Are we ready for the next tsunami?

"We cannot foresee how well we will be doing in the next tsunami," says Emile Okal. A new "wisdom index" shows mixed results as to how much wiser people have become about tsunamis during the past decade. (Credit: James Guppy/Flickr)

The world may not be well enough prepared for the next significant tsunami, according to a new study that includes a “wisdom index” for 17 tsunamis since 2004.

The 2004 Sumatra-Andaman tsunami was the most devastating in recorded history, killing more than 225,000 people, including thousands of tourists. In a new review of that event and 16 other significant tsunamis since then, researchers used the concept of a “wisdom index” to grade the performance of scientists, decision-makers, and populations at risk.

The index, based on the warning issued (or not) during the event and on the response of the population, shows mixed results as to how much wiser people have become about these natural events and how to reduce their impact.

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“We cannot foresee how well we will be doing in the next tsunami,” says Emile Okal, a seismologist and professor of Earth and planetary sciences at Northwestern University. “I found that mitigation of these 17 tsunamis was rather erratic—there is not sustained improvement with time, nor a clear correlation of the wisdom index with the geographic location of the tsunami source.”

The paper, published in Philosophical Transactions of the Royal Society A, reflects on the progress made since the catastrophic event of 2004 in various aspects of tsunami science, warning, and mitigation and more generally in tsunami resilience, for example, the preventive adaptation of communities to this form of natural hazard.

In addition to the mixed “wisdom indices,” the key results of the study are:

  • Education is important. “One thing is clear, saving human lives is easier when individuals are educated to the risks in question,” Okal says. “Education, in all its forms—formal, classroom, drills, ancestral—works.”
  • Substantial progress has been made in terms of controlling tsunami hazard in the “far field” (a tsunami that originates from a source greater than 1,000 kilometers, or 620 miles, away). Only a handful of deaths have occurred in far field tsunamis since the 2004 Sumatra tsunami.
  • The major challenge remains the so-called “tsunami earthquakes,” events which are not strong enough to alarm the population at risk, yet have considerable tsunami potential.
  • Some paradigms that led scientists to think that mega-earthquakes occur only in certain geological environments—featuring young and fast tectonic plates—had to be revised or abandoned. “For lack of a better understanding, scientists must now assume that mega-earthquakes may occur at any subduction zone,” Okal says. (A subduction zone is where one tectonic plate sinks below another.)
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The study stresses the importance of incorporating new knowledge into tsunami warning procedures and public awareness.

“In this day and age of professional and leisure travel, the general public worldwide should be aware of tsunami risk,” Okal says. “The 2004 Sumatra event was the most lethal disaster in the history of Sweden. The country lost about 500 tourists on the beaches of Thailand.”

Source: Northwestern University