# Volcano Watch — The three U.S. Volcano Observatories

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The U.S. Geological Survey's Volcano Hazards Program funds the operations of three volcano observatories in the United States. They are the Hawaiian, Cascades, and Alaska Volcano Observatories, and, as their names imply, each is responsible for monitoring volcanoes in a specific geographic area.

The U.S. Geological Survey's Volcano Hazards Program funds the operations of three volcano observatories in the United States. They are the Hawaiian, Cascades, and Alaska Volcano Observatories, and, as their names imply, each is responsible for monitoring volcanoes in a specific geographic area.

The Alaska Volcano Observatory (AVO) was recently in the news when Pavlof Volcano, located near the tip of the Alaska Peninsula, began to erupt on Monday, September 16. Although the continuing eruption poses no immediate threat to people living in the area, AVO personnel in Anchorage were manning the Observatory around the clock to monitor the activity.

This constant surveillance is required because volcanoes of the Pacific "Ring of Fire" are capable of ejecting ash to great heights. Many airline routes are over the Alaskan/Aleutian volcanoes, and the ash plumes can reach altitudes at which the planes fly and can damage or disable the jet engines.

When a large explosive event is detected by AVO, the Federal Aviation Administration (F‘A‘ā) is immediately notified, and planes are diverted around the volcano. The drifting ash cloud is tracked with radar by both ground and satellite platforms, and the F‘A‘ā is kept informed.

The eruption from flank vents on the western side of Puu Oo continues unabated, with lava flowing through the six-mile long tube system and entering the ocean at Laeapuki. During the early morning hours of Thursday, September 19, a large block of the Lae`apuki bench slid into the ocean. No one witnessed the collapse, but sufficient energy was transferred to the ground for the HVO seismic network to detect the event, which lasted for eight minutes.