Erzurum, Turkey Earthquake

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Posting Date: March 26, 2004, 10:00:00 AM

A moderate earthquake struck eastern Turkey on Thursday, March 25, 2004, at about 7:30 p.m. local time (19:30 UTC). The U. S. Geological Survey (USGS), which located the earthquake center at 25 miles (35km) west of Erzurum and about 425 miles (685 km) east of Ankara, the capital, has initially estimated the moment magnitude at 5.5, with a focal depth of about 6.2 miles (10 km). The Istanbul-based Kandilli Seismology Institute estimated the magnitude at 5.1, with an epicenter near the town of Cat in Erzurum province. The earthquake occurred in an area north of the Northern Anatolian fault zone (NAFZ), a major strike slip fault that has generated most of the large earthquakes in Turkey. Tectonically, this area is the locus of collision between three continental plates, the Arabic plate in the south, the Eurasia plate in the north, and the Anatolian sub-plate in the west. The northward motion of the Arabian plate relative to Eurasia caused the westward escape of the Anatolian sub-plate. The NAFZ is the most prominent tectonic feature in the region and the largest strike slip fault in the world. The NAFZ merges with the East Anatolian fault zone (EAFZ) and the Bitlis suture zone in this area to form a triple junction in eastern Turkey. The NAFZ and the EAFZ define most of the earthquake activity in Turkey. The current event is located in this complex triple junction zone where deformation and seismicity are rather diffuse. There is a series of conjugate strike slip faults off these major plate boundary faults that are seismically very active. The current event occurred along one such strike-slip fault north of the NAFZ. The May 2003 M 6.4 Bingol earthquake occurred about 62 miles (100 km) southwest of the this event and in a similar tectonic environment along a NW striking strike-slip fault. During the last century, Turkey has suffered from a number of large magnitude earthquakes. However, the majority of these earthquakes, such as the devastating Izmit earthquake in 1999, happened on North Anatolian fault zone (NAFZ). At least nine people were reported killed and at least forty injuries have been reported so far. There are reports of damage to homes in at least three villages. The AIR earthquake team has run the model for the Mediterranean region. Insured losses are expected to be minimal.

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Posting Date: March 26, 2004, 10:00:00 AM