New Vulnerabilities - A&N Islands

New vulnerabilities
PANKAJ SEKHSARIA
http://www.hindu.com/mag/2007/12/23/stories/2007122350110400.htm

A changed topography in the Andaman and Nicobar Islands and increased seismic activity in the area have to be factored in for drafting appropriate disaster responses.

Photo: Pankaj Sekhsaria
Advancing sea: Forests and plantations destroyed due to subsidence in the Nicobar group of islands. December 26, 2004 is remembered primarily for the devastating tsunami that struck coasts across South and South-East Asia with unprecedented fury. The Andaman and Nicobar Islands, located close to the epicentre of the earthquake that caused the tsuna mi were also hit very badly and suffered huge damage to life and property. Official figures list 3,513 people as either dead or missing and 7,992 hectares as the paddy and plantation land that was affected. The number of boats fully damaged was 938, while the number of livestock reported to have been lost in the disaster was 1, 57,577.

The figures do tell us one important story; at the same time, however, they also hide another equally important one, albeit unintentionally. Disaggregating and looking at these numbers along the lines of the two island groups (Andamans and Nicobars) reveals a crucially important scenario that has not attracted the attention and analysis it actually deserves.

More damage in the Nicobars

Of the 3,513 people reported dead and missing, only 64 are from the Andaman group of islands; the remaining 3,449 are from the islands in the Nicobar Group. Seventy-six per cent of the agricultural and paddy land destroyed and 80 per cent of livestock loss was also reported from the Nicobars. The latest figures of houses being constructed for the tsunami affected also indicate a similar trend. 71 percent or 7,001 houses of the 9,797 being constructed are in the Nicobars

So, while the Nicobar Islands account for only 22 per cent and 12 per cent of the area and population respective of the entire chain of islands, 98 per cent of the deaths and 76 per cent of loss of agricultural land occurred here. The damage caused is inversely proportional to the area and population of the two groups and strikingly so.

Tectonic movements

While the tsunami was directly responsible for most of the damage, a more fundamental explanation of the situation in the islands lies in the earthquake that caused the tsunami. While the tectonic movements triggered by the earthquake catalysed the tsunami, they also caused a huge and permanent shift in the lay of the Andaman and Nicobar Islands. Preliminary assessments by Dr. Roger Bilham of the University of Colorado (http://cires.colorado.edu/%7ebilham/IndonesiAndaman2004_files/AndamanSRL4Mar.htm) showed that the Andaman Islands experienced an average permanent uplift of one to two metres while there was a subsidence of up to four meters in parts of the Nicobar group of islands. In a paper titled “Partial and Complete Rupture of the Indo-Andaman plate boundary” published in June 2005, Bilham and his co-authors point out that the tide gauge at Port Blair recorded an initial rise of sea level about 38 minutes after local shaking commenced on the day of the disaster. A 2005 report by the Geological Survey of India quoting eyewitness accounts indicated similarly, that the main shocks were felt in Port Blair around 0635 hrs local time on December 26, 2004. While the first influx of sea waves was noticed 15-20 minutes later, it was about two hours after the main shock (0830 hrs local time) that a third wave hit the shores with a velocity that caught citizens unaware. Other reports ( http://www.asce.org/files/pdf/tsunami/3-7.pdf ) indicate that the first wave of the tsunami in Port Blair came about 50 minutes after the initial earthquake. Three more waves with a gap of 30-35 minutes between each other are reported to have followed.

While this sequence of events has not been corroborated from developments on other islands here, it can be assumed that the pattern everywhere was the same and by implication, that the subsidence and uplift of the landmass occurred before the most powerful and damaging of the tsunami waves hit the shores of the Andaman and Nicobar Islands. The Nicobars, though spread over a smaller area and also more thinly populated, suffered much larger damages that the Andamans because of the subsidence that occurred.

Ecological changes

Surveys by ecologists and environmental researchers conducted after December 2004 provide supporting evidence. A report by Harry Andrews of the Andaman Nicobar Environment Team pointed out that huge coral reef areas totalling more than 60 sq. km along the western and northern coasts of the Middle and North Andaman Islands have been permanently exposed and destroyed. Studies in the Nicobar group of islands by the Salim Ali Centre for Ornithology and Nature (SACON), supported by the Wildlife Trust of India, revealed that the ecosystems that were badly damaged by the joint impact of the subsidence, the tsunami waves and the permanent ingress of sea water included forests along the coast line — particularly the mangroves and littoral forests. Faunal species that primarily reside in littoral forests like the Nicobari Megapode, the Giant Robber Crab and the Malayan Box Turtle were among those that were the worst hit. A survey in early 2006 by Dr. K. Sivakumar of the Wildlife Institute of India confirmed the findings of SACON. Sivakumar estimated that the post-tsunami population of the Nicobari Megapode was only 30 per cent of what it had been a decade ago.

The dominant human population in the Nicobar Islands is the Nicobari tribal community that is essentially coastal dwelling. They were therefore the most vulnerable and in the direct route of the powerful tsunami which followed the significant subsidence that had taken place on account of the earthquake. Of the 3,513 people reported dead or missing, 2,955 indeed were from this tribal community.

There is also evidence that the region where the islands are located has become even more seismically active since December 2004. Data gathered by the United States Geological Service (USGS) shows that nearly 20 earthquakes of a magnitude over M6 in addition to several hundred of lesser intensity have been recorded in the region in the last three years.

Some, like the September 12, 2007 earthquake off the Sumatra coast have been extremely powerful. This particular earthquake was of a magnitude greater than M8 on the Richter scale and led to the issuing of a tsunami warning along the Indonesian coast as well as in the Andaman and Nicobar Islands.

New factors

Increased seismic activity and increased threat because of this needs to now be made an important aspect of policy and development planning in the islands. Similarly, the change of the topography of the islands on account of the tectonic movements caused as a result of the massive earthquake of December 26, 2004 needs to be factored in, both for the ongoing relief and rehabilitation work here as also for future planning. An understanding and incorporation of these two basic aspects should be made fundamental to dealing with the present and the future of the A&N islands.

One important dimension, for instance, is the alteration along the coasts of all the islands, of the High Tide Line (HTL). Unless this is recalibrated, any management of or implementation of laws and regulations related to the coastal zone cannot be done effectively. They are in fact meaningless. The changed scenario also has direct implications on issues like land that can or cannot be allotted for reconstruction or for agriculture and plantations as also for materials and design of new buildings being constructed in the islands.

An understanding and through analysis of the changed ground situation and the new vulnerabilities would be the first step towards articulating and creating appropriate responses. Ignoring these and the implications is only an invitation to more trouble in the future with potentially disastrous consequences.