Attenuation of Lg waves in the New Madrid seismic zone of the central United States using the coda normalization method

摘要

Abstract Unique properties of coda waves are employed to evaluate the frequency dependent quality factor of Lg waves using the coda normalization method in the New Madrid seismic zone of the central United States. Instrument and site responses are eliminated and source functions are isolated to construct the inversion problem. For this purpose, we used 121 seismograms from 37 events with moment magnitudes, M, ranging from 2.5 to 5.2 and hypocentral distances from 120 to 440km recorded by 11 broadband stations. A singular value decomposition (SVD) algorithm is used to extract Q values from the data, while the geometric spreading exponent is assumed to be a constant. Inversion results are then fitted with a power law equation from 3 to 12Hz to derive the frequency dependent quality factor function. The final results of the analysis are Q V Lg (f)=(410±38) f 0.49±0.05 for the vertical component and Q H