Full-waveform synthetic seismograms for evaluating seismic proxies for the lithosphere-asthenosphere boundary

The lithosphere-asthenosphere boundary (LAB) is a fundamental element of the dynamic Earth system. While various geophysical methods can provide useful proxies for imaging the LAB, including seismic studies (surface-wave inversion, receiver-function analysis, and investigation of seismic anisotropy) and magnetotelluric methods, consistent interpretations of these results remain elusive. Here, we are developing a systematic, comprehensive and realistic suite of synthetic data with the aim of benchmarking various seismological methods for imaging the LAB. Our study is based on a hypothetical regional geological model (800X800X400km) that is smoothly embedded within a standard global Earth model. The regional model extends from oceanic to thick cratonic lithosphere. Physical proper ties of the regional model (i.e. anisotropic elastic moduli, density, thermal and rheological parameters) match prescribed surface heat-flow and geoid boundary conditions and are computed using an approach based on thermodynamics, mineral physics, geochemistry, petrology, and solid-Earth geophysics. Anisotropy is incorporated into the model through both mantle-flow calculations and prescribed fossil anisotropy within cratonic lithosphere. Long-period synthetic seismograms are computed forteleseismic events using SPECFEM3DGLOBE, which provides full wave-equation modeling of seismic wave propagation incorporating phenomena such as anisotropy, attenuation and fluid-solid interfaces. To ensure a realistic (non-ideal) azimuthal distribution, the event locations are based on a subset of a one-year global catalog within the magnitude range from 6.0 to 7.0. Forward modeling of magnetotelluric response will also be under taken. The data from this study will be released as a benchmark dataset fortesting by research groups.