What Did We Learn From Indian Ocean Tsunami?

A beach in Chennai, India, is covered by water and debris following a massive tsunami that hit the region on Dec. 26, 2004. (Photo: STR/AFP/Getty Images).

Ten years after a tsunami out of the Indian Ocean devastated the coastal areas of 14 countries, killing 230,000 people and causing billions of dollars in damage, two specials take an in-depth look at the Dec. 26, 2004 disaster to explain how it happened, and what we've learned since then about how to save lives if it ever happens again.

Premiering Dec. 21 on Smithsonian Channel, "Asian Tsunami: The Deadliest Wave" incorporates survivor accounts, archive footage, CGI re-creations and interviews with scientists who discuss advances in early warning systems and the chances of a tsunami striking the Pacific Northwest. History, scientific analysis and prediction are the focus of National Geographic Channel's "The Next Mega Tsunami," which airs on the actual anniversary and precedes an encore of the disaster timeline documentary "Tsunami: Day of Destruction."

We talked to two experts — Charles Rubin Ph.D., professor of Geological Sciences at Central Washington University, who appears in "The Next Mega Tsunami," and "Deadliest Wave" expert Vasily Titov, director of the National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory, Center for Tsunami Research in Seattle — who shared their insights about the anniversary in separate interviews.

MNN: Why was the 2004 tsunami so devastating?

Vasily Titov: The 2004 Indian Ocean tsunami was generated by one of the largest earthquakes ever registered instrumentally. Only one earthquake — the 1960 Great Chile earthquake — is known to have released more energy. What made it much more devastating than the Chilean tsunami was the fact that the waves hit some of the most populated coastlines in the world, where people were absolutely unprepared, with no warning capabilities or any knowledge about a tsunami.

What don't people understand about tsunamis?

Titov: People often think that tsunami waves resemble typical ocean waves but bigger. This is a misconception. A typical ocean swell at a beach will never penetrate beyond high-tide mark. Wind waves will break on or near a beach and retreat in a matter of few seconds. A tsunami attack on a coast will look different: A tsunami may not even form a breaking front before it reaches the beach. It may start from a seemingly slow change of the normal water level, either withdrawing water offshore or flooding beyond normal coastline. However, the slow change of water level may quickly become very fast flooding that can push water very fast and far beyond the beach boundary, potentially flooding vast areas of low-lying land. A tsunami will be very persistent in pushing that water on land for tens of minutes (not seconds like during ocean swell) before withdrawing and starting the whole process again. Tsunami attacks can persist for hours at the coast with four or more waves flooding coastlines repeatedly. One does not have to be a tsunami expert to recognize a tsunami danger. If you feel an earthquake, with earth shaking continuing for more than 15-20 seconds, if you see unusual fast water level change, or hear unusual noise from the ocean, there may be a tsunami coming. Don't wait for an official warning. Acting decisively and immediately may save your life.

Charles Rubin: We now have a better understanding about large tsunamis along the Aceh coastline in Indonesia. Certainly, the local residents now know that the region is at risk for large earthquakes and tsunamis. The 2004 event was not an anomaly; these tsunamis have happened numerous times in the geologic past. We have to assume that all subduction zones can produce very large earthquakes and tsunamis. Although we cannot make short-term predictions for tsunamis, we can learn from the record of ancient tsunamis. How often do they occur, are they regularly spaced in time or do they have variations in repeat times? Understanding how the Earth works will provide an understanding on how to mitigate such damage in the future. With community engagement, we can start preparing strategies for tsunami evacuation, find safe locations for hospitals and educational facilities, assess and strengthen existing buildings, better design for new building and in the end, improve earthquake safety policies.

Professors Charles Rubin and Kerry Sieh stad inside a hole dug to expose the tsunami sediments
Professors Charles Rubin (left) and Kerry Sieh stand inside a hole dug to expose the tsunami sediments. Layers of bat guano form a boundary between each layer of tsunami sand, allowing the scientists to date each giant wave that has hit the coast in the past. George Harris/National Geographic Channels

What are the chances a tsunami of similar magnitude will happen again?

Rubin: If the past is the key to the future, we now know that the penultimate tsunami occurred in 1450. This gives us about a 550-year time between the most recent tsunami and the penultimate event. That said, we also know that in this region, tsunamis cluster in time, so the 2004 event is not a one-off tsunami. Our geologic studies suggest great variations in the repeat times between tsunamis. This tells us that the risk for future tsunamis is always present.

Titov: The chances of another tsunami like the 2004 Indian Ocean or 2011 Japan are 100 percent. Such tsunamis will happen. We don't know when and where, but we do know that they will occur. Big earthquakes of magnitude-9 or higher happen few times in a century. Virtually all big earthquakes happen under water, where oceanic plates meet continental plates near coastlines. Therefore, they will generate tsunamis. What is different today that we know about tsunamis, prediction, warnings that we didn't know in 2004? We know how to forecast tsunami flooding at coastlines while a tsunami is still propagating. Only the Pacific Ocean had a tsunami warning system before 2004. Today, we know to predict flooding with certainty, using direct observation of tsunamis, while the waves are still propagating across oceans. Virtually all coastlines of the world oceans are covered by one of the national or regional tsunami warning systems.

What have scientists learned from studies and experiments?

Rubin: We now know that there are great variations in the recurrence of tsunamis. The take-home message from all this research is that the biggest tsunamis are not evenly spaced through time. There can be long periods of quiescence, but you can also get major events that are separated by just a few decades.

Titov: We know much better how tsunamis impact coastlines. Lab experiments and field surveys after tsunamis provide critical data to test, calibrate and verify models that are used for tsunami forecasts. Controlled experiments in laboratories are essential for understanding forecasting capabilities. In one set of experiments, small-scale tsunamis were generated in a laboratory basin with an island in the middle that helped to understand why the lee side of islands are often damaged even more that the front side where the tsunami arrives first.

What systems and innovations are now available that can help save lives? What's in the works for the future?

Titov: Tsunami warning systems cover all coastlines of world oceans today. We have a global observation system that will detect a tsunami everywhere. We have operational tsunami flooding forecast capabilities that will predict tsunami impact while the wave is still propagating across oceans. Preparedness for such an event is also much improved.

Rubin: Real-time earthquake monitoring instrumentation will help mitigate damage from future earthquakes, such as automatic switching for turning off elevators, stopping trains, etc. In addition, understanding the geologic record of past earthquakes will help us design safer buildings. Insights gained from the Andaman-Aceh and Tohoku earthquake has helped scientists re-evaluate how major faults are segmented. Here, we might modify hazard analyses for the western United States that will improve earthquake scenario modeling, building codes, and public warnings about tsunami threats.

The Cascadia trench along the Pacific coast of the United States
The Cascadia trench is highlighted in red along the Pacific Coast of the United States and Canada. The trench zone is capable of producing strong earthquakes that can in turn generate powerful tsunamis. Smithsonian Channel/ITN Productions

The Cascadia trench is highlighted in red along the Pacific Coast of the United States and Canada. The trench zone is capable of producing strong earthquakes that can in turn generate powerful tsunamis. (Image: Smithsonian Channel/ITN Productions)

What areas of the U.S. are most vulnerable? Are they prepared for a tsunami? What can people who live in these areas do?

Titov: On the Atlantic side, tsunamis happen less often than in the Pacific, however the population density on the East Coast is much higher, therefore tsunami risk is still substantial.

Rubin: The Pacific Northwest is vulnerable for large earthquakes and tsunamis. Here, the hazards are present along the coast of Washington, Oregon and northern California. Cities such as Seattle are at risk with nearby faults that could produce ground shaking and a tsunami. Based on geologic studies of past great earthquakes and tsunamis, local communities have migration strategies along the coast that include evacuation routes, better building designs, and up to date earthquake safety policies.

What do you hope viewers take away from the special?

Titov: I hope this special will be another reminder for all viewers about tsunami danger and another educational opportunity for everyone. I hope it will make us all more informed about tsunamis. Education can save lives. During the Indian Ocean tsunami, a 10-year British girl who learned about tsunamis in geography class saved less-informed grown-ups at a beach in Thailand.

Rubin: Understanding how our planet works gives us the tools to mitigate earthquake and tsunami risk that will make us a safer and more sustainable society.