Images

Scientists conduct a stream channel cross-section survey of the Toutle River on the north side of Mount St. Helens (view to the southwest).

Map showing one-year probability of accumulation of 1 centimeter (0.4 inch) or more of tephra from eruptions of volcanoes in the Cascade Range.

Map of Mount St. Helens Crater Glacier created from LiDAR data acquired September 2009.

This shaded relief image was produced from LIDAR data. LIDAR is an acronym for Light Detection and Ranging, a modern remote sensing technique used to map topography very accurately—more so than is possible with older techniques. The crater is 1.2 miles (1.9 km) wide east-west. Elsewhere the scale varies owing to the oblique viewing angle.

Mount St. Helens and North Fork Toutle River Channel.

Crews test two methods of measuring discharge of the Muddy River near Mount St. Helens, Washington. The computer and tethered orange float create a vertical discharge profile; the hand-held flow tracker confirms the data. Data collection is becoming more electronic-oriented with periodic confirmation of results by physical observations.

Repairs are made to an Acoustic Flow Monitor (AFM) located at the confluence of the North Fork Toutle River, Maratta, Castle and Coldwater Creeks, where the most recent lahar occurred in November, 2006. AFMs are installed to "hear" when lahars [muddy debris flows] move down channel so affected communities can be warned of the hazard.

This summer, crews made significant modifications to a monitoring station on the southwest flank of Mount St. Helens, greatly improving its operability in winter.

Crews survey Loowit Creek channel and other points inside the crater. Elevation information is used to make a longitudinal profile of the channel, characterizing areas where sediment is either deposited or transported and how the channel is changing with time. View to the north, with Spirit Lake and Mount Rainier in the background.

A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View is to the south of Mount St.

Fieldwork includes direct observations of changes to streams and stream beds to determine how changes will affect the downstream transportation of sediments. Here, the braided North Fork Toutle (left) joins Carbonate Springs Creek (right). View to the east.

Monitoring and upgrading ground-based sensor networks at the most active volcano in the Cascades is an on-going process. Crews made significant modifications to a seismic monitoring station on the southwest flank of Mount St. Helens, greatly improving its operability in winter.

Monitoring stations need to be portable. Weighing about 500 pounds, this "swing set" structure can be airlifted into place or moved, as volcano monitoring needs change. An additional 1,000 pounds of equipment will need to be added to make the station fully functional.

Crews access remote monitoring sites by helicopter. Pictured out the window of the helicopter is a GPS and camera station, dedicated to remotely monitoring changes inside the crater and under the crater floor.

A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View to the south, toward Crater Glacier and the lava domes.

Crater Glacier, located inside the crater of Mount St. Helens, continues to move at an average rate of about 11 cm per day (4.3 inches). During warm weather months, meltwater creates erosional channels on the crater floor.

In summer, the crater of Mount St. Helens is filled with a near constant sound of rockfall from the steep 600 m high (about 2000 feet) crater walls. The falling rock kicks up ash and dust (pulverized rock) as it tumbles onto the crater floor. View of east crater wall.

Steaming continues on the 1980-1986 dome. View to the south and the east arm of Crater Glacier.

A fumerole near the 1980-86 dome keeps an open hole in the east arm of Crater Glacier. The hole is approximately 12 m (40 ft) in diameter, easily wide enough to hold a school bus and deep enough so you could not see the bus' top. View to the south.

Center for the Study of Active Volcanoes (CSAV) students Javier Pacheco (Costa Rica) and Syegi Kunrat (Indonesia) participate in field studies at Mount St. Helens.

Teachers take a guided walk on the Hummocks Trail, learning about the depositional features of the May 18, 1980 eruption.