M A I N   N E W S

Global team studies quake
R. Suryamurthy
Tribune News Service

New Delhi, February 21
A team of international experts has found a significant amount of liquefaction in several low-lying areas of the quake hit region of Gujarat.

The team comprising seismologists, earth scientists, civil and earthquake engineers from the Oyo Corporation of Japan (the largest geo-technical engineering and consulting company), Risk Management Solutions Inc (founded by Standard Ford University) and the RMSI of India conducted the study.

The quake measuring 6.9 on the Richter scale with its epicentre near Bhuj on Republic Day resulted in the death of about 25,000 persons. The official toll is around one lakh. The quake completely destroyed five towns and several villages.

The team of experts found a significant amount of liquefaction in the quake-hit areas. It is a phenomenon by which some water saturated sandy soils temporarily lose their bearing capabilities during a strong earthquake.

The team of experts located the trace of the fault that generated the earthquake.

“At this time, only a short segment of the fault that may extend tens of kilometres has been mapped and recorded through global positioning system. This segment is located near the village of Budarmora, 53 km east of Bhuj and 16 km west of Bhachau,” an official of the RMSI told The Tribune.

The team visited Ahmedabad, Rajkot, Bhachau, Gandhidham, Kandla, Anjar, Bhuj, Mundra and a large number of clusters located north of the road connecting Bhuj to Bhachau.

The official said the primary goal of the reconnaissance team was to gather as much information about the event before it gets destroyed over time. This includes geotechnical data like liquefaction and fault tract that will erode with time and damaged buildings that will be either retrofitted or demolished.

From the structural point of view, most of the damage and resulting deaths occurred in low and medium-rise structures. The most common damage to reinforced concrete structure with infill walls was the failure of beam-column connection due to lack of lateral force resisting system, lack of column confinement, poor construction quality and seismic detailing.

In low-rise structures, most of the damage resulted from failure of the masonry or stone walls and collapse of heavy tile roofs. This type of structures always perform poorly under quake loads, the official said.

The team suggested that many of the failures could have been avoided by providing proper lateral systems and seismic detailing.

Meanwhile, as a follow-up measure, a 25-member team of experts headed by Prof Haresh Shah of the World Seismic Safety Initiative would visit the quake hit-region shortly. The team would comprise experts in the field of earthquake hazard and risk mitigation.