Videos

Permanent Site: J1 West Transect; Depth: 9.2 Meters (30.2 Feet); Distance from river mouth: 6.6 Kilometers (4.1 Miles) east; Pre/Post Dam Removal: 1 year pre-dam removal; Lat/Long: 48.13607725,-123.48002186; Site Description: This site is medium depth. Substrates is a gravel/cobble/sand mixture with an occasional boulder.

Permanent Site: J1 East Transect; Depth: 9.5 Meters (31.2 Feet); Distance from river mouth: 6.7 Kilometers (4.1 Miles) east; Pre/Post Dam Removal: 1 year pre-dam removal; Lat/Long: ; Site Description: This site is medium depth. Substrates is a gravel/cobble/sand mixture with an occasional boulder.

Random Site: 5SM18 East Transect; Depth: 6.7 Meters (22.0 Feet); Distance from river mouth: 4.5 Kilometers (2.8 Miles) east; Pre/Post Dam Removal: 3 years pre-dam removal; Lat/Long: 48.1357869,-123.5095144; Site Description: This is a shallow site. Sediment is a gravel/sand mixture. Red, green and brown seaweed is abundant.

Random Site: 5SM18 West Transect; Depth: 6.1 Meters (20 Feet); Distance from river mouth: 4.5 Kilometers (2.8 Miles) east; Pre/Post Dam Removal: 3 years pre-dam removal; Lat/Long: 48.13592923,-123.51082988; Site Description: This is a shallow site. Sediment is a gravel/sand mixture. Red, green and brown seaweed is abundant.

The rapid onset of unrest at Mount St. Helens on September 23, 2004 initiated an uninterrupted lava-dome-building eruption that continued until 2008. The initial phase produced rapid growth of a lava dome as magma pushed upward.

Mount St. Helens reawakened in late September 2004. Small magnitude earthquakes beneath the 1980-1986 lava dome increased in frequency and size, and a growing welt formed on the southeast margin of the previous lava dome and nearby portions of Crater Glacier.

Throughout the eruption, scientists installed monitoring stations to track volcanic activity, deployed temporary monitoring ""spiders"", monitored the temperature of lava spines and created time-lapse of dome growth. During the 3+ years of the eruption, lava piled up to form a new dome 460 m (1,500 ft) high.

The first priority of any eruption is to assess current status and what might happen next. To accomplish this, Mount St. Helens became one of most heavily monitored volcanoes. At the start of the 2004–08 eruption, 13 permanent seismic stations operated within about 12 miles of Mount St. Helens.

From 2005 to 2010, the U.S. Geological Survey-Cascades Volcano Observatory operated a remote camera on the northwest flank of Mount St. Helens. Looking into the crater, the camera captured hourly photographs of volcanic dome growth during the 2004-2008 eruption.

Events that occurred in the crater during the 2004–2008 eruption were recorded by a network of seven remote, telemetered digital single-lens reflex (DSLR) cameras installed on the crater floor and rim. The resulting time lapse images constitute a valuable and visually compelling record of dome growth and the resulting response of Crater Glacier.

Lava spines continue to emerge onto the crater floor of Mount St. Helens in 2005. By April 2005, spine 4 is broken and pushed away by spine 5.  The nearly vertical spine 5 has a smooth, gouge-covered surface, growing at an average rate of 4.3 meters per day.

Growth and disintegration of lava spines continued at Mount St. Helens through the first 8 months of 2005. Rather than building a single dome-shaped structure, the new dome grew initially as a series of recumbent, smoothly surfaced spines that extruded to lengths of almost 500 m.

Within the crater of Mount St. Helens, the 2004–2008 lava dome grew by continuous extrusion of degassed lava spines. To track growth and anticipate what the volcano might do next, scientists installed monitoring equipment, including a camera and gas sensing instruments, and made helicopter overflights to collect the temperature (FLIR) of the growing dome.

Compilation video of significant events from the dome-building eruption at Mount St. Helens, from October 1, 2004 to March 15, 2005, including steam and ash eruptions, growth of lava spines, helicopter deployment of monitoring equipment, collection of lava samples, and FLIR thermal imaging of rock collapse on lava dome.

By late October 2004, a whaleback-shaped extrusion of solid lava (called a spine) emerged from Mount St. Helens' crater floor. The 2004–2008 lava dome grew by continuous extrusion of degassed lava spines that had mostly solidified at less than 1 km (0.62 mi) beneath the surface.

Following unrest that began on September 23, 2004 and the steam and ash eruptions in early October, extrusion of solid magma typified the 2004-2008 eruption at Mount St. Helens. The magma is unusually gas poor and crystal rich.  Several meters of pulverized, variably sintered rock commonly coat the emergent lava spines, lending them a smooth appearance.

On October 11, 2004, spines of solid, but still hot, lava punctured the surface of the deformed glacier, initiating a new dome-building phase of activity in the crater of Mount St. Helens. By late October, a larger whaleback-shaped extrusion of solid lava (called a spine) emerged from the crater floor.

After two weeks of increasing seismicity, Mount St. Helens began erupting on October 1, 2004. The first of several explosions shot a plume of volcanic ash and gases into the atmosphere. Four additional steam and ash explosions occurred through October 5, and three produced noticeable fallout of fine ash downwind.

On October 1, 2004, an explosion in the crater of Mount St. Helens sent ash and water vapor several thousand feet into the air. It was the dramatic beginning of an eruption that continued for the next 3+ years. The explosion fractured Crater Glacier and hurled rocks for at least one-half mile across the western half of the glacier and the 1980-1986 lava dome.

New Mapping Techniques Reveal Potential Seismic Sources Beneath Seattle

By Richard J. Blakely, Geophysicist and Ralph A. Haugerud, Geologist

USGS scientists C. Dan Miller, Don Mullineaux, Mike Doukas, Norm Banks, Don Swanson, and Richard Waitt talk about their experiences at Mount St.