1988年ネパール・インド国境地震の災害調査

Abstract

The earthquake we have investigated took place in the Nepal-India border region in the earlymorning on 21 August 1988. This earthquake in the southeastern zone of Nepal close to the bor-der of the State of Bihar, India registered 6.6 on the Richter Scale. Its focal depth was assumedto be 57 km. In Bihar State, India, 282 persons died, 3766 were injured and 150, 000 houses weredamaged. In Nepal, 721 persons died, more than 5000 were injured and 100, 000 houses weredamaged. Most the houses damaged had been constructed of stone cemented with mud mortar, unburnt bricks, or burnt brick masonry. There are many wooden houses and few reinforced con-crete buildings in the effected area. We did not find any serious damage to those structures.This is a survey report, in which the damage to human loss and the collapse of buildingstructures done by the earthquake are introduced and discussed. We estimated the fault zone ofthis earthquake from the post-earthquake records. The intensity of ground shaking around theeffected areas is discussed in terms of assumed fault parameters and the geological condition ofthe surface layer. We also prepared a questionnaire asking inhabitants. The intensity distribu-tion estmated from their information is compared with the intensity derived from seismographicdata. Based on our laboratory tests of sand specimens collected from riversides where liquefac-tion occurred during the earthquake, the maximum acceleration near the epi-center is also esti-mated. The strength of the structures in the effected areas is estimated and compared with theactual damage done. On the basis of our survey and analytical results we present some recom-mendations for the mitigation of earthquake disasters in these areas.