Article,
Analysis of the IMS location accuracy in Northern Eurasia and North America using regional and global Pn travel-time tables
Pure and Applied Geophysics, 158 (1-2): 59--77 (Feb 1, 2001)
DOI: 10.1007/PL00001167
Abstract
Joint Research Program of Seismic Calibration of the International
Monitoring System (IMS) in Northern Eurasia and North America has
been signed by the Nuclear Treaty Programs Office (NTPO), Department
of Defense USA, and the Special Monitoring Service (SMS) of the Ministry
of Defense, Russian Federation (RF). Under the Program historical
data from nuclear and large chemical explosions of known location
and shot time, together with appropriate geological and geophysical
data, has been used to derive regional Pn/P travel-time tables for
seismic event location within the lower 48 States of the USA and
the European part of the RF. These travel-time tables are up to 5useconds
faster in shields than the IASPEI91 tables, and up to 5useconds slower
in the Western USA. Relocation experiments using the regional Pn
travel-time curves and surrogate networks for the IMS network generally
improved locations for regional seismic events. The distance between
true and estimated location (mislocation) was decreased from an average
of 18.8ukm for the IASPEI91 tables to 10.1ukm for the regional Pn
travel-time tables. However, the regional travel-time table approach
has limitations caused by travel-time variations inside major tectonic
provinces and paths crossing several tectonic provinces with substantially
different crustal and upper mantle velocity structure. The RF members
of the Calibration Working Group (WG): Colonel Vyacheslav Gordon
(chairman); Dr. Prof. Marat Mamsurov, and Dr. Nikolai Vasiliev. The
US members of the WG: Dr. Anton Dainty (chairman), Dr. Douglas Baumgardt,
Mr. John Murphy, Dr. Robert North, and Dr. Vladislav Ryaboy.
