SEISMIC HAZARD IN THE AEGEAN AND SURROUNDING AREA BASED ON SPECTRAL ACCELERATION AMPLITUDES

Yesim Alpay Biro

(Thesis Supervisor: Mustafa Erdik)

ABSTRACT

The Aegean and the surrounding area, a well-known seismically active region, where numerous destructive earthquakes have occurred throughout the history, are analyzed for the probabilistic seismic hazard. A seismicity model is constructed describing the geographical distribution of the event sources and the distribution of magnitudes.

The degree of seismicity for the region is extracted from many records available to date. The previous study, which was performed in early 1999, is extended to include the major earthquakes in the second half of 1999 in Kocaeli and Düzce, Turkey, as well as in Athens, Greece. Furthermore, various historical data for the Greece earthquakes, which were not published prior these destructive earthquakes, are also taken into consideration. Numerous national and international catalogues, some of which refer back to 2100 BC, were considered, correlated and homogenized. In determining earthquake occurrences, the stochastic Homogeneous Poisson model is utilized. The complex tectonics in the region, which is a major debate topic among many authors, is analyzed to a great extent in order to achieve a reliable interpretation and seismic source zones are defined carefully to reflect the most up to date information.

22 seismic source zones are defined in the area, which represent the propagation and modification of strong ground motion as a function of earthquake magnitude and the distance between the source and the site of interest, that were generated by different authors are utilized to perform a rational seismic hazard analysis. Since the main concentration is on the response spectral seismic hazard mapping, the attenuation relationships concerning response spectral amplitudes are investigated. SEISRISK III is modified to accommodate for a finer solution for a larger area and is used for the seismic hazard estimation. Advanced GIS techniques are used for presenting and organizing the results on contour maps so that further studies that would involve the related material might benefit.