Amplification and Attenuation across USArray using Ambient Noise Wavefront Tracking
KAUST Grant NumberOCRF-2014-CRG3-2300
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AbstractAs seismic travel-time tomography continues to be refined using data from the vast USArray dataset, it is advantageous to also exploit the amplitude information carried by seismic waves. We use ambient noise cross correlation to make observations of surface-wave amplification and attenuation at shorter periods (8 – 32 seconds) than can be observed with only traditional teleseismic earthquake sources. We show that the wavefront tracking approach of [Lin et al., 2012a] can be successfully applied to ambient noise correlations, yielding results quite similar to those from earthquake observations at periods of overlap. This consistency indicates that the wavefront tracking approach is viable for use with ambient noise correlations, despite concerns of the inhomogeneous and unknown distribution of noise sources. The resulting amplification and attenuation maps correlate well with known tectonic and crustal structure; at the shortest periods, our amplification and attenuation maps correlate well with surface geology and known sedimentary basins, while our longest period amplitudes are controlled by crustal thickness and begin to probe upper mantle materials. These amplification and attenuation observations are sensitive to crustal materials in different ways than travel-time observations and may be used to better constrain temperature or density variations. We also value them as an independent means of describing the lateral variability of observed Rayleigh-wave amplitudes without the need for 3D tomographic inversions.
CitationBowden DC, Tsai VC, Lin F-C (2017) Amplification and Attenuation Across USArray Using Ambient Noise Wavefront Tracking. Journal of Geophysical Research: Solid Earth. Available: http://dx.doi.org/10.1002/2017jb014804.
SponsorsData from USArray was downloaded from the IRIS Data Management Center at http://www.iris. edu/hq/. The velocity model of Schmandt et al.  was downloaded from IRIS at http://ds.iris.edu/ds/products/emc-us-crustvs-2015/. Amplification and attenuation maps are included as Supporting Information, and other results are available upon request to email@example.com. This work was supported by EAR-1453263 and EAR-1252191. F.-C.L. was supported by NSF grant CyberSEES-1442665 and the King Abdullah University of Science and Technology (KAUST) under award OCRF-2014-CRG3-2300.