The large landslide that occurred on March 22, 2014 near Oso, Washington, was unusually mobile and destructive. Eighteen million tons of sediment slid downslope and crossed the half-mile wide river floodplain in about 1 minute with devastating consequences to the local community. A major focus of USGS researchers has been to understand the landslide's behavior. This published study reveals that the collapsing material compressed already-unstable wet sediment to produce liquefaction and decreased friction, leading to the landslide's high mobility. Numerical simulations indicate that the landslide process at Oso could have unfolded very differently (with much less destruction) if initial conditions had been only subtly different. Understanding of the Oso event adds to the knowledge base that can be used to improve future landslide hazard evaluations. Read Landslide mobility and hazards: implications of the 2014 Oso disaster and watch the computer simulations online.
Falling ash, even in low concentrations, can disrupt human activities hundreds of miles downwind of a volcano, and drifting clouds of fine ash can endanger jet aircraft thousands of miles away. The economic effects of airborne volcanic ash were demonstrated during the 2010 eruption of Eyjafjallajökull volcano in Iceland, when flight cancellations and delays throughout Europe caused billions of dollars in economic loss to airlines and travelers. The most effective way to reduce risk from dispersed volcanic ash is to forecast where it will go and what areas it will affect. A computer model called Ash3d uses current wind speed and directional data along with eruption characteristics to plot the potential path of an ash cloud. See today's computer simulations for hypothetical eruptions at Mount St. Helens and read more about Ash3d.
Scientists from CVO and the Istituto Nazionale di Geofisica e Vulcanologia (Italy) are taking advantage of advances in technology to design and construct lightweight, portable, power-conserving volcanic gas monitoring equipment. The instrument (active long-path differential optical absorption spectroscopy or LP-DOAS) uses novel fiber-coupling and ultraviolet LED technology to send a beam of ultraviolet or visible light to a reflector located tens to hundreds of meters away. Characteristic absorption lines of trace gases present in the light path are measured in the spectrum of returning light. The robust design and versatility of the instrument make it a promising tool for monitoring of volcanic degassing and understanding processes in a range of volcanic systems. Read the abstract Development of a portable active long-path differential optical absorption spectroscopy system for volcanic gas measurements.
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.