Site Characterization Based on Multi Mode Spatial Autocorrelation Analyses of Microtremor Data in Eastern Section of the North Anatolian Fault Zone (Turkey)

Erzincan region is considered as one of the most seismologically active locations in the world. The city is located in the conjunction of three active faults: North Anatolian, North East Anatolian and East Anatolian Fault Zones. The geology of Erzincan is formed as a pull-apart basin due to the interactions between North Anatolian Fault zone and Ovacik Faults which have created destructive earthquakes such as the 27 December 1939 (Ms=8.0) and the 13 March 1992 (Mw=6.6) events. The thick sediments underlying the city significantly amplify the ground motions and cause extensive losses. In this study, as an initial attempt to perform site characterization in the region, we employ microtremor survey technique at different fields in Erzincan. The use of microtremors is a well-known passive seismic tool to estimate the properties of sedimentary overburden. We perform inversions for a horizontally layered velocity structure based on surface wave dispersion curve analysis using the Multi-Mode Spatial Autocorrelation (MMSPAC) technique. We then present our results in the form of one dimensional velocity structure and dominant frequency obtained from the microtremor H/V spectral ratio curves at selected sites.