Indian sensors slept through quake

Assessment hampered

By G.S. Mudur
  • Published 30.04.15
Villagers of a remote mountain village in Sindhupalchok in Nepal’s north try to salvage what they can from their collapsed homes. Picture by Sankarshan Thakur 

New Delhi, April 29: A network of 293 ground motion sensors located across northern, eastern and northeastern India lay crippled during Nepal's 7.9 magnitude earthquake and its aftershocks, handicapping researchers trying to assess how the quakes affected cities and towns in these regions.

No one knows how many of the 293 sensors designed to measure ground acceleration during earthquakes were actually recording data during the weekend earthquakes because funding for maintenance of the instruments was stopped in September 2014.

The Indian Institute of Technology, Roorkee, had established the network between 2005 and 2008, installing the sensors in district headquarters across northern and eastern states, including Bengal and Bihar, under a project funded by the Union science and technology ministry.

But the earth sciences ministry stopped funding the project in September last year, and informed IIT Roorkee in February this year to prepare to hand over the sensors to the National Centre for Seismology (NCS), an institution under the ministry.

"During this government takeover, someone perhaps forgot that the sensors need maintenance," said Ram Iyengar, an earthquake engineering specialist formerly with the Indian Institute of Science, Bangalore, who has earlier used similar ground motion data to prepare earthquake hazard maps.

"Academic users have been waiting to receive ground motion data during a big quake," Iyengar told The Telegraph .

The ground motion readings are critical to understanding how an earthquake might affect buildings and other structures in distant cities, whether Calcutta, Delhi or Patna. Such studies are important in planning engineering strategies to reduce the risk of damage from the ground motion.

While the NCS was supposed to take over control and maintenance of the sensors, email exchanges between researchers shared with this newspaper suggest that the NCS did not actually seek access to any of the instruments - whose batteries need to be periodically replaced - until Saturday's earthquakes in Nepal.

In March this year, a faculty member at IIT Roorkee, who was the principal investigator in charge of the ground motion network, wrote to the ministry, cautioning that the network has not been maintained for the past six months and several instruments may not be operational.

"Our country will cut a very sorry face if a big earthquake event occurs as in the present stage of the instrumentation, we may not get any strong motion record(s)," Ashok Kumar, professor of earthquake engineering at IIT Roorkee, had written in the email to the ministry on March 26 this year - a month before the weekend earthquakes.

Researchers in academic institutions across India who have been using the network from 2008 until 2014 have flooded IIT Roorkee with requests for data from the instruments since the Saturday earthquake and its aftershocks.

But IIT Roorkee itself has no access to data because when funds dried up, BSNL snapped lines supporting links to the sensors, managers of the network at IIT Roorkee wrote in an email sent on Monday evening to dozens of the network's users in academic institutions.

"It is a tragedy that earthquake engineers and seismologists of our country have been deprived of a golden opportunity of getting a vast set of strong ground motion data," the email said. IIT Roorkee will send a team to the sites of the instruments in Bengal, Bihar, and Uttar Pradesh to retrieve whatever data they can.

Senior officials of the earth sciences ministry told this newspaper that it had stopped funding IIT Roorkee's activities on the network because the network had been established as a time-bound research project whose term-of-funding would end in December 2014.

"The NCS is fully equipped to handle the instrumentation... the process of transferring the network starting in February 2015 is yet to be completed," Brijesh Bansal, a senior scientist at the ministry said. "The MOES (the ministry) is sending its team to find out the status... and take charge of the instruments," he said in an email.

The ground acceleration at any site depends not just on the magnitude of an earthquake but also on the intervening rock and the soil conditions at the site. "These measurements are crucial to understanding how the ground will behave in a specific town or a city," Iyengar said.

Structural engineers are expected to use such ground behaviour studies to determine how best to protect buildings, whether through retrofitting existing civil structures or incorporating special earthquake resistant features in new buildings or structures.