ENGINEERING GEOLOGICAL CHARACTERISTICS OF AUGUST 17, 1999 EASTERN MARMARA EARTHQUAKE AND THE RECENT SEISMO-TECTONIC SETTING OF THE REGION

The Eastern Marmara Earthquake occurred on August 17, 1999 at 03.02 a.m. (local time) with the magnitude of 7.4 on the Richter scale and the epicenter located at Golcuk about 11 kilometers south of Izmit. This earthquake broke the western segment of the North Anatolian Fault (NAF) designated as a “seismic gap” between the previous breaks, occurred in 1963 and 1967 by Cinarcik (Ms=6.3) and Adapazari (Ms=7.2) earthquakes, respectively.

Although some recent submarine seismicity studies provided some data about the locations and surface traces of the active fault at the base of Marmara Sea, the recent tectonic setting in this region is still not very well known. In this study the overall stress regime results from the motions of the plates adjacent to the major active faults of Turkey is determined on an analytical model utilizing the finite elements technique to investigate the recent seismotectonic characteristics of the Marmara Sea; and to foresee the possible magnitudes of the future earthquakes to occur in the area.

It is proposed that if a technique can be developed to enable earth scientists to clearly define the fault plane morphology (i.e., locations and sizes of asperities on the fault plane); in other words, a sort of topographic map of the fault plane down to about 20 – 30 kilometers of the earth crust; it may be possible to predict a future earthquake, in terms of its location, depth, magnitude and time, after a major earthquake occurs on a known active fault plane.