Tsunami and Risk: How Much We Know Now

Our global wisdom regarding tsunamis is still being built.

That is, a study led by Northwestern University tsunami researcher Emile A. Okal, was recently published in the journal Philosophical Transactions of the Royal Society A. It includes a "wisdom index" and grades our response to 17 tsunamis that have occurred since 2004.

The one that took place in 2004, the Sumatra-Andaman tsunami, was recorded history's most devastating, and it killed more than 225,000 people. The study looked at the performance of decision-makers, scientists and at-risk populations for that set of powerful waves and the 16 noteworthy tsunamis that have followed. The wisdom index itself noted the warning given (or not) for the event and the population's response, according to a release.

"We cannot foresee how well we will be doing in the next tsunami," said Okal, a seismologist and professor of Earth and planetary sciences at Northwestern, in the release. "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 study also concluded, as the release noted:
• Education (formal, drills, classroom, ancestral, any) makes a difference in saving lives

• Scientific progress has occurred in controlling the danger from tsunamis that originate from greater than 620 miles away, known as "far field" tsunamis. Since 2004, only a few deaths have happened in these cases.

• "Tsunami earthquakes" remain the major challenge. Some of these might not be powerful enough to alarm the people who would be affected by them, but they can still cause tsunamis. 

• Scientists have learned that mega-earthquakes can occur at any subduction zone, where one tectonic plate goes below another. This conflicts with the earlier assumption that such large earthquakes took place only with the assistance of young, fast tectonic plates.

"In this day and age of professional and leisure travel, the general public worldwide should be aware of tsunami risk," Okal said in the release. "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."

Also in the release, Okal noted that his tsunami research is influenced by his 20-year collaboration with the director of the Tsunami Research Center at the University of Southern California, Costas Synolakis.

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