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

ON THE SEISMICITY OF THE MIDDLEASTSamir RiadGeology DepartmentAssiut University, Assiut, EgyptHerbert MeyersWorld Data Center-A for Solid Earth GeophysicsBoulder, CO 80303, USACarl KisslingerCIRES and Department of Geological SciencesUniversity of Colorado, Boulder, CO 80303, USAABSTRACTMiddle East earthquake data were collected from various files at theWorld Data Center and from several other publications. Earthquakes ofmagnitude mg 2 4.5 or of intensity I, 2 VI for the period 1900-83 wereconsidered in the present study. The total number of these events wasabout 8,000, of which 2,400 were reported as suspected duplicates. Duplicateswere removed by giving preference to those sources that reevaluatedearthquake parameters and to those that included more complete or recentinformation.Relations between the reported values of mb, Ms, ML, and I, wereobtained and then used to assign calculated values for all events. TheMs/mg relation for the Middle East was obtained using 405 events, inthe form:Ms = 1.604mb - 3.374 f 0.49.The range of magnitude used was 4.5 - 7.1 and 3.2 - 7.4 for mb and Ms,respectively. The relation between ML and I, was obtained, using 438events, in the form:(1)M, =z 0.51, + 1.36 log h - 0.133 zk 0.44. (2)Relations between other parameters were also deduced for the MiddleEast as a whole and for selected areas in the Middle East.The collected data were used in this way to compile an earthquake catalogof the Middle East, with lower limit of MS > 3.9, which correspondsapproximately to a value of mg 2 4.5 and I, 2 V.Recurrence-rate relations for the Middle East have been derived andare given in the form:log N = 7.73 - 1.306 M,, (3)log N = 8.44 - 0.97910, (4)where N is the cumulative number of events per year of magnitude 2 MLor intensity 2 I,. Similar relations also were obtained for selected areas.Historical Seismogramsand Earthquakes of the World321Copyright 0 1988 by Academic Press, Inc.All rights of reproduction in any form reserved.