Attenuation of the LG phase in Interior Alaska

• Main Author: Marriott, Duncan A.
• Format: Thesis
• Language: English
• Published: 2002
• Subjects: Fairbanks; alaska range; Alaska
• Online Access: http://hdl.handle.net/11122/6305

Thesis (M.S.) University of Alaska Fairbanks, 2002 A simultaneous inversion of a large dataset produced robust estimates of regional attenuation for the Lg phase in interior Alaska. Data were collected from summer 1999 through summer 2001 from the Broadband Experiment Across the Alaska Range (BEAAR). Spectra calculated from this dataset were used in a nonlinear simultaneous least squares inversion to determine source factors, path effects and site amplification terms. The average regional attenuation of the Lg phase in interior Alaska was found to be: LgQ(f)=166f⁰·⁵⁸ Variation in regional attenuation has two main characteristics: variation on small spatial scales caused by small crustal heterogeneities, and increased excitation of the Lg phase along raypaths perpendicular to the strike of subduction from shallow subduction events due to the effect of the subduction zone geometry. This study also estimated stress drops, site factors, and developed a robust method of estimating seismic moment (Mo) for small events.