Intensity map of Mw 6.9 2011 Sikkim–Nepal border earthquake and its relationships with PGA: distance and magnitude

• Published in: Natural hazards (Dordrecht) Vol. 69; no. 3; pp. 1781 - 1801
• Main Authors: Prajapati, Sanjay K., Kumar, Ashok, Chopra, Sumer, Bansal, B. K.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.12.2013; Springer; Springer Nature B.V
• Subjects: Alluvium; Attenuation; Borders; Civil Engineering; Damage; Deltas; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Earthquake damage; Earthquakes; Electronics; Engineering and environment geology. Geothermics; Environmental Management; Exact sciences and technology; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Ground motion; Himalayas; Hydrogeology; Mud flats; Natural Hazards; Natural hazards: prediction, damages, etc; Original Paper; Regression analysis; Salt flats; Seismic activity; Seismic phenomena; Sikkim India; Asia; Indian Peninsula; Himalayas; Nepal; India; Pakistan, Himalayas; India, Sikkim; ISW, India; Attenuation; Earthquake; Sikkim; Intensity; rivers; attenuation; maps; regression analysis; least-squares; ground motion; earthquakes; mud flats; planning; natural disaster damages; fault displacements; alluvium; seismic intensity; deltas
• ISSN: 0921-030X; 1573-0840
• DOI: 10.1007/s11069-013-0776-x

We compiled available information of damages and other effects caused by the September 18, 2011, Sikkim–Nepal border earthquake from the print and electronic media, and interpreted them to obtain Modified Mercalli Intensity (MMI) at over 142 locations. These values are used to prepare the intensity map of the Sikkim earthquake. The map reveals several interesting features. Within the meizoseismal area, the most heavily damaged villages are concentrated toward the eastern edge of the inferred fault, consistent with eastern directivity. The intensities are amplified significantly in areas located along rivers, within deltas or on coastal alluvium such as mud flats and salt pans. We have also derived empirical relation between MMI and ground motion parameters using least square regression technique and compared it with the available relationships available for other regions of the world. Further, seismic intensity information available for historical earthquakes which have occurred in NE Himalayas along with present intensity has been utilized for developing attenuation relationship for NE India using two-step regression analyses. The derived attenuation relation is useful for assessing damage of a potential future earthquake (earthquake scenario-based planning purposes) for the northeast Himalaya region.