The 1967 Koyna Dam and Koyna Reservoir Earthquake
The Koyna Dam and the Koyna Reservoir formed by it are located about 200 kilometres south of Mumbai. The dam was built in 1962 and in-filled with water in 1963. On December 11, 1967 at 4:21am, an earthquake with an approximate magnitude of 7.0 struck the region in and around the dam. The event caused roughly 200 deaths, 2200 injuries, and destroyed enough homes to render more than 5000 people homeless.
The area was believed to be seismically stable prior to this event, and most experts are convinced that the earthquake was reservoir-induced. The concept of a reservoir-induced (or dam-induced) earthquake is the enormous pressure of the water behind the dam causes shifting in the underlying earth, eventually leading to increased seismicity.
The death toll remained low because the township of Koyna Nagar, which was closest to the epicentre, is fairly rural with low population density. Many neighbouring villages also experienced some human injury and significant building damage, but the one consolation was that the whole region was somewhat loosely populated.
Despite this token of good fortune, any loss of life is still tragic. Some of the deaths and injuries could be solely attributed to the time of the event. At 4:21 am most people were at home and in bed. Later in the day might have found some adults at work in the fields or children in school, but this pre-dawn quake killed men, women and children alike, catching them unawares.
To bring the sense of catastrophe home (or perhaps to sell newspapers), print media published a heart-wrenching photo of a young boy who lay dead in his bed (“the fatal bed”) after the collapse of his home. This type of sensationalistic reporting typifies the media focus on human drama and misery.
Approximately 80% of the houses in Koyna Nagar were reduced to rubble. Five neighbouring communities lost every single home in the village. Housing damage and destruction were scattered throughout the 50 villages, leaving some 5000 people homeless. For many of these people, their houses and the surrounding land represented their only possessions. For some, the evacuation during the emergency response phase was as devastating psychologically as the actual shaking was physically.
Bridges were destroyed and several sections of road were rendered unusable. Forty culverts were damaged. Amazingly the dam itself held and absorbed the shock, along with the underground installations of the power station it supported. The shock disrupted the power output, causing blackouts throughout the region as far as Mumbai. Many industrial establishments, primarily the textile mills, in Mumbai and Pune lay paralyzed for several days due to the power shortage.
This article contains an excerpt from the book on Community Resiliency Indicator (CRI) published by the Municipal Corporation of Greater Mumbai (MCGM).
To know more about Community Resiliency Indicator (CRI), click here.