IMS Calibration in North America and Northwestern Eurasia Utilizing 3-D Crustal and Upper Mantle Velocity Models to Refine Location of Regional Seismic Events
Abstract
This work was performed within the United States/Russian Federation Joint Research Program of Seismic Calibration of the International Monitoring System (IMS) in Northern Eurasia and North America. The parties to this program are the Nuclear Treaty Programs Office (NTPO), Department of Defense (DOD), USA and the Special Monitoring Service (SMS) of the Ministry of Defense (MOD), Russian Federation. A RF/US working group (WG) has been established to coordinate the joint research program, and the current membership is given below. The main objective of the calibration effort is to improve the IMS location accuracy of the regional seismic events within North America and Northwestern Eurasia (west of the Ural Mountains) using calibration datasets exchanged between the US and RF to derive Source-Specific Station Corrections (SSSCs) from 3-D crustal and upper mantle velocity models. 3-D modeling software developed by P. Firbas was used to compute SSSCs from 3-D crustal and upper mantle models for Pn, Sn, and Pg phases within North America and for Pn within Northwestern Eurasia. We described the 3-D velocity models used for calculations of the Pn and Pg travel times at the 21st Seismic Research Symposium (Las Vegas, Nevada, 1999) and at the 2nd Workshop on IMS Location Calibration in Oslo, Norway. The 3-D velocity models for Sn-waves were calculated from the Pn model using the relationship for Vp/Vs vs. depth from the AK-135 model of Kennett et al. SSSCs were calculated for the regional phases Pn, Pg, and Sn out to distances of 20 degrees, 10 degrees, and 20 degrees, respectively, for 22 IMS stations and 4 additional stations in North America and for 26 IMS stations and 9 additional stations in Northwestern Eurasia.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2000
- Accession Number
- ADA530014
Entities
People
- Vladislav Ryaboy