Abstract:Tanaka proposes spherical dislocation theories in a spherically symmetric, self-gravitating visco-elastic earth model. Gao presents user-friendly software that utilizes Tanaka’s theory, which can be used to calculate the post-seismic deformations for 30 time points after the event. Based on the work of Gao, we introduce an updated code to compute post-seismic deformations, including geoid and gravity changes caused by an arbitrary seismic source at any position, for an arbitrary time that passes after an event. The code consists of three parts. The first part is 32 set of the numerical frames of the dislocation Green function (DGF). Each frame contains a set of two-dimensional discrete numerical frames of DGFs on a symmetric earth model, according to a time point after the event. The second part is an interpolation program. Based on the above 32 sets of the numerical frame of DGF, the program can be used to calculate a set of DGF, according to an arbitrary time point after the event, as well as the mantle viscosity around the epicenter. The third part is an integration function, which performs bi-quadratic spline interpolation operations on the calculated frame of DGFs. The inputs of the integration function are the information about the seismic fault models and the observation points. After the user prepares the inputs in a file with a given format, the code will automatically compute the post-seismic deformations. Then, we calculate the co-seismic displacements caused by the 2011 Tohoku-Oki MW9.0 earthquake using the visco-elastic and full-elastic spherical dislocation theory, respectively. The two sets of results agree with each other very well. This verifies the correction of our new codes. Finally, we discuss several issues that require attention when using the code, which should be helpful for users.
FU Guangyu,LIU Tai. A User-Friendly Code for Calculating Post-Seismic Displacements and Gravity Changes on a Symmetric Viscoelastic Spherical Earth[J]. jgg, 2017, 37(7): 661-667.