Mapping seismic phase attenuation

Empire Innovation Professor

University at Buffalo

The estimation of high frequency wave attenuation is important for seismic hazard models, nuclear test monitoring and the imaging of the rheology of earth’s crust. The measurement of high frequency seismic wave attenuation is very challenging due to the large number of phenomena that effect seismic wave amplitudes. We are able to estimate the effective Q calculated from the high frequency seismic phases such as Sg and Lg by effectively isolating the path, site and source contributors to seismic amplitudes by using both two and reverse two station geometries that eliminate the effect of the seismic source. In order to reliably estimate shear wave Q we use a Reverse Two-station/event Method (RTM) to measure inter-station shear wave Q as a function of frequency, which theoretically eliminates the effects from the source, radiation pattern, and site response.

Furthermore, we can use the same approach to also isolate the relative site amplification as a function of frequency. These estimates can be used to understand variations in the amplification of high frequency seismic waves for a variety of different distance ranges and length scales.

In addition, we have developed a Bayesian approach to integrate different observations of seismic wave attenuation that are more extensive but nosier. This approach should allow us to include more data to create more reliable seismic attenuation and site amplification.

Eric Sandvol is an Empire Innovation Professor in the Department of Earth Sciences at University Buffalo. He is an earthquake seismologist who has conducted multiple seismic field deployments including in Myanmar, Thailand, Tibet, Turkiye and Caucasus. Professor Sandvol studies mountain building and seismic wave propagation (attenuation, scattering, anisotropy) using both observational and computational modeling.

He has studied regional seismic wave attenuation in Tibet, Middle East and mainland China in order to better understand the crustal and upper mantle structure beneath the planets largest mountain belts. He has more recently become interested in using these approached to help improve models that predict ground motions in large earthquakes.