Single-Station Backazimuth Estimation from P- and Rg-Waves at Regional Distance in the Central Appalachians
Abstract
The study examines the accuracy of single-station backazimuth measurements from polarization analysis of near regional P- and Rg-wave arrivals. The data set consists of 37 signals from mining explosions in the distance range 100 to 300 km, recorded at station BLA, Blacksburg, Virginia. The station-source backazimuth estimates derived from the three component station are compared with results derived from independent information, primarily from regional network epicenter locations. For P-wave signal/noise ratios in excess of 2.0, the mean backazimuth error of the single-station estimate is 6 degrees (for sources in the northwest quadrant) and the standard deviation is 21 degrees. Generally, only the initial (1 second or less) portion of the P-wave arrival is polarized in the source station azimuth. Off-azimuth arrivals consisting of converted and scattered energy appear early in the P coda. Emergent P-wave arrivals from the delay fired explosions, combined with steep apparent angles of incidence (averaging 22 degrees) complicate the single station, three component location problem. A subset of 27 signals featuring recognizable Rg arrivals was analyzed using a phase difference criterion. On average, the resulting backazimuth estimates are almost as reliable as those derived from the P-wave motion. Source-receiver backazimuth measurement, P-Wave polarization, Rg-Wave polarization.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 30, 1993
- Accession Number
- ADA278569
Entities
People
- J. A. Snoke
- Martin C. Chapman
- Shaosong Huang
Organizations
- Virginia Tech