The gravity field and deep tectonics of the Ruykyu T-A-BA system

This paper reports on our research on the gravity data around the Ryukyu T-A-BA system, and presents the results obtained and the calculation methods, such as, Moho calculation, spectrum analysis, smooth filtering, analytic extension, horizontal derivation, correlative analysis, etc. used in this study. In contrast to the information obtained from seismic profiles, the analyses show that oceanic and continental crusts demarcated by the Ryukyu T-A-BA system are very different in gravitational and tectonic characteristics. The structures in the T-A-BA region are very complicated and linearity of the gravity field and structure is very obvious. The Okinawa Trough with its two groups of fault structures in their respective NW and NNE strikes is an active neo-spreading back are basin whose development and evolution is greatly influenced by faulting.