SEISMARMARA
Type | Oceanographic cruise |
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Ship | Le Nadir |
Ship owner | Ifremer |
Dates | 11/08/2001 - 09/09/2001 |
Chief scientist(s) | HIRN Alfred, SINGH Satish , TAYMAZ Tuncay |
INSTITUT DE PHYSIQUE DU GLOBE DE PARIS - UMR 7154, UMS 3454 1 rue Jussieu 75005 Paris +33 (0)1 83 95 74 00 |
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DOI | 10.17600/1080050 |
Objective | The SEISMAMARA cruise was part of the Franco-Turkish research program on the seismic risk in the Istanbul area and in the Sea of Marmara, in response to the two destructive earthquakes that occurred in 1999 on the North Anatolian Fault along the coast of the Sea of Marmara. Through a complex system of faults, the North Anatolian Fault extends under the Sea of Marmara and controls its geological dynamics. The main objective of the SEISMARMARA cruise was to determine the deep structure of the fault system, at depths where earthquakes nucleate. Since the fault system is under the sea and has not ruptured since the 18th century, it could not be studied using the usual methods. For the study of the deep structure, we adapted the multichannel seismic reflection (MCS) method for deep penetration by developing powerful single-bubble sources, we employed the seismic refraction method using the same source recorded at land stations, and we used 37 OBS sensors at the sea bottom set out ahead of time by the Turkish ship, the MTA Sismik-1. Complementary methods were used, such as tomography based on (local) earthquakes recorded using by OBS sensors at the sea bottom, and land sensors. The observation of local earthquakes was to be radically improved by a temporary network of sensors deployed in the sea (using OBSs) and increased in density on land. These data were to provide a baseline reference which, in conjunction with a structural model, will help improve the precision of observations of future earthquakes. During the first leg, 2,000 km of MCS were performed to survey the deep structure of the region at several scales and at several depths. During the second leg, 2000 km of MCS were taken for a detailed study on the Cinarcik Basin, the eastern part of the Sea of Marmara, to better understand the depositional and deformation style of the sedimentary fill. |