Content area
Full Text
Nat Hazards (2013) 69:17811801
DOI 10.1007/s11069-013-0776-x
ORIGINAL PAPER
Sanjay K. Prajapati Ashok Kumar Sumer Chopra
B. K. Bansal
Received: 21 March 2013 / Accepted: 5 July 2013 / Published online: 20 July 2013 Springer Science+Business Media Dordrecht 2013
Abstract We compiled available information of damages and other effects caused by the September 18, 2011, SikkimNepal border earthquake from the print and electronic media, and interpreted them to obtain Modied 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 amplied signicantly in areas located along rivers, within deltas or on coastal alluvium such as mud ats 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.
Keywords Earthquake Sikkim Intensity Attenuation
1 Introduction
On September 18, 2011 at 12:40 UTC (06:10 p.m. local time), an Mw 6.9 moderate magnitude earthquake struck SikkimNepal border region. The epicenter was located 64 km NW of Gangtok, the capital city of Sikkim. The earthquake occurred within the Indo-Eurasian collision zone and caused severe ground shaking across north Indian region and adjoining areas. The earthquake caused devastation in Sikkim and its adjoining areas, disrupting the road network, damaging structures of commercial, public and religious importance. The
S. K. Prajapati (&) A. Kumar S. Chopra B. K. Bansal
Seismology Division, Ministry of Earth Sciences, New Delhi 110003, India e-mail: [email protected]
Intensity map of Mw 6.9 2011 SikkimNepal border earthquake and its relationships with PGA: distance and magnitude
123
1782 Nat Hazards (2013) 69:17811801
earthquake was shallow-focus event, and lasted for about 3040 s. The event was widely felt in Assam,...