Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

HISTORICAL SEISMICITY AND EARTHQUAKECATALOGUES FOR THE INDIAN REGIONH. N. Srivastava and S. K. DasIndia Meteorological DepartmentLo& Road, New Delhi - 110009, IndiaABSTRACTSeismicity of the Indian region is discussed in the light of the historicaldata vis a vis expansion of seismological network in the country. Thesources of epicentral data for this region are based on monthly seismologicalbulletins prepared by the India Meteorological Department, U.S.Geological Survey and International Seismological Centre, and cataloguesof earthquakes by Tandon and Srivastava (1974) and many others. Thelimitations of these catalogues are discussed. The utility of a new catalogueof earthquakes in peninsular India for the period 1849 to 1900,based on felt reports through three newspapers (Times of India, Statesmanand Hindu) is briefly discussed. This catalogue has brought out someinteresting results. In particular, it has been noticed that in the regionwhere significant earthquakes have occurred, tremors of felt intensity havebeen reported several years preceding the main events. Recently, earthquakesof similar intensity, as reported in the catalogue, have occurrednear Hyderabad (30 June 1983; magnitude 4.8) and Bangalore (20 March1985; magnitude 4.5) showing its utility in assessment of earthquake risk.The India Meteorological Department is participating in the IASPEIHistorical Seismogram Filming Project and more than 20,000 seismogramsof Bombay have been microfilmed during the last two years. The recenttechniques of source mechanism studies through digitieation of old records(prior to 1962), as envisaged in the TASPEI Historical Seismogram FilmingProject, will enable us to understand the nature of stresses in andaround the Indian plate.1. IntroductionThe Himalayan mountain system has been developing since early Mesozoic time.It is attributed to the underthrusting of the Indian plate below the Eurasian plate.These movements are still continuing and are associated with active seismicity of theregion where several great earthquakes (Assam 1897 and 1950, Kangra 1905, BiharNepal 1934) have caused huge loss of life and property. Although plate movementshave been taking place for millions of years, a reliable history of great earthquakesin the Indian region extends back only 200 years. Of this time period, epicentralparameters of earthquakes based on instrumental data are available for less than acentury.The objective of this paper is to evaluate the importance of historical seismicityfor the Indian region. This paper describes the limitations of earthquake cataloguesfor the region. The utility of the new catalogue of earthquakes for the period 1840 to1900, based on felt reports for peninsular India, and the importance of the IASPEIHistorical Seismogram Filming Project are discussed.Historical Seismogramsand Earthquahes of the World335Copyright 0 1 Yhb: by .4cademic Press, Inc.All rights of reproduction in any form reserved.