In this paper we give detailed station specifications as well as a preliminary study of the S-wave velocity structure beneath the Belbasi seismic array. The Belbasi seismic array is one of the first seismic arrays in the world; it was established in 1951 in the Belbasi suburb of the city of Ankara in central Turkey. This array has been jointly operated by the Turkish General Command (TGC) and the Air Force Technical Application Center (AFTAC) of the USA until February 2000. Recently, Bogazici University Kandilli Observatory and Earthquake Research Institute (KOERI) took over the operation of this array. In the near future, the entire array will be relocated to the town of Keskin, about 120 km east of the present location. This new array will be a primary seismic station of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO). IN addition to this short period array in Keskin, a new long-period array and one broadband station will be deployed around the city of Ankara. Despite its new location, the entire array, including broadband, short-period, and new long period stations, will still be named the Belbasi array but with the station code of BRTR.
Turkey, where the array is located, and the surrounding regions are seismically active and rapidly deforming and are characterized by high seismic wave attenuation in the crust (Lg) and uppermost mantle (Sn). The high attenuation of the regional seismic waves and the relatively sparse IMS station distribution in the region combine to lessen the detection capabilities in the area. This makes it essential that effective seismic arrays are deployed in the Middle East. Furthermore, the event location capabilities of the IMS have been selected as one of the major research priorities by the Preparatory Commission for the CTBTO. Data collected by the Belbasi array are critical to an effort to improve the accuracy and precision of IMS hypocenter locations in the Middle East. Similarly, it is important to characterize the seismic velocity structure at local and regional distances from the Belbasi array in order to eliminate some of the systematic location errors caused by lateral velocity heterogeneity. We have made preliminary estimates of this velocity heterogeneity using receiver-function waveform inversion for both station ANTO and the Belbasi array.
© 2001 Seismological Society of America.