Evidence for an earthquake barrier model from Mw ∼ 7.8 Kokoxili (Tibet) earthquake slip-distribution

The slip distribution of the Mw ∼ 7.8 Kokoxili (Tibet, 2001) earthquake has been measured at high resolution using optical correlation of satellite images and provides both the parallel and perpendicular components of the horizontal co-seismic slip. This reveals a variation of the horizontal slip at a scale of ∼ 20 km along-strike. Anti-correlation of slip parallel and perpendicular to the fault indicates transfer of slip from the horizontal to the vertical component at the ends of segments. These features suggest a rupture model with segments separated by strong persistent geometric barriers. The unexpected ending of the rupture south of the main fault can be explain by such a structure but bears important implications for the initiation and rupture directivity of the next earthquake.