Geology And Geophysics

Scientists uncover new data about Japanese tsunami of 2011

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"Scientists uncover new data about Japanese tsunami of 2011"
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A team of 27 scientists from 10 countries worked on the Japan Trench Fast Drilling Project (JFAST) to discover the nature of the geological phenomenon that led to the March 2011 tsunami in Japan that had devastating consequences for Japan and the world (particularly when one considers the long-lasting effects from the pollution resulting from the nuclear power plant destruction).

According to the International Business Times, the scientific results of this study (published in the journal Science) have determined that the massive earthquake and resulting tsunami were the result of an “unusually thin and slippery geological fault within the Japan Trench.”

Studying the Japan Trench and resulting findings

According to a geophysicist from the University of California, Santa Cruz, who worked on the project, the “Tohoku fault is far more slippery than anyone expected.” For the project, scientists bored three holes into the Japan Trench, part of the Pacific Ring of Fire.

The Japan Trench is where two of the world’s major tectonic plates (the Pacific Plate and the North American Plate) meet. The joint of the meeting point is known as the subduction zone, and at this location, the North American Plate rises over the edge of the Pacific Plate, bending it and forming the trench.

Deep beneath the sea floor, the rocks are strong and less malleable. Closer to the surface, the rocks are softer and less compressed. By drilling in the Japan Trench, scientists were able to learn the following: “What the core samples show, for the first time, is that the fault, particularly near the sea floor is composed of less than five meters of very fine volcanic sediment, highly altered to a special type of clay (smectite), which act as an incredibly slippery lubricant and allowed the huge quake to occur.”

As a result, a displacement of as much as 50 meters (or about 164 feet) caused a magnitude 9 earthquake and the resulting tsunami, which was the product of so much shifting of rock.

Measuring the heat created

Another element of the JFAST Project was the creation of a borehole observatory, which has allowed scientists to “obtain crucial temperature measurements” of the fault that created the devastating chain of events, according to Science News. Located 7 kilometers (or about 22,900 feet) below the ocean’s surface, the team of scientists was able to collect information from a string of temperature and pressure sensors that were installed deep within the Japan Trench.

While data from the water pressure and temperature measurements is still being analyzed, the mere collection of such critical data was unprecedented. Notes one scientist, “Nobody had done rapid response drilling in the ocean, nobody had drilled anything substantial under 7 kilometers of water, nobody had placed an observatory in a fault that deep and nobody had retrieved a string of instruments from that deep.” In short, the work done here is ground-breaking.

This new research, it is hoped, will better prepare scientists to anticipate the actions of other Ring of Fire faults (for example, beneath the eastern coast of New Zealand) to better prepare citizens if possible. The initial results of the data now being harnessed will be presented this coming May 2014 at a meeting of the Japan Geoscience Union.

More about this author: Christine Zibas

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