If you didn’t already know, there are volcanoes under the Antarctic surface. When I say under – I mean underneath massive ice sheets. Up until now, however, there was a lot of debate about what was causing the unusual amount of volcanic activity. Especially because the Antarctic is covered in ice. Recent research has found a source of magma that is fueling the volcanoes underneath Antarctica. The source is known as a “hotspot”. Which is a similar mechanism to what we find in the Hawaiian Islands and the geothermal activity in Yellowstone. According to Forbes, there are two reasons that this was difficult information to unearth:
- The first is the difficulty of measuring anything underneath kilometers of ice. Typically geoscientists gain a better understanding of the Earth’s inner workings by sending sound waves into the ground and measuring the time and angle at which they return to the surface. Using complex mathematical algorithms, geophysicists are able to reconstruct a three-dimensional picture of the subsurface. However, this was difficult to do when any acoustic signal has to travel through kilometers of chaotic ice, causing significant noise in the subsurface “picture” beneath Antarctica.
- The second is the counterintuitive nature of having a massive heat source underneath an area that is covered with kilometers of ice. With an average ice sheet thickness of 2.16 km and a maximum thickness of around 4.7 km, it’s hard to believe there is a massive heat source similar to the one in Yellowstone sitting beneath the ice. How has the heat source not prevented ice build up?
In order for researchers to work through these questions, they used a numerical model to help constrain the heat required to produce the melting they measure in Antarctica. While direct measurements underneath Antarctica are difficult and few, there are a number of meltwater outflow. This allowed the research team to constrain their model.
It’s known that there are rivers and lakes beneath Antartica which drain meltwater into the ocean. Some are even as large as Lake Erie. The researchers were able to predict heat sources underneath the ice using constrained melt rates. They found that the heat coming from beneath the surface is constrained to 150 milliwatts per square meter. In comparison, the average heat flux from the Earth is 40-60 milliwatts per square meter. The hot spot beneath Yellowstone National Park reaches 200 milliwatts per square meter. Which makes this not overly hot, but certainly hotter than the average on Earth.
The area where there is a lot of heat, known as Marie Byrd Land mantle plume would have formed between 50 and 110 million years ago – long before this particular land was hidden by ice. The fact that it hasn’t melted more ice is interesting to me. I am not a scientist, but prolonged exposure to heat seems like it would make ice melt. Yes, its kilometers thick, but this hot spot has been there for millions of years. Maybe even 100 million. I look forward to hearing what researchers can tell us about what might happen with this in the years to come. What kinds of impacts might it have on our oceans? The climate change deniers will be happy about this discovery.