Determination of Shear Wave Velocity Structure in the Rio Grande Rift Through Receiver Function and Surface Wave Analysis. Appendix B
Abstract
Waveform modeling of radial component receiver functions from ANMO (Albuquerque, New Mexico Observatory) for three source back azimuths (northwest, southeast, and southwest) has been performed. The receiver functions were derived through source equalization deconvolution of merged long period and short period digital three component seismograms. Derived S-wave velocity models reflect dominantly intermediate composition granitic rock in the upper crust (above 15 km depth, Vs 3.5 km/sec) and middle crust (15-25 km depth, Vs 3.5-3.7 km/sec). Lower crustal shear velocities of approximately 3.75-3.85 km/sec may be representative of intermediate-to-mafic granulite facies, possibly together with previously underplated mafic material and other precursor crustal rocks. Shear wave attenuation between about 30-34 km may indicate a lower crustal partial melt zone. A 3-to-6 km thick interval is interpreted as a partial melt zone in the upper mantle leading into lessdepleted spinel peridotite (Vs = 4.25-4.35 km/ sec) near 37 km. Inversion of EPT-ALQ interstation dispersion data for average S-wave velocity structure produces a satisfactory velocity tie to the middle and lower crust portions of the southwest back azimuth model.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1991
- Accession Number
- ADA246937
Entities
People
- Brian P. Murphy
Organizations
- University of Texas at El Paso