Bihar Earthquake – India – January 15, 1934

This magnitude 8.1 earthquake ruptured the earth for a distance of 1,200 miles and killed 12,000 people.

The 1934 Bihar-Nepal earthquake had a magnitude of 8.1 and caused 12,000 deaths in Nepal and India combined. The epicenter of the earthquake was in Nepal six miles south of Mt. Everest. It was the worst that ever occurred in that country. Its rupture length was estimated to be 1,200 miles. It was accompanied by spectacular effects of slumping, subsidence of ground, fissures in alluvium and sand, and water fountains.

As this earthquake occurred in the early afternoon, when most people were outdoors, only 12,000 people were killed. Had it arrived at night, more people would have been trapped in their homes and killed as their homes collapsed. Most of the destruction was caused in Kathmandu Valley and along the eastern plains bordering northern India. More than 80,000 houses were damaged.

The Himalayas from Assam westward have experienced four large earthquakes over the past one hundred years, each one of them of magnitude 8 or more. There is evidence that even larger events have occurred in the past, and geodetic and seismic monitoring show that stress is accumulating now. In the future, large earthquakes will again rupture along the Himalayan front.

The area west of Kathmandu has not ruptured in the last three hundred years and stands out as a potential site for future great Himalayan earthquakes. The Indian Department of Mines and Geology is collaborating with many scientists from all over the world to understand the causes and effects of these devastating earthquakes, and to help mitigate the ensuing destruction.

About two hundred million years ago an ocean separated India from the rest of Eurasia. This sea was gradually consumed through the subduction of the oceanic floor beneath Tibet. Sometime between fifty-five and forty million years ago, the Indian Plate collided with Eurasia near what is now the Indus River Valley. Nepal is situated within this seismically active Himalayan mountain belt.

The continuing northward motion of India at the rate of about four centimeters per year has created wide-spread deformation, giving rise to the world’s highest mountains. Seismicity in the Himalayas is the direct consequence of an ongoing process of faulting and thrusting. Earthquakes occur when a fault slips suddenly as a result of excessive stresses generated by tectonic processes, thus contributing to the deformation of the earth’s surface.

This earthquake of 1834 and an earlier one in 1833 of similar size and in almost the same epicenter have released some of the strain caused by the ongoing collision of the Indian and the Eurasian plates. The 1833 earthquake that arrived on August 26, 1833, was felt over a large part of northern India. It shook an area half a million square miles in extent in Nepal and Tibet. Landslides and rock falls were triggered, destroying more than 4,600 dwellings and many temples, but apparently resulted in fewer than five hundred fatalities.

It is certain that the loss of life would have been far more severe had not the main shock been preceded by two large foreshocks five hours before the main shock so that people went outdoors in alarm. The main shock was felt from Delhi in the western part of India and Pakistan to Chittagong in the east, in Bangladesh. Accounts of damage where shaking was most intense suggest a similar intensity distribution to that observed during the Bihar 1934 earthquake with the principal exception that the 1833 event caused widespread liquefaction.

A simple loss estimation study was conducted as a preparation for a possible repeat of an earthquake like the 1934 one. Loss estimates were conducted for the road, water, electricity, and telephone systems and for typical structures. In addition, possible death and injury figures were estimated by looking at statistics from previous comparable earthquakes in other parts of the world. Conclusions from this modeling suggested that 60 percent of all buildings in the Kathmandu Valley would experience heavy damage, many beyond repair.

Almost half of the bridges in the valley would be impassible, and 10 percent of all paved roads would have moderate damage, such as deep cracks or subsidence. Nepal’s only international airport would be inaccessible. Ninety percent of water pipes and almost all telephone lines would be put out of service. Half of all electric lines would be knocked out. In the light of the increased population today, compared with 1934, the death toll would likely be 22,000 and the number of injured 25,000.