Abstract:Velocity estimation by inversion of real seismic data has its intrinsic defect such as acquisition geometry, low signal to noise ratio. In this paper, we discuss the simultaneous joint inversion of seismic and gravity data, which minimizes the combination of single-domain objective functions, in order to reduce the non-uniqueness of inversion and improve the accuracy of seismic velocity. To solve the limitation of petrophysical approach, geological structural constraint which expressed by cross-gradient was adopted to complement the empirical relation between velocity and density. The area under analysis is in south Taiwan strait. The identification of consistent refraction patterns becomes extremely difficult due to the presence of volcanic intrusions and high noise level. Consequently, conventional first arrival tomography can only give a poorly defined velocity model for the basement. The shipborne gravity data along this profile provides a key indicator of the sediment. We fit simultaneously both gravity and seismic datasets by finding the best velocity and density models, subject to two sets of constrains. As illustrated by the presented case, compared to using seismic data only, joint inversion could improve the velocity model, reduce the uncertainty of inversion and thus enhance the resolution of tomography.
WANG Sun,YAN Pei,LIU Shanhu. Two-Dimensional Seismic Tomography Constrained by Gravity Data:A Case Study in South Taiwan Strait[J]. jgg, 2019, 39(3): 302-306.