Searching for the Trace of Great Medieval Earthquakes in Central Nepal
Large earthquakes along the Himalayan Frontal Thrust threaten densely populated regions of India and Nepal. We demonstrated that the rupture of the M ≈ 8.4, 1934, Bihar‐Nepal earthquake reached the surface along much of eastern Nepal, from at least Sir Khola to Dharan, falsifying the consensus that catastrophic 20th century Himalayan earthquakes had been blind. The 1934 event appears to have been a repeat of the great medieval earthquakes of AD 1255. Moreover, at one site, we found evidence for four to five previous large events with an average return period of 850+/‐170 years. We now focus our research on the 1344 AD earthquake, which appears to have been very destructive in Kathmandu. That earthquake postdated the 1255 event by only 89 years, which raises the question of whether a similar earthquake could not threaten Kathmandu this century. The occurrence of the 2015, 15 km deep, Gorkha earthquake implies that the Frontal Thrust in that region is now even more loaded than before. We will focus our search in regions located West of the 1934 surface rupture, with techniques similar to those that helped us identify the 1934 rupture.