A Regional Seismic Travel Time Model for North America
Abstract
Monitoring seismic events at ever-lower magnitude thresholds requires the utilization of seismic stations that are close to the event. The proliferation of seismic stations across the globe results in lower seismic detection thresholds because more stations are likely to be at regional distance to an event. However, utilization of arrival time data at regional distances often results in degraded location accuracy, because large variations in regional crust and upper-mantle structure can result in large travel time prediction errors. We have completed the data compilation needed to extend RSTT tomography to North America. That effort includes integration into our database of data provided by the NEIC and picks provided by the Array Network Facility for USArray stations. The integrated data have been relocated and epicenter accuracy criteria applied. Pick outliers have been identified based on overall statistics and comparison with neighboring data. Summary rays for the Pn data (Figure 3) provide excellent ray coverage across western North America, good coverage across the eastern U.S., poor coverage across central and eastern Canada. Preliminary tomographic results use a starting model that is based on CRUST2.0. We find that modification to CRUST2.0 are needed. Nonetheless, preliminary tomographic results are consistent with known velocities for major tectonic provinces. Tests of travel-time prediction based on a validation data set (Figure7) show approximately 25% reduction in the standard deviation of residuals. 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies 316
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2010
- Accession Number
- ADA569591
Entities
People
- Abelardo L. Ramirez
- Harley M. Benz
- Michael L. Begnaud
- Michael Pasyanos
- Raymond P. Buland
- Sanford Ballard
- Stephen C. Myers
- W. S. Phillips
Organizations
- Lawrence Livermore National Laboratory