kkvarma
14th March 2005, 08:04 AM
IS 'DART' THE BEST OPTION FOR INDIA? - SOME SUGGESTIONS AND COMMENTS REGARDING THE FOLLOW UP ACTIVITIES RELATING TO THE RECENT TSUNAMIS
This is dedicated to the thousands of lives that were lost by the recent tsunami and the large number of people who are still suffering under its effects.
1. We hear from news reports that tsunami warning system would be established at a coast of about Rs 125 crores. It is also mentioned that Deep-Ocean Assessment and Reporting of Tsunamis(DART) systems would be installed.
2. The major expenditure in such a warning system would be for instruments.
3. The present technology (as far as I know) is to place pressure sensors on to the deep-sea bottom. Since the height of the tsunami waves, when it travels on the sea surface at deep ocean regions could be 20 to 30 cm (always less than 1m), that too separated by several kilometres (i.e.,. very long waves ), these instruments have to be very sensitive. It is because of this difference from ordinary waves, that the normal wave measuring instruments cannot be used for knowing the movements of tsunamis on real time basis.
4. The deployment of tsunami warning pressure sensors (DART) is also expensive, requiring considerable skill. Country has to depend on foreign expertise for this. Since change of pressure caused by a change of about a few centimetres of water column is to be sensed at the deep ocean floor, these instruments would require proper maintenance. Also, the life of these sensors is said to be around two years only. Tsunamis being a very rare visitor on Indian shores, there could be laxity in maintenance or replacement over the years, rendering our efforts to become of no use when the need arises.
5. Will these instruments be able to detect all tsunamis? Perhaps not. These will sense the tsunamis only if the waves pass over this. We may not be able to put many sensors in Indian Ocean. Only possibility is to put these at sensitive locations. In this case, there is a chance that tsunamis might travel through areas where pressure sensors are not deployed and thus these waves may hit us, despite the very expensive DART. Still it could be argued that some thing is better than nothing. Yes! But only if it were not so expensive.
6. Does the pressure sensors produce false alarms? Yes this is a possibility. These sensors being very sensitive, disturbances like deep ocean biological activity, if any, sediment movements resulting in deposition of sediments on sensors etc, can produce pressure change, thus sending false alarms.
7. The point in item 6. can be perhaps be overruled based on the fact that DART sensors are working well in Pacific. It has to be noted that false alarms are received there also. Then one might say that, if those countries could live with false alarms and still be able to protect life from tsunami, why cant we? Here one has to take into consideration the difference between the regions. At those regions the frequency of real tsunami occurrence is very high compared to that on our shores. Therefore, the false alarms would become some kind of drills so that preparedness would be robust, when the real tsunami arrives. On the other hand, in our situation the tsunami occurs once in several years or once in a century. Let us assume that at least one false alarm is received (if not more) in a year. Therefore, no one would pay heed to warnings when the real one comes. The effect would be exactly opposite to that in Pacific countries and when tsunami arrives, we would possibly be least prepared because of all those false alarms.
From the above, DART does not appear to be a valid option
Now there are questions as to what has to be done now since a really big tsunami hit us? Are we to keep quiet waiting for the next one probably after several years? No, This is not what is suggested. We can possibly take actions to increase our preparedness for such an eventuality in the future. Some suggestions are given below.
1. It is essential to increase research activity on tsunamis. A research group can be formed which can study the various aspects of this phenomenon. The group has to interact with other research groups, develope necessary models, in close cooperation with Indian Ocean countries. (It would be necessary to make available the source codes also so that others can improve upon it). NIO, Goa has the necessary potential to form a research unit under it.
2. Increase the number of tide gauges by several folds in the Indian Ocean countries.
3. Establish linkages with all seismic recorders in the Indian Ocean countries. If necessary, increase the number of the recorders also.
3. Combining items 1to 3, the capability for real time prediction of tsunamis has to be developed.
4. It is felt that this group must not come with a suggestion that the DART be established. This has to be viewed from the fact that these sensors have not been placed in Atlantic, although tsunamis are rare visitors there also. It must also be noted that all the Atlantic Ocean counties are rich.
5 Money saved by avoiding DART can be utilized for strengthening communication net works, creating awareness, mitigation activities necessitated by the present tsunami etc.
6. Since tsunami comes only rarely, it is necessary to remind every one about this on a continuous basis. Annual Tsunami Drills must be made mandatory in all the coastal districts. This could be like fire drills or any other contingency drills. Government machinery, local people, NGOs and interest groups must participate in this. Report must be forwarded to the Tsunami research group and after consolidation it must be forwarded to the Hon. Minister. This has been suggested because next tsunami may come to our shores after several years. Such drills are the only way in which we can remain prepared for this. Perhaps legislation may have to be passed to make the drill mandatory.
K.K.Varma
This is dedicated to the thousands of lives that were lost by the recent tsunami and the large number of people who are still suffering under its effects.
1. We hear from news reports that tsunami warning system would be established at a coast of about Rs 125 crores. It is also mentioned that Deep-Ocean Assessment and Reporting of Tsunamis(DART) systems would be installed.
2. The major expenditure in such a warning system would be for instruments.
3. The present technology (as far as I know) is to place pressure sensors on to the deep-sea bottom. Since the height of the tsunami waves, when it travels on the sea surface at deep ocean regions could be 20 to 30 cm (always less than 1m), that too separated by several kilometres (i.e.,. very long waves ), these instruments have to be very sensitive. It is because of this difference from ordinary waves, that the normal wave measuring instruments cannot be used for knowing the movements of tsunamis on real time basis.
4. The deployment of tsunami warning pressure sensors (DART) is also expensive, requiring considerable skill. Country has to depend on foreign expertise for this. Since change of pressure caused by a change of about a few centimetres of water column is to be sensed at the deep ocean floor, these instruments would require proper maintenance. Also, the life of these sensors is said to be around two years only. Tsunamis being a very rare visitor on Indian shores, there could be laxity in maintenance or replacement over the years, rendering our efforts to become of no use when the need arises.
5. Will these instruments be able to detect all tsunamis? Perhaps not. These will sense the tsunamis only if the waves pass over this. We may not be able to put many sensors in Indian Ocean. Only possibility is to put these at sensitive locations. In this case, there is a chance that tsunamis might travel through areas where pressure sensors are not deployed and thus these waves may hit us, despite the very expensive DART. Still it could be argued that some thing is better than nothing. Yes! But only if it were not so expensive.
6. Does the pressure sensors produce false alarms? Yes this is a possibility. These sensors being very sensitive, disturbances like deep ocean biological activity, if any, sediment movements resulting in deposition of sediments on sensors etc, can produce pressure change, thus sending false alarms.
7. The point in item 6. can be perhaps be overruled based on the fact that DART sensors are working well in Pacific. It has to be noted that false alarms are received there also. Then one might say that, if those countries could live with false alarms and still be able to protect life from tsunami, why cant we? Here one has to take into consideration the difference between the regions. At those regions the frequency of real tsunami occurrence is very high compared to that on our shores. Therefore, the false alarms would become some kind of drills so that preparedness would be robust, when the real tsunami arrives. On the other hand, in our situation the tsunami occurs once in several years or once in a century. Let us assume that at least one false alarm is received (if not more) in a year. Therefore, no one would pay heed to warnings when the real one comes. The effect would be exactly opposite to that in Pacific countries and when tsunami arrives, we would possibly be least prepared because of all those false alarms.
From the above, DART does not appear to be a valid option
Now there are questions as to what has to be done now since a really big tsunami hit us? Are we to keep quiet waiting for the next one probably after several years? No, This is not what is suggested. We can possibly take actions to increase our preparedness for such an eventuality in the future. Some suggestions are given below.
1. It is essential to increase research activity on tsunamis. A research group can be formed which can study the various aspects of this phenomenon. The group has to interact with other research groups, develope necessary models, in close cooperation with Indian Ocean countries. (It would be necessary to make available the source codes also so that others can improve upon it). NIO, Goa has the necessary potential to form a research unit under it.
2. Increase the number of tide gauges by several folds in the Indian Ocean countries.
3. Establish linkages with all seismic recorders in the Indian Ocean countries. If necessary, increase the number of the recorders also.
3. Combining items 1to 3, the capability for real time prediction of tsunamis has to be developed.
4. It is felt that this group must not come with a suggestion that the DART be established. This has to be viewed from the fact that these sensors have not been placed in Atlantic, although tsunamis are rare visitors there also. It must also be noted that all the Atlantic Ocean counties are rich.
5 Money saved by avoiding DART can be utilized for strengthening communication net works, creating awareness, mitigation activities necessitated by the present tsunami etc.
6. Since tsunami comes only rarely, it is necessary to remind every one about this on a continuous basis. Annual Tsunami Drills must be made mandatory in all the coastal districts. This could be like fire drills or any other contingency drills. Government machinery, local people, NGOs and interest groups must participate in this. Report must be forwarded to the Tsunami research group and after consolidation it must be forwarded to the Hon. Minister. This has been suggested because next tsunami may come to our shores after several years. Such drills are the only way in which we can remain prepared for this. Perhaps legislation may have to be passed to make the drill mandatory.
K.K.Varma