US-Turkey Cooperative Research: Integrated Seismological Studies of Crust and Upper Mantle Structure in Western Anatolia

Saint Louis University, Saint Louis MO

Investigators

Abstract

0217493 Mitchell Description: This award is for support of a joint research project by Dr. Brian Mitchell, Dr. Lupei Zhu, both at the Department of Earth and Atmospheric Sciences at Saint Louis University, Saint Louis, Missouri and Dr. Nihal Akyol, Department of Geophysical Engineering at Dokuz Eylul University, Izmir, Turkey. They plan to conduct a seismological study of the western part of Turkey using groups of both high-frequency (2 Hz) and broadband seismographs. They plan to use data from the high-frequency linear array to obtain a two-dimensional structural model of the grabens and underlying rock by using teleseismsic receiver functions and employing a stacking procedure recently developed by Dr. Zhu. They will use both the linear array and regional array recordings of local earthquakes to perform a combined inversion for precise event location and a tomographic velocity model of the region, and will use data from the broadband instruments for several additional studies. Objectives of this project are to obtain models for velocity structure, including possible anisotropy, for the region, to ascertain the degree of agreement or disagreement among crust/upper mantle models of anisotropy obtained in different locations and by different methods, to infer from those models the directions and consistency of mantle flow and orientation of the crustal stress fields, and to determine the best methods for obtaining information on anisotropic structure in a region of complex structure and tectonics. Scope: The selected sites of this study are particularly suitable for the proposed research. Western Turkey is one of the most seismically active continental regions in the world, and much of it is undergoing extensive north-south extensional deformation. Because the region experiences a large number of low to medium-magnitude earthquakes it is particularly suitable for a seismological study of the continental crust in Eurasia. The region's high attenuation values have been attributed to fluid-filled cracks, which tend to cause the crust to be anisotropic. The project will lead to a better understanding of the tectonics of Western Anatolia, which comprises a portion of the Tethysides orogenic belt. The project will enhance international collaborations between scientists in the U.S. and in Turkey. It will involve a recent PhD (Zhu), as well as collaboration with and training of a female seismologist from Turkey.