl. Geophys.

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The strong ground motions for the 2001 Bhuj (M w 7.6) India earthquake have been estimated on hard rock and B/C boundary (NEHRP) levels using a recently modified version of stochastic finite fault modeling based on dynamic corner frequency (MOTAZEDIAN and ATKINSON in Bull Seismol Soc Am 95, 995-1010 2005). Incorporation of dynamic corner frequency removes the limitations of earlier stochastic methods. Simulations were carried out at 13 sites in Gujarat where structural response recorder (SRR) recordings are available. In addition, accelerograms were simulated at the B/C boundary at a large number of points distributed on a grid. The corresponding response spectra have also been estimated. The values of peak ground accelerations and spectral accelerations at three periods (0.4, 0.75 and 1.25 s) are presented in the form of contour maps. The maximum value of peak ground acceleration (PGA) in the center of meizoseismal zone is 550 cm/s 2 . The response spectral acceleration in same zone is 900 cm/s 2 (T = 0.4 s), 600 cm/s 2 (T = 0.75 s) and 300 cm/s 2 (T = 1.25 s). The innermost PGA contour is on the fault plane. A comparison of the PGA values obtained at 13 sites in this study with those obtained in earlier studies on the same sites, but employing different methods, show that the present PGA values are comparable at most of the sites. The rate of decay of PGA values is fast at short distances as compared to that at longer distances. The PGA values obtained here put some constraints on the expected values from a similar earthquake in the region. A synthetic intensity map has been prepared from the estimated values of PGA using an empirical relation. A comparison with the reported intensity map of the earthquake shows the synthetic MMI values, as expected, are lower by 1 unit compared to reported intensity map. The contour map of PGA along with the contour maps of spectral acceleration at various periods permit the assessment of damage potential to various categories of houses and other structures. Such information will be quite important in planning of mitigation and disaster management programs in the region.

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“…1). In addition to the east-west trending faults, several north-south, northeast-southwest and northwest-southeast trending tectonic lineaments and various local faults have also been reported in the region (BISWAS and DESHPANDE, 1970;TALWANI and GANGOPADHYAY, 2001;KAYAL et al, 2002).…”

Section: Geologic and Tectonic Setupmentioning

confidence: 99%

“…Tectonic framework suggests that the Kachchh Basin provides a local weak volume in the stable continental region, where in response to the N-S compressional stresses, large strain accumulation is possible that leads to high seismicity (TALWANI and GANGOPADHYAY, 2001). This is evidenced by the occurrence of several moderate to large-sized earthquakes in the region, namely the Samaji town earthquake of May 1668 (MMI intensity X), the Rann of Kachchh earthquake of June 16, 1819 (MMI intensity XI; M w % 7.8), the Lakpat earthquake of April 19, 1845 (MMI intensity VIII) and the Anjar earthquake of July 21, 1956 (MMI intensity IX; M w % 6.0) (TANDON, 1959;CHANDRA, 1977;CHUNG and GAO, 1995).…”

Section: Geologic and Tectonic Setupmentioning

confidence: 99%

Coda Q in the Kachchh Basin, Western India Using Aftershocks of the Bhuj Earthquake of January 26, 2001

Gupta

Kumar

Shukla

et al. 2006

Pure appl. geophys.

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Q C -estimates of Kachchh Basin in western India have been obtained in a high frequency range from 1.5 to 24.0 Hz using the aftershock data of Bhuj earthquake of January 26, 2001 recorded within an epicentral distance of 80 km. The decay of coda waves of 30 sec window from 186 seismograms has been analysed in four lapse time windows, adopting the single backscattering model. The study shows that Q c is a function of frequency and increases as frequency increases. The frequency dependent Q c relations obtained for four lapse-time windows are: Q c =82 f 1.17 (20-50 sec), Q c =106 f 1.11 (30-60 sec), Q c =126f 1.03 (40-70 sec) and Q c =122f 1.02 (50-80 sec). These empirical relations represent the average attenuation properties of a zone covering the surface area of about 11,000, 20,000, 28,000 and 38,000 square km and a depth extent of about 60, 80, 95, 110 km, respectively. With increasing window length, the degree of frequency dependence, n, decreases marginally from 1.17 to 1.02, whereas Q 0 increases significantly from 82 to 122. At lower frequencies up to 6 Hz, Q c )1 of Kachchh Basin is in agreement with other regions of the world, whereas at higher frequencies from 12 to 24 Hz it is found to be low. Figure 1 Map showing epicenters of aftershocks of Bhuj earthquake used in the Q c analysis, tectonic features in the Kachchh Basin and the locations of recording stations.

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Tectonic Framework of the Kachchh Earthquake of 26 January 2001

Cited by 97 publications

References 20 publications

Probabilistic Assessment of Earthquake Hazard in Gujarat and Adjoining Region of India

Probabilistic Assessment of Earthquake Hazard in Gujarat and Adjoining Region of India

Estimation of Strong Ground Motions for 2001 Bhuj (M w 7.6), India Earthquake

Coda Q in the Kachchh Basin, Western India Using Aftershocks of the Bhuj Earthquake of January 26, 2001

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