Bihar Nepal Earthquake (August 20, 1988)

Contents: 1. Introduction. 2. Earthquake parameters. 3. Geomorphology and geology. 4. Earthquake effects and associated features. 5. Isoseismal studies. 6. Tectono-geologic framework of the eastern Gangetic Foredeep. 7. Seismotectonics of the Eastern Himalaya and its Foredeep . References. Appendix. Locality Index.

From the summary: "During the early hours of Sunday, the 21 August, 1988 (mid-night of 20 August as per International date and time) an Earthquake rocked severely the entire North Bihar and adjacent areas of East Nepal, Sikkim and Darjeeling in West Bengal, Darbhanga and Madhubani were the worst affected districts, but damages of gradually diminishing intensity extended up to Ranchi and Palamau in Bihar, Sikkim and Darjeeling of West Bengal. The Earthquake caused collapse of about 50,000 houses in the entire area and reported to have killed 300 people in North Bihar and 700 in Nepal.

"Based on the damage records, isoseismal map of the present Earthquake delineating the zones of intensity according to the Modified Mercalli Scale has been prepared and presented in the report. The control for drawing firm conclusion regarding intensity in the high intensity zones of VIII & IX are somewhat tentative due to rural setting, where good masonry buildings are few and far between. The situation was further aggravated due to waterlogging, as a result of heavy rains.

"An attempt has been made towards identification of the possible fault, its nature, type of movement etc. that triggered the August, 1988 Earthquake, from available geological, geophysical and seismological informations from the Eastern Gangetic Foredeep. The study has indicated the East Patna fault responsible for the August, 1988 Earthquake, as the epicentre directly correlates with this fault. The study has also emphasised that all other faults between Motihari and Kishanganj to be equally potential for seismic hazard, as they form a part of the same fault system. Keeping in view the seismic hazard, potential of the pre-Neogene fault system, traversing the Gangetic plains, orientation of priorities for hazard mitigation has been recommended."