The Ar-Hotol surface rupture along the Khovd fault (Mongolian Altay)

We present a 1:200,000 scale map of the Ar-Hotol surface rupture along the Khovd fault (Mongolian Altay), presumed to be the expression of the 1761 CE Mw similar to 7.8 Great Mongol earthquake. The detailed mapping combines airborne and terrestrial imaging and topographic techniques (Sentinel-2, Pleiades, TanDEM-X, UAV and TLS) to quantify right-lateral and vertical offsets ranging from similar to 1 m to similar to 4 km over a length of 238 km. The smaller offsets document the deformation associated with the last surface-rupturing earthquake that affects several Bronze to Iron Age burial mounds. Their analysis yields a robust segmentation model comprising 6 segments of 20 to 51 km in length, a maximum co-seismic slip value of 4.8 m +/- 0.5 m located near the center of the rupture. Our observations precise the varying kinematics along strike, bring new evidence of repeated faulting and confirm a Mw of 7.8 +/- 0.3.