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

322 S. Riad, H. Meyers, and C. KisslingerThese relations are used to obtain the mean return period for events ofmagnitude equal to or larger than a given magnitude ML. For the MiddleEast, the following relation may be used:t ( ~ = ~ 101.306M~ ) - 7-73years, (5)which gives an average return period equal to 25 years for events ofML 2 7.0.The value of b given by equation (3) above, log N = a+bML shows thatthe study area belongs to relatively young orogenic belt zones. Values of bequal to 0.65, 1.4, and 1.8 were found for Pakistan, Turkey, and southernIran, respectively.1. IntroductionThe Middle East covers an area of more than 13 million square kilometers, includingcountries geographically belonging to three different continents. It also includesareas that have significant differences in their tectonic evolution - the spreadingcenter and formation of new oceanic crust in the Red Sea, the transcurrent faultingand rifting in the Dead Sea area, the collision and subduction in the easternMediterranean, and the subduction and thrusting in western Iran. Therefore, theearthquake activity and seismotectonics of each of these areas definitely will bedifferent.The major part of the Middle East is comprised of developing countries. Someof them are oil producing, and a major part of their revenues is used in socialand economic development. Complete towns and large engineering establishmentshave been built, and the development is still continuing. Many of the Middle Eastcountries are planning to build nuclear power plants.Different parts of the Middle East have been affected by destructive earthquakesin historic times. Great property damage and loss of life have been reported inrecent times (Ganse and Nelson, 1981; Ambraseys and Melville, 1983; Barazangiand Rouhban, 1983). With the present trend of social and economic development,the socio-economic hazards of earthquakes also increase.Reliable seismological and seismotectonic studies have not been done in manyparts of the Middle East. These kinds of studies are necessary for reliable site studiesand design factors for nuclear power plants, as well as other major engineeringprojects. They also are essential to reduce the socio-economic impact of earthquakehazards.Study of the seismicity and seismotectonics of an area depends largely on theavailability of information and its completeness and reliability. Therefore, an earthquakecatalog for the Middle East countries has been prepared and used to compilea seismicity map of the Middle East at a scale 1:8,000,000. The aim of the presentpaper is to present the main information included in the catalog, and to providedetailed seismicity relations for selected areas in the Middle East.The prepared catalog includes 47 regions (Flinn and Engdahl, 1965) that coverthe Middle East countries (Figure 1). Table 1 shows the geographic locations ofthese regions. Earthquake data were collected from different files at the WorldData Center, Boulder, Colorado, USA, and from other published catalogs (Ganseand Nelson, 1981; Ben-Menahem, 1979; Ktirnik, 1969) and from individual articles (Ambraseys, 1978; Ambraseys and Melville, 1982, 1983; and Barazangi and