What Type of Lava Was Produced in the Most Recent Mount St. Helens Eruption?

The most recent volcanic eruption of Mount St. Helens in Washington State, which began in October, 2004, produced hot, but solid, extrusions of smooth-sided lava called "spines." The extrusion of the solid lava spines continued until January 2008, producing more than 120 million cubic yards of solidified lava. Unlike the previous and catastrophic eruption, which occurred in 1980 and produced thick lava flows, the eruptions occurring between 2004 and 2008 produced only solid lava extrusions and resulted in no loss of life or property.

During the more than 3 years of volcanic activity spanning 2004 through early 2008, the rising solid-lava spines extruded through the crater floor and created a new 1,500-foot-high lava dome. The extrusions grew, at times, as quickly as 6 feet per day. Dense clouds of ash, dust and vapor were emitted, but the volcanic activity that began in 2004 produced no notable explosive events.