Evidence for a Great Medieval Earthquake (A.D. 1100) in Central Himalaya, Nepal.
Résumé
he Himalayan orogen has produced three thrust earthquakes with moment magnitude (Mw) 7.8 to 8.5 during the past century, yet no surface ruptures associated with these great earthquakes have been documented. Here, we present paleoseismic evidence from east central Nepal that, since ~700 A.D., a single earthquake ruptured the Frontal Thrust fault at ~1100 A.D., with a surface displacement of ~17 (+5/–3) meters and a lateral extent and size that could have exceeded 240 kilometers and ~Mw 8.8, respectively. Ruptures associated with Mw <8.2 events would contribute to the frontal Himalayas folding but would stop before reaching the surface. These findings could require substantial modifications to current regional seismic hazard models.