EXPLORE: What Happens at Plate Boundaries?

Volcanoes are most often found along the boundaries where tectonic plates meet. Volcanoes are especially prevalent at convergent plate boundaries. One such zone, which encircles the Pacific Basin, is known as the Pacific Ring of Fire. Alaska, which is located at the boundary of the Pacific and North American plates, is home to more than 50 active volcanoes. Scientists study and vigilantly monitor Alaska's volcanoes because there are serious volcanic hazards that place both people and property at risk.

Alaska Volcano Observatory (AVO), uses a variety of tools—including seismometers (instruments that measure motions of the ground) and satellite images—to gather data about volcanoes. Months or weeks before an eruption, a volcano can show signs of unrest. For example, the movement of magma within a volcano can generate earthquakes and cause the surface to swell. Data gathered by satellites provides further information. For example, synthetic aperture radar (SAR) satellites can show changes in the shape of a volcano, thermal infrared (TIR) images display temperature differences, and color composite images provide information about surface materials. AVO analyzes satellite data twice daily for thermal anomalies (areas of higher temperature than normal) and ash plumes. Other instruments and techniques, such as global positioning systems, are also used to monitor changes in the surfaces of volcanoes (such as swelling and deformation). Volcanoes outside the seismic network are monitored by satellite imagery; observations of airplane pilots may prompt investigations as well.


Source: "Explore Alaska's Volcanoes." Teachers' Domain. 29 Jun. 2009. Web. 25 Jun. 2011.<http://www.teachersdomain.org/resource/ean08.sci.ess.earthsys.akvolcano/>.