资源环境科技发展态势分析平台

An excavation across the Himalayan Frontal Thrust near Damak in eastern Nepal shows displacement on a fault plane dipping similar to 22 degrees has produced vertical separation across a scarp equal to 5.5m. Stratigraphic, structural, geometrical, and radiocarbon observations are interpreted to indicate that the displacement is the result of a single earthquake of 11.33.5m of dip-slip displacement that occurred 1146-1256A.D. Empirical scaling laws indicate that thrust earthquakes characterized by average displacements of this size may produce rupture lengths of 450 to >800km and moment magnitudes M-w of 8.6 to >9. Sufficient strain has accumulated along this portion of the Himalayan arc during the roughly 800years since the 1146-1256A.D. earthquake to produce another earthquake displacement of similar size.

Plain Language Summary The densely populated country of Nepal sits above the Himalayan Frontal Thrust fault. It is repeated displacements on this fault that are responsible for the uplift of the Himalaya mountains and considered capable of producing great earthquakes. Here we excavate a trench across the fault to show a great earthquake occurred 1146 -1256 AD in eastern Nepal. It has been a sufficiently long time since then that stresses have accumulated to a level capable of producing another such great earthquake.