ANISOTROPY AND SUBSURFACE STRUCTURE OF THE CALIFORNIA ALBACORE REGION USING SEISMIC INVERSE THEORY

The dynamic processes that go on our planet's surface is largely, though not completely, explained by Plate tectonic theory. The California land and offshore region contains the large strike-slip San Andreas fault network, rifting in the borderland region and the former subduction of the now extinct Farallon plate, all within relatively close vicinity, collectively making this region globally unique and invaluable to seismic research. The Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment (ALBACORE) in conjunction with the CISN network offers an array of 82 seismic land stations along with 34 Ocean Bottom Seismometers (OBS) that our team used to analyze 80 Earthquake events with the purpose of furthering our collective understanding of the regional scale, subsurface seismic anisotropy & LAB boundaries. We obtain shear wave velocities as a function of depth by the inversions of Rayleigh wave phase velocity data, with the goal of resolving significant low velocity zone structures and mineral anisotropy that may serve as proxies for plate motion. In dealing with such abundant information, it is necessary to organize informatics based on region, proximity to faults and geological features as well as age of sea floor to better discern patterns. Preliminary results have shown deep ocean regions with seismic anisotropy perpendicular to sea floor magnetic anomalies at low periods that reverses to a north-south anisotropy at higher periods, an alignment that resembles plate motion. This deep ocean, two layer model transitions into multiple layers of anisotropy in the borderlands and back into a two layer model in the land regions. Though much work is still necessary, it may be possible to begin outlining the subsurface structure and anisotropy of the California region based on the seismic evidence and inversions outlined in this project.