Japan Tsunami Broke Off Antarctica Icebergs Twice the Size of Manhattan

Japan Tsunami Broke Off Antarctica Icebergs Twice the Size of Manhattan

Laura Matthews
International Business Times

© NASA/handout
Thick
cloud cover briefly fell away to reveal this first image of icebergs
breaking away from the Sulzberger Ice Shelf due to sea swell from the
Tohoku Tsunami, which had originated 8,000 miles away about 18 hours
earlier. The icebergs can be seen behind a thin layer of clouds just off
the ice shelf near the center of the image

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.


© NASA/handout
After
picture of the Sulzberger Ice Shelf illustrate the calving event
associated with the Japan earthquake and resulting tsunami that occurred
on March 11, 2011

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.