Footprints of an elusive mid‐14th century earthquake in the central Himalaya: Consilience of evidence from Nepal and India

Abstract

The timing and size of the last great earthquake in the central Himalaya continues to excite scientific controversy, despite a decade of palaeoseismological investigations. The studies along the frontal thrust in the Indian part of the central Himalaya disclose a faulting event between 14th and 15th century, and a dominant view presupposes the 1505 CE earthquake as the likely source. Here we evaluate the database along with independent inputs to determine the timing of the last faulting event on the frontal thrust of the central Himalaya. From the historical perspective, the Nepalese archives make a direct reference to a significant earthquake in 1344 CE, and the Indian sources hint at a restoration phase for the mid‐14th century monuments in the northern plains and coeval destruction to the ancient temples in the central Himalaya. Aside from the constraints generated from the earthquake proxies including liquefaction features and deformed stalagmites, the previous and currently acquired geological data from multiple trenches across the frontal thrust show that the last faulting event occurred between 13th and 14th centuries—the time interval coinciding with the 1344 CE earthquake. The episodic valley fills debris flow depositions identified in the Pokhara Valley in the east‐central Nepal provide additional constraints for the 1344 CE earthquake along with two previous ones in 1255 and 1100 CE. The consilience of multiple pieces of evidence from India and Nepal in combination with the new data inputs from two trench locales implicates the 1344 CE as the last of the medieval sequence of earthquakes. With a rupture length of ~600 km of the central Indian Himalaya and an average slip of 15 m, this earthquake is consistent with moment magnitude of Mw≥8.5. An earthquake of similar size is overdue in this part of the Himalaya, considering the long elapsed time of ≤700 years.