The Site Response of Surface Waves

Daniel C. Bowden, & Victor C. Tsai

Submitted July 27, 2017, SCEC Contribution #7347, 2017 SCEC Annual Meeting Poster #270 (PDF)

Standard calculations of site-specific amplification assume a vertically-incident shear wave, or at least rely on the assumption that a single site-response transfer function can be observed empirically. Cases where surface waves may play an important role, such as for a large event on the San Andreas which may propagate laterally into the LA Basin, are not adequately described by the standard theory. We show that an analytic site amplification term for surface waves can be applied to 1D profiles, yielding a very different picture of expected motions for a large sedimentary basin. The difference in amplifications for different wave types is well confirmed through simple 2D simulations, and we also explore how the shape of basin edges affect the applicability of the 1D theory. For example, the shape and sharpness of basin edges control the extent to which wave conversions and focusing play a role. Additionally, site amplification maps using 1D profiles from the SCEC community velocity model are presented, to compare with observed amplifications from historic events (e.g. the 2010 El Mayor Cucapah earthquake).

Bowden, D. C., & Tsai, V. C. (2017, 07). The Site Response of Surface Waves. Poster Presentation at 2017 SCEC Annual Meeting.

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