Power of a 8.9 Earthquake

[Rolo]

Dec. 27 - As at least nine nations searched for the missing following the world’s biggest earthquake in 40 years, geologist Gianluca Valensise of the Italian Institute of Geophysics and Vulcanology spoke with NEWSWEEK’s Eric Pape Monday about the shifts in the earth’s tectonic plates that sparked a 9.0 quake and a 33- to 40-foot-high wave that blanketed thousands of miles of Asian, Indian and African coastlines with death and destruction.

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What about other events, like say the detonation of a nuclear bomb?
This quake was more powerful. It has been calculated that the energy released on Sunday was 23,000 times that of the explosion of the nuclear bomb at Hiroshima (Japan). A large portion of the earth’s crust—1,000 km (620 miles) in length by 100 km (62 miles) in width running from Western Sumatra to Myanmar—moved. And that is where they are feeling the aftershocks now.

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How would you compare this quake to others of the last decade?
It’s just so much bigger. The Bam earthquake in Iran a year ago that destroyed a very vulnerable city (and killed more than 26,000) was much smaller. But this earthquake will not be famous for the shaking, it will be known for the tsunami, which is pretty unusual.

The risks of tsunamis have been greatly underestimated. A tsunami can travel 3,000 or 5,000 km (1,900-3,000 miles), in this case to regions like Somalia where people died on the beach because they had no idea that there had even been an earthquake. This is something that people will have to face in the next few years.

How fast can such a wave go?
In the open ocean, it can travel as fast as 800 kilometers (500 miles) per hour—like a commercial airplane—so it took two or three hours. This leaves time for a system to warn people, but there wasn’t one in place.

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If a quake this magnitude hit on land, how would it have been different?
First of all, on land, you wouldn’t have the tsunami. Then, depending on whether it was close to a large city, it would have destroyed it—or done nothing. In the high mountains of Tibet, there are 8.5s that change the landscape, but they don’t kill anyone. Earthquakes like the one yesterday, in a subduction zone, have a repeat time of 200 or 300 years. A subduction zone is where one plate flows under another—in this case the Indian plate flows under the Burma plate. Subduction zones have the fastest repeat times in the world.

Could we see another huge earthquake in the near future?
This was so large that it consumed all of the stored energy in the area. We are recording aftershocks, but no one is expecting another humongous one.

The chance of a massive aftershock?
Very low. We are recording magnitude 6s and a few larger than that, but an 8 on the Richter scale seems unlikely in the same region—unless this quake triggers one in a different area. Some people are saying that another one is more likely to the southeast of Sumatra, in the coming days or weeks—but it probably wouldn’t be as big. This was the fifth largest of the last century.

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What are the most likely spots for another monster quake or a tsunami?
The ring around Sumatra toward the east and Japan. It is where the largest tsunamis in the world strike. The region where 95 percent of the earth’s seismic activity is released and where there are the most active volcanoes is part of a band spanning from Myanmar, around Sumatra to the southeast toward the Sea of Japan, Alaska and the Western U.S., and then south toward New Zealand.

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