Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

B. K. Rastogi ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad-500 007, IN

Abstract

The paper presents the results of damage survey for the Chamoli earthquake of Ms 6.6 (USGS) on March 29,1999. Fifteen strong aftershocks of M≥4.0 (including 5 of M≥5.0) were recorded within 20 days of the mainshock. The hypocentre given by US Geological Survey (30.55°N; 79.424E; focal depth 15 km) is south of the Main Central Thrust (MCT) and north of the meizoseismal area. The fault plane (strike 282°; dip 9° N; slip 95°) indicates thrusting along the detachment surface at a depth of 15 km below the MCT. The rupture is inferred to have started near the hypocentre and progressed southward giving maximum moment release in the meizoseismal area. The maximum damaged area of MM Intensity VIII assigned from field observations is about 10 km x 5 km, extending in WNW-ESE direction from Charnoli to Mandal. The other isoseismals also trend WNW-ESE. The areas covered by isoseismals VII, VI and V are 120 km x 70 km, 280 km x 190km and 525km x 670 km respectively, which yield M_w oF6.3 using the empirical relations given for stable continental regions. This M_w is same as 6.3 obtained from moment-tensor analysis. However, Intensity V area (525 km x 670 km or less) is observed to be less as compared to that in SCR regions for such earthquakes as it yields a smaller value of M_w. From the list of 13 earthquakes in the past 97 years in Kumaon-Garhwal region, M≥6.0 earthquakes seem to repeat every eight years in this region.

Keywords

Seismology, Earthquakes, Chamoli Earthquake, Seismicity, Himalaya, India.

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M. Ramakrishnan ¹, B. K. Rastogi ², P. L. Narula ³, V. P. Kamble ⁴, G. D. Gupta ⁵

Affiliations
1 Geological Survey of India, Hyderabad, IN
2 National Geophysical Res Inst, Hyderabad, IN
3 Geological Survey of India, Lucknow, IN
4 India Meteorological Dept., New Delhi, IN
5 Dept. of Science and Technology, New Delhi, IN

Abstract

No Abstract.

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Sumer Chopra ¹, K. Madhusudhan Rao ¹, B. Sairam ¹, Santosh Kumar ¹, A. K. Gupta ¹, Hardik Patel ¹, M. S. Gadhavi ¹, B. K. Rastogi ¹

Affiliations
1 Institute of Seismological Research, Sector-18, Gandhinagar - 382 018, IN

Abstract

About 200 shocks were felt and over 50 of M-2 to 4 were located south of Jamnagar in 2006 and same number was felt/located again in 2007 with blast like subterranean sounds soon after heavy rains. Most of the shocks have shallow focal depth of less than 10 km. Some of the tremors have caused cracks in a few houses. During September-October 2006 tremors were confined withm 5 km of Khankotda village which is about 30 km SE of Jamnagar. During August-September 2007 the activity had spread northward up to Jamnagar. Some shocks have occurred about 20-25 km west of this trend faults/lineaments/dykes in the area are studied to identify the causative feature for the tremors. The rainfall data of the district and water level data of nearby observation wells are studied to see any possible relationship with earthquake activity. Data of about hundred cases of swarm type of earthquake sequences in the peninsular India in last several decades are compiled to study their characteristics vis-a-vis monsoons.

Keywords

Swarm-Type of Earthquakes, Subterranean Sounds, Saurashtra Seismicity.

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B. K. Rastogi ¹, R. K. Jaiswal ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

Seismic characteristics like frequency-magnitude relation, decay rate of aftershocks, foreshock-aftershock pattern and energy release are studied for earth tremors of magnitude ≤ 4.3 that occurred near Tirupattur town of North Arcot District of Tamilnadu during November 27, 1984 to February 23, 1985. These characteristics are interpreted in terms of ambient stress level and mechanical properties of rock media. An isoseismal map has been prepared from the felt reports and damage survey. This sequence was the first in the region that was well recorded at regional stations enabling inferences about seismotectonics of the region.

Keywords

Seismotectonics, Earth Tremors, Tirupattur Town, N.Arcot District, Tamil Nadu.

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B. K. Rastogi ¹

Affiliations
1 Director General, Institute of Seismological Research, Sector-18, Gandhinagar -382018, IN

Abstract

No Abstract.

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Eugene Schweig ¹, Joan Gomberg ¹, Mark Petersen ², Michael Ellis ³, Paul Bodin ³, Laurel Mayrose ³, B. K. Rastogi ⁴

Affiliations
1 U S Geological Survey Memphis, TN 38152, US
2 U S Geological Survey, Golden, CO - 80446, US
3 Center for Earthquake Research and Information, The University of Memphis, Memphis - 38152, TN, US
4 National Geophysical Research Institute, Hyderabad-50 007, IN

Abstract

The Mw 7 7 Bhuj earthquake occurred in the Kachchh District of the State of Gujarat, India on 26 January 2001, and was one of the most damaging intraplate earthquakes ever recorded. This earthquake is in many ways similar to the three great. New Madrid earthquakes that occurred in the central United States in 1811-1812. An Indo- US team is studying the similarities and differences of these sequences in order to learn lessons for earthquake hazard in intraplate regions Herein we present some preliminary conclusions from that study Both the Kutch and New Madrid regions have rift type geotectonic setting. In both regions the strain rates are of the order of 10⁹/yr and attenuation of seismic waves as inferred from observations of intensity and liquefaction are low. These strain rates predict recurrence intervals for Bhuj or New Madrid sized earthquakes of several thousand years or more. In contrast, intervals estimated from paleoseismic studies and from other independent data are significantly shorter, probably hundreds of years. All these observations together may suggest that earthquakes relax high ambient stresses that are locally concentrated by rheologic heterogeneities, rather than loading by plate-tectonic forces. The latter model generally underlies basic assumptions made in earthquake hazard assessment, that the long-term average rate of energy released by earthquakes is determined by the tectonic loading rate, which thus implies an inherent average periodicity of earthquake occurrence. Interpreting the observations in terms of the former model therefore may require re-examining the basic assumptions of hazard assessment.

Keywords

Earthquake, Intra-Plate Regions, Periodicity, Hazard Assessment, Bhuj, Kachchh, New Madrid, Central USA.

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B. K. Rastogi ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

No Abstract.

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Harsh K. Gupta ¹, T. Harinarayana ¹, M. Kousalya ¹, D. C. Mishra ¹, Indra Mohan ¹, N. Purnachandra Rao ¹, P. S. Raju ¹, B. K. Rastogi ¹, P. R. Reddy ¹, D. Sarkar ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

No Abstract.

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B. K. Rastogi ¹

Affiliations
1 Institute of Seismological Research, Sector-18, Gandhinagar - 382 018, IN

Abstract

No Abstract.

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B. K. Rastogi ¹

Affiliations
1 Institute of Seismological Research, Gandhingar - 382 009, IN

Abstract

The Indo-US workshop on Intraplate Seismicity was held at Institute of Seismological Research, Gandhinagar, Gujarat during January 15-18, 2012 andwas supported by Indo-US Science & Technology Forum (IUSSTF), New Delhi and Coordinated by BK Rastogi, Director General, Institute of Seismological Research, Gandhinagar, India and Susan E Hough, US Geological Survey, Pasadena, CA, (Email:hough@gps.caltech.edu). Scientific agenda was to take stock of Intraplate Seismicity study in USA and India and chart the future directions to understand this phenomenon.

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