<P> Mount St. Helens showed significant activity on March 8, 2005, when a 36,000 - foot (11,000 m) plume of steam and ash emerged--visible from Seattle . This relatively minor eruption was a release of pressure consistent with ongoing dome building . The release was accompanied by a magnitude 2.5 earthquake . </P> <P> Another feature to emerge from the dome was called the "fin" or "slab ." Approximately half the size of a football field, the large, cooled volcanic rock was being forced upward as quickly as 6 ft (2 m) per day . In mid-June 2006, the slab was crumbling in frequent rockfalls, although it was still being extruded . The height of the dome was 7,550 feet (2,300 m), still below the height reached in July 2005 when the whaleback collapsed . </P> <P> On October 22, 2006, at 3: 13 p.m. PST, a magnitude 3.5 earthquake broke loose Spine 7 . The collapse and avalanche of the lava dome sent an ash plume 2,000 feet (600 m) over the western rim of the crater; the ash plume then rapidly dissipated . </P> <P> On December 19, 2006, a large white plume of condensing steam was observed, leading some media people to assume there had been a small eruption . However, the Cascades Volcano Observatory of the USGS did not mention any significant ash plume . The volcano was in continuous eruption from October 2004, but this eruption consisted in large part of a gradual extrusion of lava forming a dome in the crater . </P>

What type of magma feeds into mount st. helens