Estimation of lateral variations of the Mohorovičić discontinuity using 2D modeling of receiver functions

Rumi Takedatsu, & Kim B. Olsen

Published 2016, SCEC Contribution #6137

We have used 2D finite difference modeling and azimuthally-binned receiver functions to explore whether abrupt offsets in Moho depth can be detected by one or a few closely spaced P-wave receiver functions. Our results show that 2D synthetic receiver functions generated in the immediate vicinity above a Moho depth change can provide important clues to the abruptness of the offset. In particular, diffraction of the waves impinging onto the Moho offset may generate a split Ps arrival, causing systematic variation of peak-to-peak P-Ps delay times with increasing ray parameter, depending on the location relative to the Moho offset and the incidence direction of the receiver functions. We outline an approach using a slant-stack method to constrain the location of a relatively abrupt depth change of Moho (> ~45°) using separate receiver function stacks incident from opposite directions. For a station located on the western border of the Caspian Sea in Azerbaijan (LKR) our 2D models with an ~8 km transition from a shallower Moho to the east and deeper Moho to the west generate synthetic receiver functions with features in general agreement with observations. These models, which include step- and ramp-like offsets of Moho, are in general agreement with estimates of crustal thickness from seismic data. Thus, our results suggest that characteristics in one or a few azimuthally-binned radial P-wave receiver functions in concert with a slant-stack analysis can be used to pin-point a relatively abrupt change in underlying Moho depth.

Citation
Takedatsu, R., & Olsen, K. B. (2016). Estimation of lateral variations of the Mohorovičić discontinuity using 2D modeling of receiver functions. Bulletin of the Seismological Society of America, 106(2), 337-348.