Large earthquakes along thrust systems transfer towards the surface large amounts of seismic slip accumulated at mid-crustal depth during centuries 1, 2, 3, 4, 5, 6, 7. Slips of 11–17 m and 14–22 m for the 19 earthquakes, respectively, compare well with the ~ 10–15 m slip deficit accumulated between the two earthquakes, suggesting that most of the deformation along the front is accommodated by surface-rupturing earthquakes. In the hanging wall, fluvial terraces associated with fault scarps were abandoned after a penultimate event that happened after the tenth century, a rupture we associate with the historic earthquake of 1255CE. Detrital charcoals radiocarbon dating reveals that the last event occurred between the seventeenth century and the post-bomb era, advocating for the 1934 earthquake as the most recent event. The Khutti Khola river cuts an 8 m-high fault scarp exposing Siwalik siltstone thrusted over recent alluvial deposits, with faults sealed by a colluvial wedge and undeformed alluvial sediments. Evidence for recent earthquakes is revealed along the frontal thrust in this region. Even though, previous studies revealed remnants of this surface rupture at the western end of the devastated zone, ruptures extent remains undocumented in its central part. Therefore, the location and existence of the Mw8.3 1934 Bihar–Nepal surface ruptures remain vividly disputed. Large earthquakes breaking the frontal faults of the Himalayan thrust system produce surface ruptures, quickly altered due to the monsoon conditions.
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