P Wave Velocity Structure Beneath the Baikal Rift Axis

Over 100 p wave travel times from the 1500 km en echelon Baikal Rift system are used in this study.The events range 3 to 13 degrees from Talaya, Russia (TLY) along the axis of southwest northeast trending rift in East Siberia. A Herglotz Wiechert inversion of these events resolved a crust of 6.4 km/s and a gradient in the mantle starting at 35 km depth and 7.7 km/s down to 200 km depth and 8.2 km/s. This is compatible with Gao et al,1994 cross sectional structure which cuts the rift at about 400km from TLY. The Baikal Rift hosts the deepest lake and is the most seismically active rift in the world. It is one of the few continental rifts, it separates the Siberian craton and the Syan-Baikal mobile fold belt. Two events, the March 21 1999 magnitude 5.7 earthquake 638 km from TLY and the November 13th 1995 magnitude 5.9 earthquake 863 km from TLY were modeled for there PnL wave structure using the discrete wavenumber method and the Harvard CMT solutions with adjusted depths from p-pP times. The PnL signals match well. A genetic algorithm will used to perturb the velocity structure and compare to a selection of the events between 3 and 13 degrees many will require moment tensor solutions.