Enhancing 3D Density and Velocity Models of Taiwan Using Sequential Inversion

Taiwan is situated at a complex plate boundary, and numerous velocity models have been published, providing significant insights into large-scale structural features. However, detailed shallow structures remain inadequately resolved. Gravity data, with its sensitivity to lateral variations in shallow regions, offers an excellent opportunity to address these limitations. This study aims to integrate gravity and seismic data through sequential inversion to develop a more precise structural model.

Seismic data will include travel-time records from the Central Weather Administration (CWA) seismic network and temporary stations deployed in mountainous areas by National Central University over the past decade, ensuring comprehensive station coverage. The seismic inversion will employ the tomoDD method, significantly improving structural resolution in regions with dense seismicity and enhancing earthquake location accuracy. The results will yield models of Vp, Vs, and Vp/Vs.

Gravity inversion will utilize free-air gravity data to resolve velocity and density variations within terrains characterized by topographic relief. By integrating terrestrial, marine, and airborne gravity data, the study ensures robust constraints on both shallow and deep structures. Wavelength analysis of Bouguer gravity anomalies will further distinguish shallow and deep residual gravity effects, elucidating their relationship with tectonic structures.

Finally, a relationship between seismic velocity and density will link the two distinct physical observations, enabling a sequential inversion that incorporates both gravity and seismic data. This approach will yield a subsurface model that aligns with both datasets. By adopting this innovative inversion strategy, the study aims to produce an improved three-dimensional velocity and density model for Taiwan.