“Being able to go out into the field and place instruments on the glacier to study it while it’s surging is a rare opportunity,” said Jukes Liu, one of two Boise State geophysics graduate students who conducted field work on an Alaska glacier this fall.
It seems almost impossible that glaciers the size of a city can move, but they do. However, there are certain kinds of glaciers, called surging glaciers, that experience periods of motion in which the glacier is suddenly in high gear, moving more than 10 times their normal rate.
There is much mystery around what specifically causes glacial surging, and why it only impacts certain glaciers. Geophysics faculty Ellyn Enderlin and Dylan Mikesell were awarded a National Science Foundation Arctic Natural Sciences award to study the surges of Turner Glacier, in Yakutat, Alaska. The project is in collaboration with assistant professor Tim Bartholomaus at the University of Idaho with the full project totaling $1.2 million.
Turner Glacier is special in that while many surging glaciers surge at intervals of 15-20 years (sometimes even a century), Turner moves at an interval of every 5-8 years. During a surge, Turner goes from moving a meter per day to about 20 meters per day.
“If you stood there long enough or if you took photos, you could piece enough together that you could actually see that it was moving,” said Enderlin. “That’s pretty unusual for glaciers outside Greenland and Antarctica.”
This short interval of surging makes it optimal to study for trends over a long period of time. Bartholomaus and University of Idaho student Chris Miele, as well as Boise State geophysics students Liu, Kate Bollen, and research assistant Thomas Otheim began their field work on the 40-kilometer-long glacier in late August. The team relied on helicopter transportation to and from the glacier, and despite unpredictable weather were able to accomplish their goals.
“In the two weeks out in Yakutat, Alaska, our field team of five accomplished all of our research goals. We battled the weather in a race against time to install 26 geophysical instruments on Turner Glacier (original Tlingit name is Sít’ Kusá),” said Liu.
“There are five different types of sensors,” explained Mikesell. “Seismic sensors are located on and around the glacier to measure vibrations caused by the glacier movement and water flow in and beneath the glacier, GPS sensors are located on the ice to measure how the surface of the glacier is actually moving, weather stations are there to log temperature and precipitation, a time-lapse camera is there to take photos of the terminus of the glacier and help us monitor the location and shape of the terminus through time, and an ice-penetrating radar that shoots radio waves into the ice is placed at the top of the glacier.”
From this wide array of sensors, the team will be gathering data over the next few years to get the bigger picture of why some glaciers surge in an effort to predict future surges for this glacier and others.
“The end goal is to understand the physical drivers of surge and figure out why some glaciers surge and others do not. This will then help us predict and model things like sea-level rise more accurately. It will also help us determine if currently non-surging glaciers might start surging in the future if the environmental conditions change,” said Mikesell.
“The glacier itself was absolutely stunning and humbling to work on. I learned a lot of new field skills throughout my time there and came away with new knowledge about Turner Glacier’s behavior,” said Liu.