Unraveling the Seismic History of the Himalayas: Paleoseismological Insights from a Surface Rupture in Eastern Bhutan

Abstract

The Himalayas are known for large, destructive earthquakes. The study of paleoseismology in this area encounters challenges due to the sparse historical records of earthquakes and the inadequacy of paleoseismic data. Thus, investigating newly identified surface ruptures becomes essential for enhancing the earthquake catalog of this region. The seismic history was elucidated by investigating a surface rupture recently identified along the Main Frontal Thrust (MFT) in eastern Bhutan. At least three large paleo-earthquakes occurred along this fault over the past 10,000 years. The initial two events (E2‒E3) are dated back to pre-medieval times. Paleoseismological evidence recorded near our study area, one or two significant medieval earthquakes (the ~1100 or 1255 event) likely have occurred in Bhutan. The most recent event (E1) is identified as the 1714 earthquake, characterized by a surface rupture of 175 to ~290 km, a maximum coseismic slip of ~10.5 m, and estimated magnitudes 7.7–8.5.