### Regional Seismic Event Location in Asia

## Station Variances

Figures 5 and 6 show P-wave residuals from seismic events located by the NEIC and ISC data centers at two stations. Means and variances are similar for data from both centers at the same station. Figures 7 and 8 show residual plots for 4 stations of the PIDC. Note that the PIDC station P-residuals have smaller variances compared to the NEIC and ISC data. P-residual propagation path correction (PPC) surfaces (next web page) are constructed by combining residuals from the ISC (years 1986-1989) and NEIC (years 1990-1996) catalogs. All seismic events were relocated using LocSAT and the ak135 velocity model. Depths were constrained to the catalog depth. Data discarded by the NEIC and ISC were held to be non-defining in LocSAT. Finally, only residuals less than 5.0 seconds in magnitude were kept. P-residuals were used only if the azmithual gap of the event location was <90°, the number of reporting stations was >=50, and depth <34km. PPC surfaces have been generated for 49 NEIC/ISC stations and 6 PIDC stations.

Introduction | Seismicity
of Asia | Station Variances | Example
PPC Surfaces

Regionalized Lop Nor Relocations |
Grid Search Locations |
Preliminary P_{n} Back-Projection Results |
Conclusions