Love Wave Group Velocity Tomography of India, Himalaya and Tibet

We present Love wave group velocity tomography calculated from broadband waveform data from Indian seismograph networks and global dataset downloaded from the IRIS-DMC. We first calculate path average 1-D fundamental mode Love wave group velocity between 10 s and 120 s period of the Transverse component of the seismograms. Then we combine these 1-D path average measurements using linear tomographic inversion, assuming great circular arc propagation, to compute 2-D group velocity map of the region at discrete periods. The region is adaptively parametrized to get high resolution at higher raypath density. We performed checker-board test to ascertain the resolution of the tomography maps and compute ray density map, raypath cross density map, and raypath orientation map to quantitatively analyze the controls of these parameters on the checker board resolution recovery. Tomographic maps at lower period show good correlation to the local geologic structures like low velocity in basins and high velocity in cratons and shields. At mid-period maps high velocity roots of cratons and low velocity in Tibet and Andaman- Burma subduction can be seen. At higher period low velocity in Tibet conforms with previous observations. We will do linear inversion of Love wave group velocity to get 3D SH wave velocity structure of the region.