Tsunami and the task of educating the public

by Prof. O. A.Ileperuma

Your editorial of December 27, 2022 highlights some stark truths about the lack of efforts to educate the general public, particularly schoolchildren, on tsunamis. Authorities have to take effective action on future tsunamis hitting our shores and the major task here is to educate the general public on how to recognise a tsunami and what actions should be taken during a tsunami. The general features and the warning signs of a tsunami are a change in the tidal wave pattern where there is extensive frothing of waves hitting the shore, receding of the sea away from the land exposing fish and corals, roaring noise in the sea and the appearance of murky waters.

During the 2004 tsunami, 35,000 lives were lost and 430 schools damaged when severe waves of sea water gushed inland. Most of these lives could have been saved had we been educated enough to deal with a tsunami. During this tsunami, when the waves receded exposing the sea bottom, some people even went to the extent of grabbing the exposed land by erecting poles to demarcate their plots and when the big wave came all these people perished. This shows the poor level of education we have about tsunamis.

In contrast, Tilly Smith, a 10-year-girl from England who was at the Phuket beach in Thailand on holidays saved lives of over 100 tourists at the beach by warning them minutes before the arrival of the big wave. She was honoured by the UN and many other maritime organisations for her heroic act. When she noticed the sea receding, she immediately remembered the geography lesson she took a few weeks before and warned her parents about the impending arrival of the big wave. Even her parents were reluctant to take her advice at first but her persistence made them run to safer grounds. This was the only beach in Thailand where there were no casualties. We teach environmental science from year 1 onwards and I wonder whether the curriculum contains even a single word on tsunami. Even our undergraduates studying geography and geology or even their lecturers seem to be unaware of the characteristics of a tsunami as it became evident during discussions following the aftermath of the 2004 tsunami. Even Navy personnel in Trincomalee, where the tsunami first hit, appeared ignorant and could not identify the tsunami of 2004. Navy ships in the deep waters too did not notice or report any unusual behaviour of the ocean clearly showing that the training they have received did not include sufficient information on tsunamis. The 2004 tsunami took at least 30 minutes to travel down to areas such as Galle and had a proper warning given by the authorities in Trincomalee, a lot of lives could have been saved.

In the deep ocean, tsunami waves are inconspicuous, even though they travel at very high speeds between 500 to 1,000 km/hr. It is only when they approach the shore that they become catastrophic, reaching heights of 10 metres or more. Unlike waves generated by wind which have a period of seconds, tsunami waves in the deep ocean have a period in the order of hours. Tsunami wave crests can be as much as 650 kilometres long with a height of only 3 centimetres. Movement of water is more like a water column or block rather than a wave. Because of this feature, ships and boats in deep waters do not feel the impact of tsunami waves other than a lifting of their vessels by a few metres. This is the reason why there was not much damage to those fishing vessels in deep waters during the 2004 tsunami.

We were not at all prepared for a tsunami in 2004. The Pacific Tsunami Warning Centre based in Hawaii tried desperately to reach authorities in Sri Lanka to warn about the impending tsunami but there was no one to answer the phone because it was the day after Christmas and people were on holidays. Even those who responded did not see the gravity of this massive earthquake. Even an official of the Geological Survey and Mines Bureau claimed in a newspaper interview that they received the warning of an earthquake but did not know whether it can cause a tsunami. This again shows the lack of knowledge about tsunamis even among the professionals in this field. What better can be expected out of ordinary morsels? It is a pathetic state of affairs to see that when a massive earthquake having an energy equivalent of around 20,000 Hiroshima type atomic bombs takes place our geologists were totally ignorant of its repurcussions. This was true with other countries in the region where the response was disorganised and lethargic. Others either did not know how to interpret the warning signs, or were indifferent to them. None of the countries surrounding the Bay of Bengal issued an official warning, leaving millions of people completely at the mercy of the approaching waves.

After the 2004 tsunami, international funding organisations have supported the establishment of seismic sensors or tsunami detection buoys to detect earthquakes and tsunamis in the Indian Ocean. A typical tsunami buoy system has a pressure sensor anchored to the sea floor and a surface buoy. The sensor on the sea floor measures the change in height of the water column above by measuring associated changes in the water pressure. This water column height is communicated to the surface buoy by acoustic telemetry and then relayed via satellite to the tsunami warning centres. These buoys in the Indian ocean are controlled by India, Australia and Thailand and the data are directed to their respective meteorological stations. The National Disaster Management Centre (NDM) was established in 2005 to specifically to deal with various disasters including tsunamis and I hope that they have a 24 hour communication link with all the relevant international organisations to obtain up-to-date information on impending disasters.

Educating people about these tsunami signs including introducing these into our education curriculum is long overdue. People living near the coast who are the most vulnerable should receive priority. We should be better prepared when the next tsunami strikes. If any of these signs of a tsunami are observed, people should immediately move away from the area to a distance of at least one kilometre inland or go into a firmly constructed building climbing up to a height of at least 100 feet above the sea level.

The root cause of all problems affecting the future of mankind is the increase in world population far beyond the sustainable levels. World population reached 8 billion this year and this is about twice the number proposed by scientists as the desirable level for the number of humans inhabiting the earth. Increased fossil fuel combustion generating carbon dioxide and other greenhouse gases result in global warming and climate change. Scientists believe that global warming causes not only climate change but also geological changes causing earthquakes and volcanic eruptions. Several factors cause the creation of a tsunami waves: earthquakes, volcanoes, landslides are some of the reasons and major tsunamis are caused by earthquakes. Global warming is believed to raise the sea level by about half a metre by the year 2030 and this can increase the severity of a tsunami. Earth is supported by tectonic plates and Indonesia is at the junction of three major tectonic plates and these are the Indo-Australian, Eurasian and Pacific plates. Over 80% of the earthquakes in the world happen around the Indonesian islands. Polar ice cap melting due to global warming increases the amount of water in the oceans where it increases the pressure on these plates. It is the movement of plates past each other which brings about earthquakes and the frequency of these movements has increased over the past decade and major ones such as the one in 2004 with a strength of 9.1 on the Richter scale may happen anytime and these can definitely affect countries such as Sri Lanka. Therefore, adequate safety measures and educating all sectors of the public and school children is crucial to prevent a repetition of what happened in 2004.