A recent investigation by NASA scientists revealed a connection between the March 2011 earthquake and tsunami that crippled Japan’s Fukushima nuclear plant, and the calving of icebergs from the Sulzberger Ice Shelf in Antarctica.
The finding, published online Monday in the Journal of Glaciology, marks the first direct observation of such a connection between tsunamis and icebergs.
Typically, scientists notice massive walls of ice breaking loose from the Arctic shelf, and must work backwards through time to ascertain the source. This time, say researchers, they knew the source ahead of time, and only had to wait to confirm the results.
“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,” said Kelly Brunt, a cryosphere specialist at Goddard Space Flight Center. “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.”
When the Tohoku Tsunami was triggered in the Pacific Ocean on March 11 this spring, Brunt and colleagues watched as massive waves exploded out from its epicenter. Then, they looked south, watching swells of water swarming toward an ice shelf in Antarctica, 8,000 miles (13,600 km) away. About 18 hours after the earthquake occurred, those waves broke off several chunks of ice that together equaled about two times the surface area of Manhattan. According to historical records, this particular piece of ice hadn’t budged in at least 46 years before the tsunami came along.
Previous studies have theorized that the presence of sea ice, greatly diminished thanks to the effects of global climate change, is instrumental in preventing massive ice calving by buffering ocean swells that can cause icebergs to break loose. According to Douglas MacAyeal at University of Chicago who assisted Brunt with the research, the bay in front of the Sulzberger shelf was largely lacking sea ice at the time of the tsunami.
Image Credit: Flickr - kaet44