Document Type : Original Research Paper
Authors
1 M. Sc., Department of Geology, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Assistant Professor, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran
3 Ph. D.,Geological Survey of Iran, Tehran, Iran
4 Professor, Department of Geology, Islamic Azad University, North Tehran Branch, Tehran, Iran
Abstract
The purpose of this research is to study active faulting in western part of the Middle East, between Caspian Sea to the east and Mediterranean Sea to the west. This region covers several countries and thus geological maps have different scale and errors in locations. The mismatch between fault traces in geological maps with their actual position on the ground is sometimes up to several hundred meters. The main goal of this study was to prepare continues map of active faults together with seismicity for the entire region of interest. This map also shows the slip rate of the active faults, estimated based on available geodetic measurements (GPS) or other published data. All available information including geological maps, satellite images, topographic data, GPS measurements, and earthquake data were imported into Arc GIS system. The Landsat 7 satellite images were used to correct location of active faults and measuring young offsets along the faults. Most of active faults bound the mountains implying that they control current topography of the region. The earthquakes are more frequent in the Zagros, especially in western part, around junction of the North and East Anatolian faults. This is in contrast with the Dead Sea region where lower seismic activity observed. However larger earthquakes are distributed over entire region, though we have more record of historical earthquakes in NW Iran, Eastern Turkey and the Dead Sea region probably related to documentation of historical data rather than occurence of earthquakes. In the eastern Zagros (NW of Iran) total shortening is partitioned into pure strike-slip and thrusting. In the middle part (eastern Turkey) the Zagros trends east-west and most of shortening is taken up by pure thrusting. The Central and Eastern Turkey is dominated by strike-slip faults and rotation of blocks. Shortening across left-lateral and right-lateral systems in eastern Turkey cause the Turkish block to move to the west and subduct in Hellenic trench. Comparing rate of shortening with moment released by earthquakes in Zagros and Caucuses suggest that part of shortening is taking up by creep.
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