Scientists have found the exact mechanisms behind glacial earthquakes, which are seismic rumblings that occur as a result of glaciers breaking apart and falling off in chunks into the ocean.
This type of earthquake was only recently discovered. In Greenland, the occurrence has increased by up to seven times over the past 20 years.
The earthquake continues to move upward, signifying that ice loss is becoming frequent due to high environmental temperatures.
In a new study, a team of researchers found the exact geophysical effects that happen during glacial earthquakes, as well as measures on how to possibly evaluate ice loss anywhere in the world.
Researchers from the Swansea University in the UK, the Lamont-Doherty Earth Observatory at Columbia University, the University of Michigan and the Emory University studied one of the largest glaciers in the southeast part of Greenland, namely the Helheim Glacier.
This large glacier is said to cast off icebergs comparable to the size of small cities, as it measures approximately 4 miles in width and 100 miles in length. The team of researchers went to the Helheim for one month in the summer of 2013 and attached networks of Global Positioning System (GPS) apparatuses to the edged surfaces to evaluate the degree and speed under which any movement on the glacier occurs.
The findings, published in the journal Science, show that a kickback occurs every time a part of the glacier drops into the water. The other parts of the glacier simultaneously exhibit swift downward and backward movements.
The researchers compared the activity to a skateboard that escapes a rider's foot and swivels backwards as the rider leans forward. The researchers then compared the collated seismic information to the kickbacks that occurred. They created models of the glaciers and conducted water tank simulations to come up with more concrete evidences.
According to the team, the impact of the kickbacks can be so high that it can actually revert the flow of the glacier in a matter of minutes. After the experiment, the scientists came up with an estimate reversal of about 130 feet per day backward and 95 feet per day forward.
"This gives us a far better explanation for the source of the earthquakes than we had before," said Meredith Nettles, study co-author and a seismologist at Columbia University's Lamont-Doherty Earth Observatory. "It will move us a long way towards being able to use remotely detectable seismic signals to estimate mass loss from a major class of events in both Greenland and Antarctica."
For the past years, the ice sheet of Greenland has been undergoing significant ice loss. In fact, 50 percent of annual losses are caused by calving. Based on statistical data, glacial earthquakes have notably increased from six in 1993 to 42 in 2013.
Having adequate and correct knowledge about the mechanisms of glacial earthquakes is crucial to the maintenance of sea levels. This knowledge can give valuable insights about the extent of ice loss in the world's ice sheets.
Photo: NASA ICE | Flickr
