Source parameters for 11 earthquakes in the Tien Shan, central Asia, determined by P and SH waveform inversion

The style and the distribution of faulting occurring today in the Tien Shan region were studied, by digitizing long-period World-Wide Standard Seismograph Network P and SH waveforms of 11 of the largest Tien Shan earthquakes between 1965 and 1982 and then using a least squares inversion routine to constrain their fault plane solutions and depths. The results of the examination indicate that north-south shortening is presently occurring in the Tien Shan, with the formation of basement uplifts flanked by moderately dipping thrust faults. The present-day tectonics of the Tien Shan seem to be analogous to those of the Rocky Mountains in Colorado, Wyoming, and Utah during the Laramide orogeny in Late Cretaceous and Early Tertiary time.