Three-dimensional compressional wavespeed model, earthquake relocations, and focal mechanisms for the Parkfield, California, region, Thurber, C.; Zhang, H. J.; Waldhauser, F.; Hardebeck, J.; Michael, A.; Eberhart-Phillips, D. , Bulletin of the Seismological Society of America, Sep, Volume 96, Issue 4, p.S38-S49, (2006), Doi 10.1785/0120050825 Abstract