High resolution intermediate period (10-40 S) group velocity variations across central Asia. Scientific report No. 2, 15 June 1995-15 June 1996

This research is dedicated to investigating the relevance and use of intermediate period (10 - 40 s) surface wave data in problems of detection, discrimination, and the accurate location of small events using regional array data. It is focused on the analysis of data from events throughout Central and Southern Asia within 27 degrees of the Kyrgyz Telemetered Seismic Network. The main efforts during the 1 year time period covered by this report were directed to data collection and preprocessing, software development, measurements of surface wave characteristics, and constructing group velocity maps. More than 1400 wave paths for Rayleigh waves and 900 paths for Love waves have been used for this purpose. The spatial resolution of obtained maps is 250-400 km, and they exhibit many features related to local tectonic structures, unresolved by previous studies. The inversion of these maps for the 3D shear-velocity structure of the region is in progress. Such models will provide the means to enhance existing detection and location capabilities in Central and Southern Asia.