Douglas Wiens, of the Washington University in St. Louis, in Antarctica.
Click on image for full size
Image Courtesy of Douglas Wiens, Washington University in St. Louis
Study of Glacial Earthquakes Shakes Up Idea of How Ice Streams Move
News story originally written on June 5, 2008
New research shows that part of the Whillians Ice Stream in West Antarctica moves more than two feet twice every day in an earthquake-like pattern equal to a Magnitude 7 earthquake. In an earthquake, stress builds between two plates on the Earth's crust. Finally, one plate or the other moves, causing shudders and jolts at the Earth's surface.
A similar movement was observed in the Whillians Ice Stream by the research team. The researchers have measured what they are calling a "stick-slip" interaction on the huge ice stream.
The "stick-slip" pattern in the ice sheet is very different that the way scientists usually think of ice streams as flowing at a constant speed.
"Glaciologists model the flow of glaciers using the assumption that it's basically a kind of creeping kind of motion. But recently we've been seeing seismic signals coming from a number of ice streams and glaciers, and no one's been able to interpret them," said Douglas Wiens, a professor of Earth and planetary sciences at Washington University in St. Louis, who led the research team.
The movement happens twice a day and seems to be related to the daily tides of the Ross Sea. The slip takes place over about 25 minutes, so scientists standing right on the slipping ice stream don't feel anything. Most rock earthquakes, which can take place in a few seconds, are felt strongly by people in the area.
The new findings don't say if these ice movements have anything to do with global warming. But they are significant because they add another piece to the puzzle of ice dynamics.
Shop Windows to the Universe Science Store!
Our online store
on science education, classroom activities in The Earth Scientist
specimens, and educational games
You might also be interested in:
What Will You Find There? If you travel to the South Pole, you will find the continent of Antarctica surrounded by the Southern Ocean. The geographic South Pole is marked by a large sign that scientists...more
The ground underfoot might seem like itís not going anywhere but it is. It moves. If it moves all of a sudden the ground shakes. Thatís an earthquake! Earthquakes happen as pieces of the Earthís crust...more
Many forces change the surface of the Earth over time. The largest force that changes our planetís surface is movement of Earth's outer layer in a process called plate tectonics. As shown in this picture,...more
This page is not yet developed at the elementary level. Please check back for updates or click on the "Intermediate" button above for information....more
Frozen water is found in many different places on Earth. Snow blankets the ground at mid and high latitudes during winter. Sea ice and icebergs float in the chilly waters of polar oceans. Ice shelves are...more
Earthís climate is getting warmer. During the past 100 years Earthís average temperature rose about 0.6į Celsius (1.0į F). Things that people are doing like burning fossil fuels, changing the way land...more
Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. Adam Kent, a geologist at Oregon State University, says this...more