Is Japan's tsunami linked to climate change?

mongabay.com
March 11, 2011



Could the earthquake that triggered Japan's devastating tsunami be linked to climate change?

The short answer is probably not, but recent research suggests that changing climate has the potential to influence earthquakes in some parts of the world

Scientists have shown that weight shifts caused by melting glaciers can trigger tectonic activity. As ice melts and waters runs off, tremendous amounts of weight are lifted off Earth's crust. As the newly freed crust settles back to its original, pre-glacier shape, it can cause seismic plates to slip and stimulate volcanic activity, according to research into prehistoric earthquakes and volcanic activity.


Approaching tsunami in Japan. Photo courtesy of Reuters.

Map of the Senadai Earthquake
Map of the Senadai Earthquake 2011
Analyzing an 800,000-year record of volcanic activity in eastern California, Allen Glazner, a University of North Carolina-Chapel Hill geoscientist, found evidence that "peaks of volcanic activity occurred when ice was retreating globally," as told to the Wall Street Jorunal's Sharon Begley in 2006. "At first I thought it was crazy, but other scientists also found evidence that climate affects volcanism."

With Earth's glaciers and ice gaps melting at increasing rates due to climate change, it is conceivable that we could see further impact from "isostatic rebound" in the Earth's crust. Work by Patrick Wu, a professor of geophysics of the University of Calgary, suggests that past disappearance of ice "may still be contributing to quakes in eastern Canada."

"The pressure of the ice sheet suppresses earthquakes, so removing that load triggers them," Wu told Begley. "Present-day earthquakes may have their origin in postglacial rebound."

Bill McGuire, professor of Geophysical Hazards at University College, spelled out the scenario further in a 2006 article in New Scientist, titled "Climate change: Tearing the Earth apart?"

"It shouldn't come as a surprise that the loading and unloading of the Earth's crust by ice or water can trigger seismic and volcanic activity and even landslides. Dumping the weight of a kilometer-thick ice sheet onto a continent or removing a deep column of water from the ocean floor will inevitably affect the stresses and strains on the underlying rock," he wrote. "[While] not every volcanic eruption and earthquake in the years to come will have a climate-change link... [As] the century progresses we should not be surprised by more geological disasters as a direct and indirect result of dramatic changes to our environment."

Japan's quake

Japan lies in one of the world's most seismically active areas between four major continental and oceanic plates: the Pacific Plate, Philippine Plate, Eurasian Plate and North American Plate. The country accounts for roughly 20 percent of the world's earthquakes of magnitude 6 or bigger. It has also suffered from more than 200 tsunamis (tsunami is a Japanese word).

Nevertheless the March 11, 2011 quake had a devastating impact. The 8.9-magnitude earthquake was centered 130 kilometers (81 mi) east of Sendai, Honshu, Japan, or 373 kilometers (232 mi) from Tokyo, according to the United States Geological Survey. It generated a tsunami that caused waves of up to 10 meters to swamp coastal areas of eastern Japan. Thousands were feared dead in the immediate aftermath of the quake and tsunami.

The earthquake was the strongest on record for Japan and one of the world's five most powerful earthquakes since modern seismological record-keeping began.















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mongabay.com (March 11, 2011).

Is Japan's tsunami linked to climate change?.

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