Debris flows are water-saturated masses of soil and fragmented rock that can rush down mountainsides, funnel into stream channels and inundate valley floors downstream. These flows can be devastating to people and property. In a recent documentary, NOVA explores events before, during and after the March 22, 2014, landslide near Oso, Washington as well as other landslides from around the world, to find out why these events occur and what can be done to mitigate the hazards. View the program, Killer Landslides, online. Watch what happens when scientists conduct their own debris flow experiments at the USGS debris-flow flume.
During the May 18, 1980, eruption of Mount St. Helens, approximately 2.5 billion cubic meters (3.3 billion cubic yards) of material was deposited in the upper North Fork Toutle River valley. Thirty-four years later, excess sediment continues to wash down the river at a rate of 3 million tons per year, increasing flood risk for local communities and impacting river navigation and migrating fish. Researchers have been looking into ways in which innovation and technology can be used to improve methods of tracking sediment movement in real-time. Results of a new study show that turbidity, or a measure of how cloudy the water is, can be used as a surrogate to quickly estimate suspended-sediment concentration in a highly disturbed river system. The method is promising, providing insight into how the Mount St. Helens sediment-source terrain and depositional areas evolve over time, and in managing excess sedimentation in the lower Toutle River basin. Read Correlations of Turbidity to Suspended-Sediment Concentration in the Toutle River Basin, near Mount St. Helens, Washington, 2010–11.
In the past, drum recorders were used to display seismograms on pieces of paper. These mechanical records have largely been replaced by computers, which digitize the data and store it in digital form. The digital data can be displayed in a variety of ways by a computer, such as a webicorder plot. This webicorder video provides a tutorial for anyone interested in interpreting the seismic records on public webicorder displays.
In the early morning hours of September 23, 2004, a swarm of small-magnitude earthquakes about half a mile below Earth's surface marked the reawakening of Mount St. Helens. On October 1, 2004, the first of several small explosions shot a plume of volcanic ash and gases skyward. A growing welt beneath Crater Glacier heralded the rise of semi-solid magma that erupted onto the surface, forming rocky spines, smooth-sided ridges, and jumbled piles of lava over the next 34 months. During the eruption, scientists made important strides in volcano monitoring, developing new tools for investigation and insight into eruptive behavior. View the 2004-2008 Mount St. Helens Eruption video and read about the eruption in the 2004-2008 event timeline and statistics.