Understanding local soil effect upon earthquake ground motion for the city of Guwahati city

Various damages reported during 1869 Cachar EQ (M-7.8) in Guwahati. (a) House damage in Pan Bazaar; (b) wider ground cracks in the Pan bazaar area; (c) ground subsidence on the bank of River Brahmaputra; (d) Ground Fissures on the bank of river Brahmaputra. (Modified after Oldham 1882).
Various damages reported during 1869 Cachar EQ (M-7.8) in Guwahati. (a) House damage in Pan Bazaar; (b) wider ground cracks in the Pan bazaar area; (c) ground subsidence on the bank of River Brahmaputra; (d) Ground Fissures on the bank of river Brahmaputra. (Modified after Oldham 1882)

North-East seismicity of India is a combined effect of Indian-Eurasian Plate boundary in the north and the Burmese arc in the east. The region has been considered among the top six most seismically active regions of the world. Other similar seismicity regions include San Andreas in United States, Guerrero region in Mexico and regions of Japan, Taiwan and Turkey.

The city of Guwahati is the largest industrial and business centre of the entire North-east India. The city is located on the bank of river Brahmaputra covering an area of approximately 600 sq km with its center at 26O08 N and 91O40 E. As per census 2011, the city holds a population of approximately 1 million residents. Considering the seismic scenario of the city, it is surrounded by the Main Central thrust in the north, Dhubri fault in the west, Dauki fault in the south and Naga thrust in the east. Thus, the city of Guwahati lies in between the active Himalayan belt and the Shillong plateau. A close observation of reported damages during the past earthquake suggests wide scattered damages in different parts of Guwahati. Keeping in mind the seismic potential of the seismotectonic province of Guwahati and the past reported damages, this project is an attempt to understand the local site effects for the plane area of Guwahati.

Under start-up grant funded by Indian Institute of Technology, Guwahati.