The local earthquake tomography of Erzurum (Turkey) geothermal area

Abstract

Erzurum and its surroundings are one of the most seismically active areas in the Eastern part of Turkey, also known for its hydrothermal activity. This study is the first approach to characterize the crust using the local earthquake tomography. The earthquake source location and three-dimensional velocity structures were solved simultaneously by an iterative tomographic algorithm, LOTOS-12. Data from permanent networks consisting of 59 seismometers, which were installed by Ataturk University-Earthquake Research Center and Earthquake Department of the Disaster and Emergency Management Authority, are used to monitor the seismic activity in the Eastern Anatolia. In this paper, three-dimensional Vp and Vp/Vs characteristics of Erzurum geothermal area were investigated down to 30 km by using 1685 well-located earthquakes with 29,894 arrival times, consisting of 17,298 P wave and 12,596 S wave arrivals. We developed new high-resolution depth-cross sections through Erzurum and its surroundings to provide the subsurface geological structure of the seismogenic layers and geothermal areas. We applied various size horizontal and vertical checkerboard resolution tests to determine the quality of our inversion process. The basin models are traceable down to 3 km depth, in terms of P-wave velocity models. The higher P-wave velocity areas in surface layers are related to the metamorphic and magmatic compact materials. We reported that the low Vp and high Vp/Vs values were observed in Yedisu, Kaynarpinar, Askale, Cimenozu, Kaplica, Ovacik, Yigitler, E part of Icmeler, Koprukoy, Uzunahmet, Budakli, Soylemez, Koprukoy, Gunduzu, Karayazi, Icmesu, E part of Horasan and Kaynak regions. As an important result, these regions indicate geothermal reservoirs.