Plan for Seismic Location Calibration of 30 IMS Stations in Eastern Asia

摘要

In March 2000, a collaborative academic-industry research consortium comprised of five institutions started an integrated series of projects, all with the goal of improving the capability to locate seismic events based on data acquired by International Monitoring System (IMS) stations in Eastern Asia. The focus of this effort is to develop and deliver validated high- resolution travel time grids for operational use in support of the location estimates made by the International Data Centre (IDC) of the Comprehensive Test Ban Treaty Organization. These are to be used for the specified stations to locate on the order of a hundred events per day around the world. The basic approach is to use thousands of so-called 'ground truth' seismic events in Eastern Asia that have been accurately located by regional or local networks. These will be used to obtain the travel times of key seismic phases from any point in the region to any of the 30 IMS stations that are the focus of the project. These travel-times will in general be a function of distance and azimuth --- and depth. They must be determined as a continuous function of position, from the empirical discrete ground truth data; and they must be demonstrated to improve location estimates of new events, over the estimates obtained on the basis of current procedures (typically, based on the Earth model IASP91). In the first project, the Lamont-Doherty Earth Observatory of Columbia University will contribute numerous newly obtained ground truth locations in Eastern Asia whose errors are thought to be of the order of five km or better (so called GT5 events) and that are expected to be large enough for detection at IMS stations. In most cases these events are recent enough for inclusion in the Reviewed Event Bulletin of the PIDC (since 1995).