Kristin M. Schild is a recently minted Dartmouth PhD, whose primary area of focus has been in understanding the ice dynamics of outlet glaciers in Greenland, Alaska and Antarctica through on site measurements and satellite remote sensing. She gave a fascinating talk on her work in remote parts of the world and the life of being a working scientist.
She began by talking about a recent paper that led to cross-over discoveries in her area of study. A group of seismologists were studying earthquakes looking for patterns that would allow them to predict earthquake activity. They found that a number of long wave earthquakes were happening in Greenland. Greenland does not sit on any existing faults however. Equally puzzling was the fact that earthquake activity was highly concentrated in the summer months which would not occur due to normal plate activity. A collaboration between glaciologist and seismologists led to a theory that the earthquakes were caused by glacial motion.
Ms. Schild was part of the team that went to research whether this hypothesis was in fact true. Because the Greenland Ice Sheets hold a tremendous amount of fresh water (she said that if the sheets were to melt, that the water released would raise global sea levels by 7 meters), there is high priority for scientists in understanding the Greenland glaciers and their dynamics. In describing an operation reminiscent of an adventure movie, Ms. Schild talked about the challenges of glacier saftey training, C130 Hercules transport, arctic camping, helicopter landings on glaciers and icebergs and the Arctic Wolves' propensity for chewing through battery cables. Using a combination of GPS sensors, weather stations, time lapse photography and tide gauges, her team was able to prove that the original hypothesis was in error.
Her team developed a new theory that the earthquakes were caused by the pressure released during iceberg calving events — the process where glacial ice “calves” off from the main sheet to form icebergs. She described and showed pictures of the scale of these events - she said that within 45 minutes a 3KM section of ice would separate. To put this in perspective, she said that each of these ice sections would supply enough water for the City of Los Angeles for two years. The energy release is what creates a long-wave earthquake of 4.6-5.1 Richter scale that could be measured in NY. Surprisingly though, these events cannot be felt at the location.
There was still a problem with their theory however. Not every sizable calving resulted in an earthquake. The team determined that a series of conditions needed to be present for this phenomenon to occur: (1) the iceberg needed to rotate as it calved; (2) the event needed to occur in a location where the ice could come in contact with the fiord bed; (3) icebergs needed to have sufficient mass and dimension; and, (4) the iceberg needed to rotate with sufficient velocity. While this phenomenon only occurs with a portion of the glacial calving events that occur each year, she said that it offered her and other scientist a valuable new tool. For the first time scientist have a way of measuring calving events during the long winter polar darkness. Prior methods relied on satellite photography which is impossible during the winter months.
Ms. Schild finished by talking about the joys of her career and why everyone should be a scientist. In particular she pointed to a couple of key ideas:
- You get to ask hard questions (and you don’t have to be right with your answers!)
- You get to create your own methods to answer questions and, as a result, you often get to work with experts from unrelated fields.
- You get to figure out how the world works (she added that the Earth is amazing).
- You get to travel to amazing places (and get paid to do it).