Seventh anniversary of 2004 Boxing Day tsunami:

Scientists aim to predict next big wave

By Pramod DE SILVA

The massive waves

After the tsunami in Aceh, Indonesia

Today, whenever an earthquake happens in and around Indonesia or in the Indian Ocean, the first thing that we ask is – is a tsunami coming? Only when the authorities say that a tsunami is not a possibility do we relax a bit. The spectre of a tsunami is always there in the deep recesses of our minds, only to come to the fore whenever an earthquake is reported in our region.

But seven years ago, on December 26, 2004, to be exact, we did not know any of these things. There was no warning that one of the biggest undersea quakes ever in history (magnitude 9.3 on the Richter Scale) had occurred near Sumatra, around 3,000 Km away. Later, it was revealed that the US Geological Survey had in fact warned Indian Ocean countries to be prepared for a big wave, but due to various reasons, this message never reached the vulnerable coastal communities in any of the 11 countries eventually affected by the disaster. Moreover, most people had not even heard the word 'Tsunami', a Japanese word for big harbour wave.

Disaster, as it turned out, was too mild a word to describe what happened on that fateful day. The massive tsunami generated by the undersea quake smothered the coasts of 11 Asian and African countries in a deadly embrace, snuffing out 230,000 lives and devastating property.

Sri Lanka was one of the worst affected countries, along with Indonesia, Thailand and India. Nearly 40,000 Sri Lankans, especially on the Southern and Eastern coastlines, perished. One million people were rendered homeless in Sri Lanka alone.

Seven years later, having learnt some harsh lessons from the tsunami cataclysm, we should be better prepared for a tsunami. There is an Indian Ocean-wide early warning system in place. If you travel along the coast, you can see tsunami warning towers and signs for evacuation routes.

Many coastal structures have been ‘built back better’ to face a tsunami threat. Many coastal dwellers who lost their houses have received houses built somewhat inland, but not too far away either, which still allows them to engage in coastal livelihoods such as fishing. Tsunami evacuation drills are being regularly held in 14 coastal districts.

Challenging task

Yet, warning systems are not foolproof. An orderly evacuation of a region facing an imminent tsunami is a herculean task and there might not be enough time in the end. It would be even more challenging at night.

Japan, one of the most technologically advanced nations in the world, faced an unprecedented tsunami on March 11, 2011, which left nearly 20,000 dead and triggered a nuclear disaster. The time from quake to impact of waves on shore was only around 30-40 minutes. Another major problem was that scientists underestimated the earthquake and tsunami hazards that north eastern Japan faced. In addition, many residents did not receive accurate tsunami warnings because the earthquake destroyed power networks – this cut off a large part of the population from the warning mechanism.

This shows that all countries, regardless of how developed they are in terms of early warning mechanisms, can still be vulnerable to tsunamis. And our region is now more geologically active than ever before which means that we cannot leave out the possibility of further tsunamis. The most frustrating aspect is that we still cannot predict earthquakes and tsunamis with any degree of accuracy.

But help could be on the way. Scientists at Stanford University have developed computational models of what happened in Japan’s 2011 tsunami disaster to predict when similar tsunamis might strike elsewhere. Stanford researchers ran simulations of what happened during the disaster using high-performance parallel processors at the University and in Texas.

The researchers now believe the seafloor uplift that caused the tsunami happened when seismic waves released by the massive earthquake bounced down from the seafloor and triggered the Pacific Plate beneath to slip.

According to reports, the simulations could prove helpful in pinpointing where the next big tsunami will occur. “What we found in our simulations, in certain cases, the rupture will actually stop short of the sea floor and that will lead to a smaller tsunami," explained Jeremy Kozdon, a post-doctoral research fellow at Stanford.

“In other cases we’ve been able to identify the conditions where the rupture can propagate all the way up to the seafloor, cause a large seafloor uplift, and cause a large tsunami.” Thus an accurate computer simulation could give coastal residents more time to head inland.

Better prepared

Scientists are also learning more about tsunamis and how they form, so that coastal countries could be better prepared for any eventuality. For example, scientists have revealed that the 133ft-high tsunami that hit Japan triggered by a magnitude 9.0 earthquake, was formed from two giant waves. This ‘merging tsunami’ had doubled in intensity over rugged ocean ridges, greatly increasing its destructive power when it reached land. The rare phenomenon was captured by NASA and European radar satellites able to calculate water depths down to a few centimetres.

Professor C.K. Shum of Ohio State University was quoted by news agencies as saying “we can use what we learned to make better forecasts of tsunami danger in specific coastal regions anywhere in the world, depending on the location and the mechanism of an undersea quake”.

A tsunami always leaves behind a traumatised population. We know of many families who were left with only one member. Many parents lost all their children in the Boxing Day tsunami. There are hundreds of children who have been left orphaned, having lost both parents.

Even as they come to terms with their loss, the fact remains that they survived due to a combination of survival instinct, stamina and perseverance. This wealth of experience could be a valuable input when planning for responding to a similar disaster.

This is indeed an approach the Japanese have been adapting in the wake of the March 2011 tsunami. By talking with survivors of the devastating tsunami, scientists may have a better idea as to how to help prevent fatalities from such events in the future.

To understand why the waves killed so many people, scientists interviewed 112 survivors at public evacuation shelters in six cities in Japan in April and June. The aim was to see why many did not immediately evacuate areas endangered by the tsunami.

It was revealed that a combination of frequent warnings with overestimated waves led to complacency. Ten percent of interviewees did not even think a tsunami would come. This is a good lesson for coastal residents and the authorities – take every warning seriously and do not let your guard down until the tsunami threat is deemed negative.

Enough protection

It was also disclosed that some inhabitants assumed the tsunami-resisting structures such as breakwaters would be high enough to protect them. Many interviewees also have not known how tsunamis are generated, which is also true of most residents of coastal areas in this country.

This is why the media should educate the people about tsunamis in a much broader sense, not just about the aspect of evacuation if a warning is given. Survivors could share their experiences, especially on TV and radio, so that the message is ingrained in others as well.

>Yes, the message is that a tsunami could strike anytime. The 2004 Boxing Day tsunami will always reside in our collective memory as one of the most destructive acts of nature ever. It is also etched in our psyche to the extent that the word is used generally to describe anything that overwhelms us. Browsing through news articles, I came across financial tsunami, literary tsunami, data tsunami, musical tsunami, rhino poaching tsunami and even inland tsunami – the latest term that describes very heavy flooding, as seen in Thailand recently.

Even as we mourn the victims of the 2004 Boxing Day tsunami, it pays to be prepared. If scientists can come up with a viable method for predicting tsunamis, that task will be much easier. We still cannot control Nature, but we might be able to anticipate its fury well in advance. That will be the biggest tribute we can pay to all those who lost their precious lives in Asia in 2004 and 2011.