Surface Wave Tomography of the Arctic

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Abstract OPP-9818498RitzwollerLevshinLarge-scale natural-source seismology has provided very little information on the structural or tectonic history of the Arctic solid earth. The Principal Investigators will provide a significantly improved seismic model of crust and lithosphere to a minimum of 150 km below the Arctic seafloor and the surrounding high northern latitudes with a lateral resolution of about 400-500 km. A new seismic model with this resolution will: 1) provide a larger scale context to place new and emerging information from other sources; 2) fill the void between global and local information; 3) complement large-scale gravity and magnetic anomaly maps; and 4) illuminate a number of questions concerning the structure and tectonics of the Arctic. Because of the station and earthquake distribution at high northern latitudes, the structure of the Arctic crust and lithosphere is best explored with surface waves. This is an excellent time to undertake a surface wave tomographic study for four important reasons: 1) Arctic solid earth remains is one of the most poorly characterized and understood regions on Earth; 2) the number of far northern broadband digital seismic stations has grown dramatically over the past several years and most of these data are now readily accessible; 3) the methodology to use these data effectively to produce new and higher resolution surface wave dispersion maps and models of the Arctic is largely in place; and 4) the study builds on the Principal Investigators' previous and on-going of surface wave dispersion and crustal and uppermost mantle structures beneath Eurasia and other regions of the world.This project will be divided into four parts. Part 1. data acquisition, processing, clustering, and statistical analyses; Part 2. production of broadband (20 s - 150s) isotropic Rayleigh and Love wave dispersion maps (groups and phase velocity); Part 3. determination of our ability to estimate azimuthal anisotropy in Rayleigh and Love wave phase and group velocity dispersion maps; and Part 4. construction and characterization of a shear velocity model of the crust and uppermost mantle. All dispersion measurements and maps (isotropic and anisotropic) and the final shear velocity model will be available on an Arctic tomography web site. Large-scale natural-source seismology has provided very little information on the structural or tectonic history of the Arctic solid earth. The Principal Investigators will provide a significantly improved seismic model of crust and lithosphere to a minimum of 150 km below the Arctic seafloor and the surrounding high northern latitudes with a lateral resolution of about 400-500 km. A new seismic model with this resolution will: 1) provide a larger scale context to place new arid emerging information from other sources; 2) fill the void between global and local information; 3) complement large-scale gravity and magnetic anomaly maps; and 4) illuminate a number of questions concerning the structure and tectonics of the Arctic. Because of the station and earthquake distribution at high northern latitudes, the structure of the Arctic crust and lithosphere is best explored with surface waves. This is an excellent time to undertake a surface wave tomographic study for four important reasons: 1) Arctic solid earth remains is one of the most poorly characterized and understood regions on Earth; 2) the number of far northern broadband digital seismic stations has grown dramatically over the past several years and most of these data are now readily accessible; 3) the methodology to use these data effectively to produce new and higher resolution surface wave dispersion maps and models of the Arctic is largely in place; and 4) the study builds on the Principal Investigators' previous and on-going of surface wave dispersion and crustal and uppermost mantle structures beneath Eurasia and other regions of the world.This project will be divided into four parts. Part 1. data acquisition, processing, clustering, and statistical analyses; Part 2. production of broadband (20 s - 150s) isotropic Rayleigh and Love wave dispersion maps (groups and phase velocity); Part 3. determination of our ability to estimate azimuthal anisotropy in Rayleigh and Love wave phase and group velocity dispersion maps; and Part 4. construction and characterization of a shear velocity model of the crust and uppermost mantle. All dispersion measurements and maps (isotropic and anisotropic) and final shear velocity model will be available on an Arctic tomography web site.