The use of propagation path corrections to improve regional seismic event location in western China

Conference · Mon Mar 01 04:00:00 EST 1999

OSTI ID:325734

Steck, L K; Cogbill, A H; Velasco, A A

In an effort to improve the ability to locate seismic events in western China using only regional data, the authors have developed empirical propagation path corrections (PPCs) and applied such corrections using both traditional location routines as well as a nonlinear grid search method. Thus far, the authors have concentrated on corrections to observed P arrival times for shallow events using travel-time observations available from the USGS EDRs, the ISC catalogs, their own travel-tim picks from regional data, and data from other catalogs. They relocate events with the algorithm of Bratt and Bache (1988) from a region encompassing China. For individual stations having sufficient data, they produce a map of the regional travel-time residuals from all well-located teleseismic events. From these maps, interpolated PPC surfaces have been constructed using both surface fitting under tension and modified Bayesian kriging. The latter method offers the advantage of providing well-behaved interpolants, but requires that the authors have adequate error estimates associated with the travel-time residuals. To improve error estimates for kriging and event location, they separate measurement error from modeling error. The modeling error is defined as the travel-time variance of a particular model as a function of distance, while the measurement error is defined as the picking error associated with each phase. They estimate measurement errors for arrivals from the EDRs based on roundoff or truncation, and use signal-to-noise for the travel-time picks from the waveform data set.

• Research Organization: Los Alamos National Lab., Earth and Environmental Sciences Div., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 325734
• Report Number(s): LA-UR--99-3120; CONF-980920--; ON: DE99002083
• Country of Publication: United States
• Language: English

Related Subjects

35 ARMS CONTROL
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
CALCULATION METHODS
CHEMICAL EXPLOSIONS
CHINA
EARTHQUAKES
NUCLEAR EXPLOSIONS
PATTERN RECOGNITION
SEISMIC EVENTS
SEISMIC P WAVES
WAVE PROPAGATION