Generation and study of satellite gravity over Gujarat, India and their possible correlation with earthquake occurrences

Abstract

High-resolution satellite gravity data have been generated and utilized to infer subsurface geological structures in the area of devastating earthquake that struck the Bhuj region in Gujarat on 26 January 2001. Latitudinal gravity profiles have been generated in the Bhuj, Anjar and IBF regions across the epicentres (23.5° N, 69.8° E/M_w 7.0 in 2001; 23.2° N, 70° E/M_w 7.0 in 1956; 24.2° N, 69.2° E/M_w 7.8 in 1819). Substantial differences in gravity anomaly patterns as high as 37 mGal could be observed existing near the epicentre regions. These gravitational differences might have caused due to the plate tectonic processes and due to the changes in densities of different lithospheric zones/sedimentary layers. Temporal variations of the satellite-derived gravity and their probable relations with already occurred major earthquakes in this region have been studied. Hence we conclude that drastic changes in gravity anomalies can be considered as a precursor for occurrences of substantially large earthquakes.

Keywords:

• earthquake
• regional faults
• free-air gravity
• GRACE
• Kachchh region
• spatial and temporal variation of gravity

Acknowledgements

The authors are very much thankful to Prof. C. Hwang, National Chiao Tung University, Taiwan for providing very high resolution satellite gravity data and the related software. The authors are also thankful to the anonymous referees for their comments and suggestions for the improvement of the manuscript. They also thank Dr. R. R. Navalgund, Director, SAC, Dr. J. S. Parihar, DD, RESA and Dr. Ajai, GD, MESG for their keen interest in this study.