A weather eye on fire and ice –
Iceland is an active geological hotspot. Just how active becomes evident when one considers that, since the end of the last Ice Age, around 200 volcanoes have erupted, adding about 500 cubic kilometers of molten rock (magma) to the island’s surface. Humans began to settle on Iceland just over 1100 years ago and, in that brief period alone, about 30 volcanic systems have been active. Of course, fire is not the only element that defines the island’s unique character. About 10% of Iceland’s surface is covered by ice. “And many powerful eruptions take place under glaciers, as a result of seismic activity“, says Dr. Ulrich Münzer of the Geology Section of the Department of Geological and Environmental Sciences at LMU Munich. “These eruptions cause large volumes of ice to melt, resulting in catastrophic glacial floods.”
So far, it has not been possible to produce early and reliable forecasts of either subglacial or surface eruptions but, thanks to remote sensing, this may change in the near future. The radar satellite TerraSAR-X was launched in 2008 and is run by the German Aerospace Center (DLR). Its orbit follows the day-night boundary, and it can provide imaging data with a resolution equivalent to 1 meter from more than 500 km above the Earth.“The satellite’s orbit brings it over the same point on the globe once every 11 days“, says Münzer, “but because Iceland lies so far North, the areas of interest to us can be imaged twice almost every day, and the images are available for analysis within a few hours.“
Changes in topography, such as those that result from rising pressure in the magma chamber for instance, can be detected in near real time. Because the volcano’s behavior can be followed more or less continuously, it becomes possible, for the first time, to give early warning of impending eruptions. The international monitoring team, which includes Icelandic scientists as well as glaciologists affiliated with the Bavarian Academy of Sciences and the DLR, has even observed a glacial flood in detail. Glacial floods occur when gigantic volumes of ice are rapidly melted as the result of an eruption. They can have catastrophic consequences because they have the potential to devastate huge areas in a very short time. This underlines the significance of an early-warning system.
Like some other volcanoes in Central Iceland the volcano Eyjafjalla lies buried under ice that is up to 200 meters thick and the glacier Eyjafjallajökull has an area of 80 square kilometers. At 600 square kilometers, its neighbor glacier Myrdalsjökull is even larger, and incorporates the Katla volcano. Katla has been under continuous observation by TerraSAR-X because an eruption is overdue. TerraSAR-X will be joined by a sister satellite, TanDEM-X, which becomes operational in 2011. “In the course of just under 3 years, the two satellites together will map the whole land surface of the Earth“, says Münzer. ”This will provide us with an up-to-date digital model of the continents at unprecedented resolution." (suwe)
"NRT-Monitoring am Vulkanausbruch Eyjafjallakökull (Island) mit TerraSAR-X"
Ulrich Münzer et al.
Schriftenreihe der Deutschen Gesellschaft für Photogrammetrie, Fernerkundung und Geoinformation, PFG 2010, Issue 5, pp 337-352, October 2010
Dr. Ulrich Münzer
Department of Earth and Environmental Sciences
Division of Geology
Phone: +49 (0) 89 / 2180 – 6589