Accession Number ADA568866
Title Extending Regional Seismic Travel Time (RSTT) Tomography to New Regions.
Publication Date Sep 2011
Media Count 12p
Personal Author M. E. Pasyanos M. L. Begnaud S. Ballard S. C. Myers W. S. Phillips
Abstract Lowering the global seismic detection threshold can be accomplished by introducing data recorded at regional distances. (<2000 km from the event) into the global monitoring systems. Unfortunately, introduction of regional data degrades average epicenter accuracy compared to locations constrained solely by data recorded at greater distances. Location accuracy degrades because regional seismic travel time (RSTT) prediction error is generally greater than prediction error for waves that travel to greater distances. In previous work we developed a computationally efficient method to capture the first-order effects of three-dimensional (3-D) crust and upper mantle structure on RSTTs. Previous results demonstrate that RSTT prediction accuracy is greatly improved by seismic tomography, in which model velocities are adjusted so that predicted travel times are in agreement with travel times that are based on a dataset of accurate event locations and arrival-time measurements. We have conducted RSTT tomography for the regional phases Pn, Pg, Sn, and Lg across Eurasia and for the Pn phase across North America. After tomography across Eurasia and North America, rigorous tests find that the standard devication of Pn travel time residuals is reduced from approximately 1.75 seconds (ak135 model) to approximately 1.25 seconds. Further, the median location error is reduced from approximately 15 km to 9 km for network configurations that effectively average out measurement error.
Keywords Earth mantle
Position(Location)
Predictions
Rstt(Regional seismic travel time)
Seismic detection
Seismology
Structural geology
Tomography
Travel time
Velocity


 
Source Agency Non Paid ADAS
NTIS Subject Category 48F - Geology & Geophysics
Corporate Author Lawrence Livermore National Lab., CA.
Document Type Technical report
Title Note Conference paper.
NTIS Issue Number 1312
Contract Number DE-AC52-07NA273441 DE-AC04-94AL85002

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