A new scientific study shows the forces behind glacial earthquakes, and how these important findings can help in measuring massive ice loss that seriously affects the world’s sea level.
Tavi Murray of Swansea University and L. M. Cathles of the Univesity of Michigan along with other US and UK experts decided to install on Helheim Glacier a wireless network of Global Positioning System(GPS) devices. The GPS was intended to determine displacement of surface and velocity on Helheim, which is one of Greenland’s biggest glaciers in the southeast region.
The Greenland ice sheet contributes very significantly to worldwide sea level, with glacial calving causing the loss of almost 50% of its yearly ice mass. In the last two decades, frequency of glacial earthquakes originating in the area has increased seven-fold and direction is moving northward. This development hints that rate of mass loss in Greenland must also be increasing.
A discussion between Murray and Cathles at the meeting of the International Glaciological Society in France inspired the collaboration.
“We both presented in the same session and realized that I was measuring in the lab a very similar signal to what Professor Murray was observing in the field,” related Cathles. “That started a year-long collaboration in which the paper’s co-authors talked regularly and collectively developed a model to explain the GPS observations and a deeper understanding of how glacial earthquakes are generated during an iceberg calving event.”
“We were really surprised to see the glacier flowing backward in our GPS data,” remarked lead author Murray. “The motion happens every time a large iceberg is calved and a glacial earthquake is produced. A theoretical model for the earthquake and the laboratory experiments has allowed us to explain the backward and downward movement. The findings reveal a bit more about glacial behavior. This is a crucial step toward measuring calving events and their contribution to sea-level change, which may give researchers better estimates in the future.”
Cathles lent significant help in the design and laboratory experiments of calving that were later presented in the group’s scientific paper.