3-D modeling tectonic structures beneath north-eastern Taiwan using gravity data

 

Author: Yu-Tsung Lo and HorngYuanYen

 

Abstract

The Okinawa Trough, a backarc basin, is located at the Eurasian plate and the Ryukyu Trench boundary and extends to north-eastern Taiwan. As a subduction zone, there are some complex unknown structures unsolved. In this study, we use the detail gravity data around this area to investigate the reliable subsurface density structure. First, we combine with land and marine gravity data to obtain gravity anomaly. In this study we utilize the data including land, marine and airborne gravity data. The land gravity data was measured by CPC, MOI and IES. The marine data was published by Hsu (1998). Furthermore, the observation data is sparse in mountain and marine. In order to solve the uneven distribution of measuring points, we add the airborne gravity data by Hwang (2007) to achieve observation covering better. The main processing in this study are integrating and comparing all the gravity observations included the airborne gravity measurements and surface gravity survey. Preliminary results show that the ship-borne gravity and airborne gravity are closer, but in mountains with large differences. Second, considering the geology, tomography and other constrains, we simulate the 3D density structure. According to the three-dimensional density model in this study, the Moho depth is deeper at the bottom of Ilan plain and Central Range, achieve to 45 km; It is only 35 km in northern Taiwan and western foothills.

 

References

Cheinway Hwang, Yu-Shen Hsiao, Hsuan-Chang Shih, Ming Yang, Kwo-Hwa Chen, Rene Forsberg, and Arne V. Olesen (2007) Geodetic and geophysical results from a Taiwan airborne gravity survey: Data reduction and accuracy assessment. Journal of Geophysical Research, vol. 112, B04407.

謝獻祥 (2009) 利用重力資料探討台灣及其鄰近地區之三維地下構造，國立中央大學地球物理研究所博士論文。