'Great quake overdue': A study had warned just two months ago
The 7.9 magnitude earthquake that rocked Nepal and vast part of northern India came less than two months after a team of scientists had predicted "a great earthquake" in the geographical region around the central Himalayas.india Updated: Apr 27, 2015 11:49 IST
Less than two months before the 7.9-magnitude earthquake that rocked Nepal and a vast swathe of northern India on Saturday, a team of Indian scientists had predicted "a great earthquake" in the geographical region around the central Himalayas.
"...the frontal thrust in central Himalaya may have remained seismically inactive during the last 700 years. Considering this long elapsed time, a great earthquake may be due in the region," the three scientists said in an article.
The expression "great earthquake" seemed to suggest that Saturday’s temblor could be a precursor to more devastating quakes.
The scientists made their prediction in the article “Medieval pulse of great earthquakes in the central Himalaya: Viewing past activities on the frontal thrust” that was published in the March 4 edition of the Journal of Geophysical Research-Solid Earth.
The article was jointly authored by C P Rajendran of the Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, Biju John of the National Institute of Rock Mechanics, Kolar Gold Fields, and Kusala Rajendran of the Indian Institute of Science-Bangalore.
In an abstract of the article, the authors cited historical evidence to argue their case.
They said the Himalayas had experienced three great quakes during the past century — in1934 (Nepal-Bihar), in 1950 (upper Assam) and "arguably" in 1905 (Kangra).
The authors said apart from these, historical data suggested there were damaging quakes in the central Himalayan region in 1255, 1344, 1505, 1803 and 1833, although their sources and magnitudes remain debated.
The authors said they had new evidence to show there was a great earthquake "from a trench across the base of a 13 metre high scarp near Ramnagar at the Himalayan Frontal Thrust".
The section, the authors said, exposed four south verging fault strands and a back thrust offsetting a broad spectrum of lithounits, including colluvial deposits.
"Age data suggests that the last great earthquake in the central Himalaya most likely occurred between AD 1259 and 1433. While evidence for this rupture is unmistakable, the stratigraphic clues imply an earlier event, which can most tentatively be placed between AD 1050 and 1250," the authors said.
The scientists further said if the two-earthquake scenario is realistic, then successive ruptures may have occurred at close intervals and were sourced on adjacent segments that overlapped at the trench site.
"Rupture(s) identified in the trench closely correlate with two damaging earthquakes of 1255 and 1344 reported from Nepal. The present study suggests that the frontal thrust in central Himalaya may have remained seismically inactive during the last 700 years,” the scientists said.
"Considering this long elapsed time, a great earthquake may be due in the region," the authors concluded in the abstract.
Environmentalists believe growing population pressure and degradation of the environment may have exacerbated the risks of a major earthquake manifold.