Seismic Surveillance. Nuclear Test Ban Verification
Abstract
The research can be divided into three main topics: (1) robust seismic event location schemes; (2) crustal structure mapping; and (3) teleseismic P- coda scattering analysis. New techniques are presented for fast and robust event location. In case of available arrival times from a network of seismograph network (aperture up to 10-15 deg) a variant of Geiger's method for fitting arrival times to travel time tables, gave average location errors less than 1 deg in the teleseismic distance range. In another study, the location schemes are tied to the slowness vector as easily derived from arrays and 3-component stations, namely azimuth error minimization and slowness vector summation on a sphere for N arbitrary positioned stations. Crustal structures are managed for various parts of Fennoscandia where the 3 seismic arrays NORESS, ARCESS and FINESA are sited. NORESS P-wave coda of 75 s duration from 8 teleseismic events of widely different azimuths have been examined using both array and 3C analysis techniques. Although source-end scattering could not be separated from the source pulse per se, favor the hypothesis of long source duration is supported by observed slow beam amplitude decay rates. The majority of receiver-end scattering contributions appears to be P-to-Rg conversions in both forward and backward modes from two nearby areas with pronounced/topographic reliefs. (JHD)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 26, 1990
- Accession Number
- ADA221768
Entities
People
- Bent O. Ruud
- Eystein S. Husebye
Organizations
- University of Oslo