Cheinway Hwang (National Chiao Tung University, Taiwan); Ole Andersen (DTU Space, Denmark); Mark Stewart (The University of Newcastle, Australia)

On 6th of February 2016, a destructive and deadly earthquake with a magnitude of 6.4 hit Tainan in southern Taiwan and killed over 100 people. Since then, it has become increasingly important to understand surface deformations in southwestern Taiwan and the northern South China Sea. This paper investigate how satellite altimetry can contribute to this understanding of neotectonic fields. Waveform data from multi-satellite altimetry geodetic missions (e.g., ERS-1, Geosat and Jason-1) and other repeat missions providing dense data coverage (e.g., Cryosat-2 and Altika) are retracked. The derived altimeter sea surface heights are used to model a regionally optimal marine gravity field around Taiwan. The methodologies and techniques traditionally used for local and regional gravity determination are reassessed. The modelled gravity field for the study region is compared to existing models and the latest external gravity data sets. The vertical gravity gradient field is also generated to detect potentially hidden geological features around Taiwan. It is shown that oceanic areas around Taiwan can benefit from this new and detailed altimetry-derived gravity field, especially in waters offshore eastern Taiwan.