Devastating earthquake likely in Assam before 2010

GUWAHATI, January 29: Gujarat's devastating earthquake has created alarm in Assam, which falls in one of the highest seismic zones of the country, with experts predicting the probability of an earthquake of a magnitude greater than eight on the Richter Scale at any time before 2010. Renowned environmental scientist S K Sarmah, who has conducted intensive research on the seismological trends in the Northeast, said studies on earthquake patterns of this region indicate that strain is accumulating in some parts of the region. Three earthquake clusters have appeared in the region and in one of these, the earthquake of 1988 occurred, he said. There is also "anomalous variation of compressional wave velocity ratio with time in the region" and the number of small magnitude earthquakes are increasing while larger magnitude ones are decreasing, he said. "These facts can be explained on the basis of dilatancy model of earthquake occurrence," he added. Sarmah said these facts, together with computed return periods for high magnitude earthquakes of the region and historical seismicity, tend to indicate the probability of occurrence of a high magnitude earthquake in western part of the Northeast at any time within the next few years. "Any delay in the occurrence of the earthquake will only increase its magnitude," he added. Sarmah pointed out that the type of destruction and other environmental effects may be similar to the two great earthquakes the state had experienced in 1897 and 1950. "The death toll may be more due to burgeoning population and a new hazard due to fire may be added in the urban areas," he said. An earthquake of magnitude greater than eight will destroy houses, buildings and other structures which are not built with proper design and standard areas. Man-made structures built on soft ground and hill slopes may collapse due to elevation, depression, tilting or violent shaking of the ground. Sarmah also pointed out that land may be degraded making it unsuitable for habitation and even the river Brahmaputra and its tributaries may change their course. Assam government has set up a disaster management committee with special emphasis on earthquakes with each district and sub-divisional headquarters directed to draw up measures to tackle any eventuality. The Assam government has also directed the concerned authorities to ensure the construction of earthquake resistant structures and create awareness among the people on how to be prepared and deal with any potential danger, a government spokesman said. In Northeast India, high magnitude earthquakes are generally followed by heavy floods, particularly if the quake occurs during the monsoon, Sarmah said. The devastating earthquakes of June 12, 1897 and August 15, 1950 were followed by heavy floods. The region west of 90 degrees longitude in Northeast India is regarded as high-seismic potential region and Sir Edward Gait in his book on History of Assam has mentioned the occurrence of devastating earthquakes in 1548, 1596, 1642, 1663, 1696, 1714, 1869 and 1875. During the last 100 years, earthquakes of devastating proportions in the Northeast occurred in 1897, 1918, 1930, 1950 and 1967. The earthquakes of 1897 and 1950 recorded an intensity of 8.7 on the Richter Scale.