On very shaky ground
Despite the huge losses, India is yet to learn any lessons from the recent tremors in the Himalayan region, writes Alpa Sheth.Updated: Sep 26, 2011 21:28 IST
The scientific community is a worried lot. For the first time, six seismologists and a bureaucrat are on trial for manslaughter in Italy. The committee of seismologists and the bureaucrat had met just six days before the 6.3 Richter earthquake struck the historic city of L’Aquila on April 6, 2009, that killed over 300 people.
The committee had surmised that the series of small tremors were not necessarily an indicator or precursor of a large impending earthquake. Unfortunately they turned out to be terribly wrong.
The seven have since been charged with failure to adequately assess and intimate the risk of a potentially destructive earthquake to the local community. Now they face compensation claims from the kin of victims to the tune of $67 million.
On the face of it, this looks like a rather far-fetched premise. There is no known science that can predict when an earthquake will strike.
The people of L’Aquila were well aware of the seismic hazard to their city that had been virtually destroyed in 1703, killing over 5,000 people.
Accusing a committee of seismologists of manslaughter is akin to killing the messenger who this time around failed to bring in the bad news. Seismologists will become more tight-lipped, less chatty about assuaging fears of communities.
Seismologists know nothing about when seismic events will happen. All they can tell you is that within a broad range of variables based on fault activity and tectonic plates’ movement, there are some areas across the world that are seismically active or very active and could be the possible site for the next big one or smaller tremblors.
They may even be able to predict a magnitude range of an earthquake on an active fault. But they do not really know where exactly along a fault line or at what depth or when the energy would be released.
That said, the L’Aquila earthquake case should jolt seismologists in India to look at the task of evaluating seismic vulnerability with a fresh perspective. It would help the cause of seismic safety in India if seismologists were made more accountable.
The L’Aquila case is not the first time that manslaughter charges have been brought about in a natural disaster. Until now, however, it was the engineer who was charged for violation of buildings codes or sloppy construction.
In the aftermath of the 2001 Bhuj earthquake in which about 13,800 people died, structural engineers, contractors and builders involved in the construction and design of about 70 buildings in Ahmedabad that collapsed and caused deaths were charged under Indian Penal Code Section 304 — ‘culpable homicide not amounting to murder’.
The seismologist in India is divorced from the reality that his utterances will determine the level of safety of the built environment against earthquakes — and the cost of building infrastructure in the country.
He does not acknowledge that there are a lot of gaps in the information accessible to him to make credible deductions on seismicity of regions.
Historic data of earthquakes in India is not good. The seismologist is much handicapped with this lack of credible past data and needs to communicate this loudly and clearly so that the community does not live under a false sense of faith in his predictions (or the lack of them).
We only need to go back to the two post-1947 earthquakes in Maharashtra — the 6.4 Richter Koyna earthquake in 1967 that killed 200 and the 6.4 Richter Killari earthquake in 1993 that killed close to 10,000 — to understand the shockingly low level of seismic knowledge base in the country.
Both these earthquakes happened on blind faults — that is, the scientific community had no inkling of a possibility of an earthquake in these areas.
The seismic hazard map of the Bureau of Indian Standards (BIS) earthquake code (which mandates how buildings must be designed for earthquake safety) showed both these areas as areas of no earthquake hazard at the time of the events. Arguably, both these quakes were intracratonic events (movement within a part of the Earth’s crust that has survived the splitting and merging of continents) of which little is known.
Much of the seismic activity is along plate boundaries for which there is much more data available. That defence is, however, not palatable to those mourning the dead.
The BIS Earthquake Code Committee had recently formed a task force comprising well known seismologists to review the seismic zoning map of the current BIS earthquake code and prepare a new seismic hazard map. Parallel to this, the National Disaster Management Authority (NDMA) commissioned another independent committee to do the same.
The divergence in these two reports is so large as to completely confound a structural engineer who has to translate seismic hazard probability studies into real force levels for which he must design a building for it to withstand earthquakes.
Following one report will mean overestimating the seismic hazard in some regions and significantly underestimating it in others as per the second report. There is no convergence yet on which a hazard map shall be finally adopted.
Establishing seismic hazard and vulnerability maps are not purely scientific exercises. They are incontrovertibly linked with the techno-legal and socio-economic regimes that they operate within. Without recognising this aspect, the objective of earthquake safety can be lost.
Seismologists need to appreciate that their work does not conclude with the publishing of journal papers. They have to engage with engineers and other stakeholders to make their findings relevant. There is simply no place for the seismologist to sit in his ivory tower drawing graphs and maps that no one can read.
Sikkim is in a zone of high seismic hazard (Zone 4) as per the current Indian seismic code. Hence an earthquake of 6.9 Richter should have come as no surprise.
However, no warnings of unusual seismic activity were reported in the weeks prior to Sunday, August 18.
It would be interesting to study if any lessons learnt from the recent earthquakes in the Himalayan region — the 7.6 Richter 2005 Kashmir quake in which over 88,000 died; the 6.8 Richter 1999 Chamoli earthquake that killed almost 100; the 6.8 Richter Uttarkashi earthquake of 1991 that killed almost 770 — were applied in the region to improve disaster preparedness.
With the limited information available as of date, the answer seems a resounding ‘no’.
(Alpa Sheth is seismic advisor, Gujarat State Disaster Management Authority, and member, Bureau of Indian Standards Earthquake Code committee. The views expressed by the author are personal)
First Published: Sep 26, 2011 21:26 IST