Joint estimation by receiver function and gravity data based on thermal gravity correction and its application in Fujian province, China

The joint estimation by receiver function and gravity data is an effective method to obtain crustal thickness and V-p/V-s ratio beneath the seismic station. The introduction of gravity data could improve estimation accuracy compare to the traditional receiver function H-kappa stacking method, especially in the case of unclear crustal multiple waves. In areas of high geothermal, thermal gravity disturbance is an important component of the Bouguer gravity anomaly so that it cannot be neglected. At this point, the traditional joint estimation by receiver function and gravity data is no longer applicable. In this paper, an improved joint estimation based on thermal gravity correction is proposed to weaken the effect of thermal gravity disturbance. Furthermore, we combine Ps phase of receiver functions with gravity data to avoid errors introduced by unclear multiples. These improvements enable us to accurately estimate the crustal structure in the area of high geothermal. Synthetic tests verified the feasibility and robustness of this techniques, and provided the threshold of -10 mGal for initiating thermal gravity correction. The real data application in Fujian province, a typical area with high heat flow background, reveals that the crust thins toward coast area (about 28 km). High crustal Poisson's ratios (>0. 26) in western and southeastern Fujian indicate that crust thinning may be accompanied by underplating from mantle materials.