Influence of station topography and Moho depth on the mislocation vectors for the Kyrgyz Broadband Seismic Network (KNET)

Deviations of slowness and backazimuth from theoretically calculated values, the so-called mislocation vectors, are measured for the Kyrgyz Broadband Seismic Network (KNET) in the Tien Shan region. 870 events have been analysed for arrivals of P and PKP waves from all azimuths. The deviations of slowness and backazimuth show a strong trend with values up to 1 s deg(-1) for slowness values for waves arriving from the North and South and backazimuth deviations of, in some cases, more than 10 degrees for waves arriving from the East and West. Calculating the traveltime deviations of the stations for topography of the Tien Shan region and Moho depth values appropriate for this area shows that most slowness and backazimuth deviations can be reduced to very small values. The remaining mislocation vectors show no strong trends and are on average smaller than 0.2 s deg(-1) for slowness and 2 degrees for backazimuth values, which is within the error bars of these measurements. Results from array methods that rely on the knowledge of the backazimuth values show much improved resolution after the correction of the mislocation vectors which shows the importance of knowing and correcting for structures directly beneath arrays.