TY - JOUR
T1 - Submarine fault scarps in the Sea of Marmara pull-apart (North Anatolian Fault)
T2 - Implications for seismic hazard in Istanbul
AU - Armijo, Rolando
AU - Pondard, Nicolas
AU - Meyer, Bertrand
AU - Ucarkus, Gulsen
AU - De Lépinay, Bernard Mercier
AU - Malavieille, Jacques
AU - Dominguez, Stéphane
AU - Gustcher, Marc André
AU - Schmidt, Sabine
AU - Beck, Christian
AU - Cagatay, Namik
AU - Cakir, Ziyadin
AU - Imren, Caner
AU - Eris, Kadir
AU - Natalin, Boris
AU - Özalaybey, Serdar
AU - Tolun, Leyla
AU - Lefévre, Iréne
AU - Seeber, Leonardo
AU - Gasperini, Luca
AU - Rangin, Claud
AU - Emre, Omer
AU - Sarikavak, Kerim
PY - 2005/6
Y1 - 2005/6
N2 - Earthquake scarps associated with recent historical events have been found on the floor of the Sea of Marmara, along the North Anatolian Fault (NAF). The MARMARASCARPS cruise using an unmanned submersible (ROV) provides direct observations to study the fine-scale morphology and geology of those scarps, their distribution, and geometry. The observations are consistent with the diversity of fault mechanisms and the fault segmentation within the north Marmara extensional step-over, between the strike-slip Ganos and Izmit faults. Smaller strike-slip segments and pull-apart basins alternate within the main step-over, commonly combining strike-slip and extension. Rapid sedimentation rates of 1-3 mm/yr appear to compete with normal faulting components of up to 6 mm/yr at the pull-apart margins. In spite of the fast sedimentation rates the submarine scarps are preserved and accumulate relief. Sets of youthful earthquake scarps extend offshore from the Ganos and Izmit faults on land into the Sea of Marmara. Our observations suggest that they correspond to the submarine ruptures of the 1999 Izmit (Mw 7.4) and the 1912 Ganos (Ms 7.4) earthquakes. While the 1999 rupture ends at the immediate eastern entrance of the extensional Cinarcik Basin, the 1912 rupture appears to have crossed the Ganos restraining bend into the Sea of Marmara floor for 60 km with a right-lateral slip of 5 m, ending in the Central Basin step-over. From the Gulf of Saros to Marmara the total 1912 rupture length is probably about 140 km, not 50 km as previously thought. The direct observations of submarine scarps in Marmara are critical to defining barriers that have arrested past earthquakes as well as defining a possible segmentation of the contemporary state of loading. Incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the NAF next to Istanbul. Coulomb stress modeling shows a zone of maximum loading with at least 4-5 m of slip deficit encompassing the strike-slip segment 70 km long between the Cinarcik and Central Basins. That segment alone would be capable of generating a largemagnitude earthquake (Mw 7.2). Other segments in Marmara appear less loaded.
AB - Earthquake scarps associated with recent historical events have been found on the floor of the Sea of Marmara, along the North Anatolian Fault (NAF). The MARMARASCARPS cruise using an unmanned submersible (ROV) provides direct observations to study the fine-scale morphology and geology of those scarps, their distribution, and geometry. The observations are consistent with the diversity of fault mechanisms and the fault segmentation within the north Marmara extensional step-over, between the strike-slip Ganos and Izmit faults. Smaller strike-slip segments and pull-apart basins alternate within the main step-over, commonly combining strike-slip and extension. Rapid sedimentation rates of 1-3 mm/yr appear to compete with normal faulting components of up to 6 mm/yr at the pull-apart margins. In spite of the fast sedimentation rates the submarine scarps are preserved and accumulate relief. Sets of youthful earthquake scarps extend offshore from the Ganos and Izmit faults on land into the Sea of Marmara. Our observations suggest that they correspond to the submarine ruptures of the 1999 Izmit (Mw 7.4) and the 1912 Ganos (Ms 7.4) earthquakes. While the 1999 rupture ends at the immediate eastern entrance of the extensional Cinarcik Basin, the 1912 rupture appears to have crossed the Ganos restraining bend into the Sea of Marmara floor for 60 km with a right-lateral slip of 5 m, ending in the Central Basin step-over. From the Gulf of Saros to Marmara the total 1912 rupture length is probably about 140 km, not 50 km as previously thought. The direct observations of submarine scarps in Marmara are critical to defining barriers that have arrested past earthquakes as well as defining a possible segmentation of the contemporary state of loading. Incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the NAF next to Istanbul. Coulomb stress modeling shows a zone of maximum loading with at least 4-5 m of slip deficit encompassing the strike-slip segment 70 km long between the Cinarcik and Central Basins. That segment alone would be capable of generating a largemagnitude earthquake (Mw 7.2). Other segments in Marmara appear less loaded.
KW - Continental deformation
KW - Earthquake scarps
KW - Istanbul
KW - Marmara
KW - Seismic hazard
KW - Submarine morphology
UR - http://www.scopus.com/inward/record.url?scp=72549092101&partnerID=8YFLogxK
U2 - 10.1029/2004GC000896
DO - 10.1029/2004GC000896
M3 - Article
AN - SCOPUS:72549092101
SN - 1525-2027
VL - 6
JO - Geochemistry, Geophysics, Geosystems
JF - Geochemistry, Geophysics, Geosystems
IS - 6
M1 - Q06009
ER -