Feasibility of Estimating Parameters and Enhancing Reflections of Dipping Moho From Teleseismic P Wave Coda Autocorrelation

Abstract

AbstractTeleseismic P wave coda autocorrelation can retrieve reflections from subsurface structural boundaries, which can be used in lithospheric imaging. However, dipping structures cause difficulty in extraction of reflections and errors in depth estimation. Based on a previously proposed velocity analysis method, we formulated a method for estimating the dipping parameters and correcting the effects of dipping structures. First, we derived an arrival time formula for the PP reflection of the dipping Moho, which includes the effects of the ray parameters, dipping structures, and azimuthal distribution of available events. Second, the formula was used for move out correction and velocity analysis. Finally, by scanning the peak of the Moho energy group in the velocity spectrum, which varies with the azimuth and dip angles, a method was proposed to estimate the dipping parameters of the Moho. We referred to the scanning map as a dipping spectrum. A field data test at station NE44 revealed the prospects of the practical applications of this method. The dip angle of the Moho below the station was 3°, and exhibited an azimuth angle of 25°NE. The stacked waveform of the Moho reflection was significantly enhanced. This method was successfully applied to more stations adjacent to station NE44. Our results provide new insight on the Moho in this area, which are important for imaging and interpretation in areas that contain a dipping Moho such as plate subduction zones.