The tsunami generated by the powerful earthquake that shook Japan on March 11 sent waves an entire hemisphere away that sliced off about 50 square miles of icebergs in Antarctica that were twice the surface area of Manhattan, NASA scientists say.
Kelly Brunt, a cryosphere specialist at Goddard Space Flight Center, and her colleagues were able to link the calving of icebergs from the Sulzberger Ice Shelf in Antarctica following tsunami that sent waves 8,100 miles away.
The finding is presented in details in a paper published in the Journal of Glaciology. It is the first direct observation of its kind, said NASA.
Japan's powerful magnitude-9.0 earthquake killed more than 20,000 people and caused more than $230 billion in damages, according to the World Bank. The tsunami also damaged the Fukushima Daiichi nuclear power plant in Fukushima prefecture, making it the worst nuclear disaster since Chernobyl in 1986 in Ukraine.
When the Tohoku Tsunami was triggered in the Pacific Ocean this spring, the team immediately looked south using multiple satellite images and was able to spot new icebergs floating off to sea shortly after the sea swell of the tsunami reached Antarctica.
The icebergs, which were twice the surface area of Manhattan, were able to break away because there were massive waves exploding from the epicenter of the earthquake. About 18 hours after the earthquake trembled, several chunks of ice were seen breaking away.
Historical data showed that this particular piece of ice hadn't moved in at least 46 years prior to the tsunami. Scientists were able to watch the Antarctic ice shelves in as close to real time as satellite imagery allows, and catch a glimpse of a new iceberg floating off into the Ross Sea.
"In the past we've had calving events where we've looked for the source. It's a reverse scenario - we see a calving and we go looking for a source," Brunt said in a statement. "We knew right away this was one of the biggest events in recent history - we knew there would be enough swell. And this time we had a source."
Though the swell was likely only about a foot high when it reached the Sulzberger shelf, the consistency of the waves produced enough stress to slice the glacier. The Sulzberger shelf faces Sulzberger Bay and New Zealand.
Radar data from the European Space Agency satellite, Envisat, which can penetrate clouds, found images of two moderate-sized icebergs - with more, smaller bergs in their wake, NASA said. The largest iceberg was about four by six miles in surface area, which is about equal to the surface area of one Manhattan.
The breakaway of the iceberg ended scientists speculations that such an event could happen and at the same time provided some light on knowledge of past events.
"In September 1868, Chilean naval officers reported an unseasonal presence of large icebergs in the southernmost Pacific Ocean, and it was later speculated that they may have calved during the great Arica earthquake and tsunami a month earlier," Emile Okal at Northwestern University said. "We know now that this is a most probable scenario."
Douglas MacAyeal, an observer from the University of Chicago, has said the recent event is more proof of the interconnectedness of Earth systems.
"This is an example not only of the way in which events are connected across great ranges of oceanic distance, but also how events in one kind of Earth system, i.e., the plate tectonic system, can connect with another kind of seemingly unrelated event: the calving of icebergs from Antarctica's ice sheet," MacAyeal said.
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