The NTIS website and supporting ordering systems are undergoing a major upgrade from 8PM on September 25th through approximately October 6. During that time, much of the functionality, including subscription and product ordering, shipping, etc., will not be available. You may call NTIS at 1-800-553-6847 or (703) 605-6000 to place an order but you should expect delayed shipment. Please do NOT include credit card numbers in any email you might send NTIS.
Documents in the NTIS Technical Reports collection are the results of federally funded research. They are directly submitted to or collected by NTIS from Federal agencies for permanent accessibility to industry, academia and the public.  Before purchasing from NTIS, you may want to check for free access from (1) the issuing organization's website; (2) the U.S. Government Printing Office's Federal Digital System website http://www.gpo.gov/fdsys; (3) the federal government Internet portal USA.gov; or (4) a web search conducted using a commercial search engine such as http://www.google.com.
Accession Number ADA568913
Title Models for Broad Area Event Identification and Yield Estimation: Multiple Coda Types.
Publication Date Sep 2011
Media Count 9p
Personal Author G. E. Randall H. E. Hartse M. L. Begnaud R. J. Stead W. S. Phillips
Abstract Models of laterally varying attenuation and site effects of regional phases and their codas are necessary to correct regional amplitudes to reveal source effects of importance to identification and yield estimation procedures. We accomplish this using 2-D amplitude tomography, incorporating absolute spectral estimates based on precise ratio techniques and moment tensor results. The spectral constraints allow calibration to absolute levels, and can be used to validate amplitude prediction models. Constraints may also be used to improve resolution in the margins of ray path coverage where source-path tradeoffs would otherwise dominate. Our recent efforts have focused on improving coda analysis in areas of low Q and blockage. We must be able to use whatever coda type appears in our records if we are to estimate Mw for MDAC purposes, or use in yield estimation studies. The Lg coda has been used the most in such studies; however low crustal Q can strip the Lg and its coda from the record, especially at long distances and high frequencies. We often observe high quality Pn and Sn coda in such cases. Pg coda is observed for close in recordings, and behaves similarly to the Lg, with strength in lower bands, but generally has limited application outside local distance ranges. We have examined coda envelopes in plate boundary regions of Asia that are known to severely attenuate Lg, picking Pn, Pg, Sn, and Lg coda manually. We then processed coda using standard methods before turning amplitude data over to a simultaneous inversion of multi-coda type and multi-band data for 2-D path effects, site effects, and the absolute transfer function. The multiple coda types improved the bandwidths of observed seismic spectra as Lg covered low frequencies, and Pn and Sn coda covered overlapping high frequency bands, with the Pn band slightly higher than the Sn band. Distances were too great to include Pg coda in this study.
Keywords Amplitude
Attenuation
Codas
Estimates
Identification
Range(Distance)
Seismology


 
Source Agency Non Paid ADAS
NTIS Subject Category 48F - Geology & Geophysics
Corporate Author Los Alamos National Lab., NM.
Document Type Technical report
Title Note Conference paper.
NTIS Issue Number 1312
Contract Number DE-AC52-06NA25396

Science and Technology Highlights

See a sampling of the latest scientific, technical and engineering information from NTIS in the NTIS Technical Reports Newsletter

Acrobat Reader Mobile    Acrobat Reader