HR: 0800h
AN: T51C-0688    [Abstracts]
TI: The North Anatolian Fault Zone in the broader Istanbul/Marmara region: Monitoring a ‘seismic gap'
AU: * Bohnhoff, M
EM: bohnhoff@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Bulut, F
EM: bulut@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Aktar, M
EM: aktar@boun.edu.tr
AF: Kandilli Observatory and Earthquake Research Institute, Cengelköy, Istanbul, 34680, Turkey
AU: Childs, D M
EM: dean@boun.edu.tr
AF: Kandilli Observatory and Earthquake Research Institute, Cengelköy, Istanbul, 34680, Turkey
AU: Dresen, G
EM: dre@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AB: The North Anatolian Fault Zone (NAFZ) in Turkey represents an about 1600 km long plate boundary that slips at an average rate of 20-30 mm/yr separating the westward moving Anatolian block in the South from Eurasia in the North. The 1999 M>7 Izmit and Düzce earthquakes represent the latest of a series of westward migrating mainshocks along the NAFZ starting near Erzincan, Eastern Anatolia, in 1939. The western termination of the Izmit rupture is located in the eastern Marmara Sea near the Prince Islands in direct vicinity to the Istanbul Metropolitan region with its 14 million inhabitants. There, five seismic events with M6+ occurred since 1509. The area offshore Istanbul below the Sea of Marmara today represents the eastern end of a ~140 km long seismic gap that is believed being capable of generating two M7.1 earthquakes within the next decades or could even rupture in a large single event. To monitor the microseismic activity at a presumed ‘seismic gap' along the NAFZ south of Istanbul at low- magnitude detection threshold we deployed an amphibious seismic network surrounding the Prince Islands for a period of two months. In addition for long-term monitoring of the area a permanent seismic array (PIRES) was installed on the two outermost Prince Islands consisting of two sub-arrays of five stations each. PIRES is located within only 4 km to the main branch of the NAFZ allowing to decrease the detection threshold for microseismic activity in this area by two orders of magnitude and thus to resolve the present seismotectonic setting with unprecedented detail. First results indicate that substantial microseismicity is observed along the fault trace in distinct areas off the islands at different branches of the NAFZ allowing to image the fault structure at depth and to contribute to the discussion whether this segment of the NAFZ is creeping or locked.
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1219)
DE: 7250 Transform faults
DE: 8100 TECTONOPHYSICS
DE: 8111 Continental tectonics: strike-slip and transform
SC: Tectonophysics [T]
MN: 2007 Fall Meeting