T23E-01
Resolving High-Resolution Continental Scale 3D Crustal Structure Using Rayleigh Wave Phase Velocity and Ellipticity
Tuesday, 15 December 2015: 13:40
304 (Moscone South)
Fan-Chi Lin, University of Utah, Salt Lake City, UT, United States and Brandon Schmandt, University of New Mexico Main Campus, Albuquerque, NM, United States
Abstract:
The existence of large-scale broadband seismic arrays such as USArray across the US and the development of ambient noise and surface wave tomography have now made it possible to construct high-resolution 3D crustal models on a continental scale. In this presentation, I will briefly review how surface wave phase velocity maps can be determined across a large array using eikonal and Helmholtz tomography. Moreover, the recent use of Rayleigh wave ellipticity measurements, or Rayleigh wave H/V (horizontal to vertical) amplitude ratios, as additional constraints on crustal structure will also be discussed. In contrast to Rayleigh wave phase velocities, which are most sensitive to shear velocity structure at a depth roughly one-third of a wavelength, H/V ratios are most sensitive to impedance contrast near the surface shallower than one-sixth of a wavelength. Because of the complementary sensitivity of Rayleigh wave phase and H/V ratio measurements, a joint inversion of the two improves not only the ability to resolve shallow crustal structure but also the overall depth resolution in the crust. In this presentation, the 3D crustal model derived from USArray across the entire contiguous US will be used as an example to demonstrate the strength of the method. The ongoing effort to use the joint inversion method to constrain shallow crustal density structure will also be discussed.
