rediff.com: Transcript of the Vinod Kumar Gaur, seismologist, Chat


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'A few earthquakes in the Himalayan belt is possible'

Bangalore, January 31, 2001, 8:00 pm IST Prof Vinod Kumar Gaur, seismologist, at the Indian Institute of Science, Bangalore, received many question on the present quake and when and where the next quake was most likely to strike.

Administrator : Mr Vinod Kumar Gaur, seismologist, will log on from Bangalore at 8 pm IST. His Chat is on the recent Gujarat earthquake, the causes and the reasons for their occurrences. Find out everything about earthquakes and the situation in Gujarat.

adi : any one there?
Prof Vinod Kumar Gaur : Hello everyone, I am here now to answer all your questions on the quake....

anilwawa : Is it true that there were indications given much earlier htat earthquakes could occur but these were not paid heed to?
Prof Vinod Kumar Gaur : I don't think that there were such clear indicationa that could have evoked a definite plan. Besides, the earthquake has been of such prodigious magnitude that much damage would have been causewd anyway in the epicentral tract.

bbb : Gaur garu, will there be more earthquakes in Gujarat? Or where is the next quake most likely?
Prof Vinod Kumar Gaur : very good question which we must attempt to answer over the next months and years. But like a good diagnosis, it would require extremely advanced diagnostics of the earth. This is possible and will hopefully be carried out by the country's scientists.

bbb : Some reports claimed that the next quake will be in Assam given the way the tectonic plates are moving. Is this true?
Prof Vinod Kumar Gaur : There is no scientific indication yet available to so definitely pinpoint the occurrence of the next earthquake. But a few very large earthquakes appear to be a distinct possibility along the Himalayan arc, North of the Gangetic Plain in this century.

pravin : can india devolop disastor management team for such large natural calamity
Prof Vinod Kumar Gaur : There is enough knowledge and potential expertise available in India to develop a disaster management strategy which actually means minimising our vulnerability to natural hazards such as earthquakes.

Prof Vinod Kumar Gaur : The Republic Day earthquake was precedede by a similarly large earthquake in 1819, which caused the earth to create a natural dam about 80 km long, not very far towards the North West of the current rupture. This earlier earthquake indeed created an 80 km long natural dam which came to be known as Allah Bundh (a dam created by God.) This can still be seen today by visitors to the area.

SPR : Hi prof Vinod. Good evening. What excatlly is the magnitude of the quake. I keep of hearing lot of different versions
Prof Vinod Kumar Gaur : The magnitude of the quake is 8.7 with an uncertainty perhaps of 0.1.

rshanx : Given that prediction of earthquakes is not precisely possible, what do you recommmend Governments, authorities should do?
Prof Vinod Kumar Gaur : I believe that on the scientific front, we should try to develop knowledge products that would yield a value for risk at any given geographical location for various time windows in the future and different levels of hazard intensity. On the technology front, we should attempt to develop modern information technology systems and computer connectivity to eventually produce an Advance Warning System. On the adminstrative front, it would be well to legislate for a National Disaster Mitigation Act as an instrument of policy and adminstrative implementation to translate the fruits of scientific knowledge and technology in reducing vulnerability of different communities at all levels.

SPR : Is there any good way of predicting the quakes? Can it be done?
Prof Vinod Kumar Gaur : Not that I know of.

Bhasker : Dear Gaur, Understand that in US, artificially created earthquakes reduces the risk of such eqs of higher magnitude. Can this be done in india too ?
Prof Vinod Kumar Gaur : An earthquake as large as the Gujarat earthquake is about 30,000 times as energetic as the ones that keep happening near Koyna. In order to release this energy in a large number of the smaller quakes would mean having a few such quakes almost every other day, ie, if it were humanly possible to so distribute its energy. Some day it maybe so when someone will have to make a social choice as to whether you would like to live with tremors , even small ones, every other day.

shaeleshmaheswari : hi gaur siris there any chance of earthquake in rajasthan
Prof Vinod Kumar Gaur : Earthquakes in continental interiors repeat after long periods (several thousand years) of quiescence. All evidences of earlier ancient earthquakes on the continent are therefore easily lost and every new quake appears as a surprise. It is difficult to say therefore if one such event will take place in Rajastan. There is however a scientific way to resolve this question and that is to detect minor puckerings of the earth's surface that often precede the final outburst by fracturing of the crust. Such small deformations of millimetre scale can now be detected by GPS geodesy but will require extensive measurements over a long period of time.

KRISHNENDU : Mr Vinod you did not answer me whether these quakes are the repititions of what once happened in Mohenjodaro & Harrappa
Prof Vinod Kumar Gaur : I don'ta have enough definite knowledge of the place of occurrence and size of Harappan earthquakes. But if you are referring to the decline of that civilisation, you should perhaps read modern texts which ascribe it to climate change.

gaurav : sir from yesterday there have been some shocks in bombay of increasing intensity are there chances of a bigger shock in baombay
Prof Vinod Kumar Gaur : Aftershocks of such a large earthquake could reach a magnitude of six which will have 800 times less energy than that of the main shock. Such large after shocks may happen any time over the next few weeks.

Prasanth : why is that even after knowing the area to be in Zone V , the IMD , did not insist on the buildings being quake proof
Prof Vinod Kumar Gaur : I don't think it is the function of the IMD to tell people to have their dwellings designed according to building codes which are freely available. Enlightened citizens who have enough resources to build pucca buildings have also the responsibility to inform themselves of the available stock of knowledge generated at considerable cost and made available to all literate people.

shyam : Mr Gaur,why is it that earthquakes cannot be predicted
Prof Vinod Kumar Gaur : Because the science of earthquakes is different from astrology!

Shivani : how prone Calcutta is to such quakes considering that fault lines are in north Bengal which is not far away from cal
Prof Vinod Kumar Gaur : Calcutta is situated on a several km thick deposit of aluvium which greatly amplifies the seismic vibrations. One should therefore try to answer your question rather urgently, but it will require a lot of study concerning quake diagnostics in the Himalayan region and of the undercarriage of Calcutta to be able to answer your question in a meaningful way.

Srinivas : Mr Gaur is it true that scientists across the world are not capable of predicting the exact time of an earthquake
Prof Vinod Kumar Gaur : Yes.

sashi : is the earthquake a direct reason of pokaran test
Prof Vinod Kumar Gaur : No.

Administrator : Mr Gaur seems to be experiencing technical problems. He'll resume shortly.

Sathish : Hello sir,What type of perventive measure we need to take to avoid this kind of quake in future..
Prof Vinod Kumar Gaur : 1) We should quantify the intensity of hazard expected at agiven geographic location for various intensities and different time windows in the future. 2. We should design appropriate building codes and have regulatory measures to enforce them for different kinds of structures. 3) We should make an inventory of vulnerable structures and make a plan for retrofitting them in order to make then resilient to an expected natural hazard. 4) We should have strict regulations for land use and urban planning and enforce them unremittingly. And finally, we should engender a consciousness for building a resilient community through education, training and continual mass communication at every level.

tetris : rshanx: We could be better prepared ourselves. Expecting a govt which has time only to hold on to power is pointless.Atleast public awareness should be increased.
Prof Vinod Kumar Gaur : The world over, it is the community preparedness and initiative as well as individual initiative that guarantees safety. Even the best Government in the world cannot be a substitute for enlightened action at the private and community level.

hkailas : Sir, Good Evening. I have read in several articles that birds and animals can detect earthquakes much earlier than human beings. Are there any research going on in this area to find out how these animals detect earthquakes and how to apply this knowledge to develop an earth quake warning system?
Prof Vinod Kumar Gaur : There have been several claims by people that unusual behaviour of animals preceded the occurrence of an earthquake. But all these claims have been made in retrospect, that is after the occurrence of the event. There is no case history of any kind that tells us of such distinctly anomolous animal behaviour which people could have interpreted as a portent of an impending earthquake and therefore it has not been possible to use it as a predictive tool.

Rao : dr. gaur, there is some confusion regardingthe intensity of the earth quake as most ofthe world centers measuring at 7.9 where as IMDmeasured it at 6.9. I also read Harsh Gupta sayingit as 7.9. In this context do youagree with IMD's assertion with theirnumber is correct. Is it not essential thait has to be measured properly fordefining zones for the future.
Prof Vinod Kumar Gaur : This will be my last answer in this chat, as we are running out of time. There are various magnitude scales which seismologists determine from different parts of the recorded wave form of ground motion. The high amplitude waves which throw seismographs off scale in the vicinity of a large earthquake make it difficult to determine this magnitude with the same reliability. The first determination of IMD was therefore presumably based on whatever parts of the seismogram could be read in the initial hours. They accordingly quoted a local magnitude called ML as 6.9. The US institutions which could see the long surface waves clearly had the advantage of being able to determine the surface wave magnitude MS soon after the event. This quoted as being 7.9. Later, with more data from South and East, IMD was able to determine the surface wave magnitude which was given as 7.8 quite close to the US value.

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