Mount Spurr
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Mount Spurr is a volcano in the Aleutian Volcanic Arc of Alaska, named after United States Geological Survey geologist and explorer Josiah Edward Spurr, who led an expedition to the area in 1898.
The current volcano sits on top of the remains of an old volcano that was destroyed in a giant debris avalanche about 10,000 years ago. Spurr has erupted twice in historic times: in 1953 and again in 1992. Both eruptions led to falls of volcanic ash in the city of Anchorage, Alaska 130 km (81 miles) to the east. As with other Alaskan volcanoes, the proximity of Spurr to major trans-Pacific aviation routes means that an eruption of this volcano can significantly disrupt air travel. Volcanic ash can melt inside jet engines, causing them to fail.
Recent activity
On July 26, 2004, the Alaska Volcano Observatory (AVO) raised the "Color Concern Code" at Spurr from green to yellow due to an increasing number of earthquakes. Earthquakes beneath a volcano may indicate the movement of magma preceding a volcanic eruption, but the earthquakes might also die out without an eruption. In the first week of August 2004, the AVO reported the presence of a collapse pit, filled with water forming a new lake, in the ice and snow cover on the summit. This pit may have been caused by an increase in heat flow through the summit lava dome.
On May 3rd, 2005, a debris flow was observed in webcam images, as well as by a nearby pilot. A subsequent overflight revealed that much of the sitting pond within the melt hole had drained away, a notable depth loss from that observed in an overflight on April 25th.
On September 16th, 2005, AVO included in a weekly update that the current activity at Mount Spurr is declining. A number of factors, including a change of the greenish color in the "melt hole" to one more natural, as well as a down turn in local seismic activity, has led to this conclusion.
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