Nearly three decades after the catastrophic eruption of Mount St. Helens, the impact on the forest in the blast zone is still obvious in this astronaut photograph. South of the mountain, lush green forests cover the landscape, while north of the mountain, vegetation remains sparse.
On May 18, 1980, Mount Saint Helens volcano erupted. Because the eruption occurred in an easily accessible region of the U.S., Mount St. Helens has provided unprecedented opportunities for U.S. researchers to collect scientific observations of the geology of an active volcano and document the regional ecological impact and recovery from an eruption.
After more than a decade of inactivity, Mount St. Helens rumbled back to life in September 2004. An ongoing series of tremors within the volcano coupled with upward movement of magma toward its caldera prompted geologists to issue a Level 3 alert on October 2, stating that Mount St. Helens could experience a moderately severe eruption at any time. In order to help geologists and volcanologists assess the nature and magnitude of the risk, on September 24, 2004, NASA flew a low-altitude aircraft carrying the MODIS/ASTER Airborne Simulator (MASTER) directly over the volcano to obtain high-resolution images of its caldera.