The Condit Dam was a hydroelectric facility constructed in 1912–1913 on the White Salmon River, Washington. Over its nearly 100-year existence, the dam trapped sand, silt, and clay that washed down from the southern Washington Cascade Range, including Mount Adams. The dam was breached in late 2011 and removed to restore fish passage to upstream spawning grounds.
Cameras were set-up to capture erosion of reservoir sediment following breaching and measurements of suspended sediments were made at stations downstream for a 15-week period. Upon opening the outlet tunnel at the base of the dam, the impounded Northwestern Lake drained within 90 minutes. As reservoir erosion proceeded, sediment concentration increased and flow became hyperconcentrated, at first noisy and turbulent but then quiet and viscous. Within 24 hours, 20% of the sediment stored behind the dam washed downstream. In the days and weeks after the breach, erosion and transport of sediments slowed. The channel evolved, lowering to near its original elevation at a gauge site within 15 days of breaching.
The study of the geomorphic response to dam removal was an opportunity to observe erosion processes and the downstream behavior of released sediment. New insights may be applied to the understanding of other disturbances that inject substantial sediment volumes into rivers such as volcanic eruptions, landslides, or when floods entrain great volumes of channel sediment. Read Rapid reservoir erosion, hyperconcentrated flow, and downstream deposition triggered by breaching of 38-m-tall Condit Dam, White Salmon River, Washington.
USGS and its partners invite educators to join us for a fun and informative teacher workshop at Mount Rainier National Park. This five-day classroom and field-based workshop offers science information, hands-on classroom activities, and resources that will enrich your understanding of Cascade volcanoes and aid in your ability to teach about volcanoes in your classroom and on class field trips. Credits and clock hours are available.
Visit the Mount Rainier Teacher Professional Development webpage to register; download the Mount Rainier Teacher Training flyer to share with colleagues.
Explosive eruptions are awesome displays of nature's power that dramatically alter landscapes downwind or downstream of a volcano. Vegetation is damaged, topography may be changed, and large volumes of fragmental material are deposited on hillsides, valley floors and into streams.
While explosive eruptions are hazardous in their own right, the stream drainages responding and adjusting to such volcanic disturbances can pose additional hazards on downstream communities up to 60 miles (100 km) or more from a volcano. Affected drainage basins typically exhibit higher rates and volumes of precipitation runoff, and sediment erosion and transport, than in similar unaffected basins. Recovery of disturbed fluvial systems takes decades to centuries to reach a stable geomorphic state. Read more in Hydrogeomorphic effects of explosive volcanic eruptions on drainage basins.
A monitoring spider is now on display at the Coldwater Science and Learning Center at Mount St. Helens. Visitors have an opportunity to see the instrument up-close and learn more about how it is used to monitor eruptive activity inside the crater.
The spider was engineered and deployed during the 2004-2008 eruption of Mount St. Helens to detect and triangulate shallow earthquakes, monitor local ground deformation and uplift, detect lightning that might indicate an ash eruption and low frequency sound from explosions. The spider embodies the ability of people to find new ways to solve problems and design instrumentation that increases our understanding of volcanic eruptions.
The Coldwater Science and Learning Center is open Saturday and Sunday from 10 am to 6 pm. The Center can also be reserved for schools, education and science groups interested in taking field trips and doing research at Mount St. Helens. Contact Grace Schmidt at the Mount St. Helens Institute for reservations. View information about the Center at Mount St. Helens National Volcanic Monument.
InSAR (Interferometric Synthetic Aperture Radar) is a technique for mapping subtle ground deformation using radar images from Earth-orbiting satellites. With its global coverage and all-weather imaging capability, InSAR has become an increasingly important technique for studying volcanoes in remote regions such as the Aleutian Islands.
For a new book, InSAR Imaging of Aleutian Volcanoes - Monitoring a Volcanic Arc from Space, USGS scientists processed nearly 12,000 SAR images to produce about 25,000 interferograms for 52 Aleutian volcanoes that have been active during historical time. During the 20-year study period, InSAR detected some form of deformation at more than 80% of the 44 volcanoes with adequate InSAR coverage.
The spatial distribution of deformation data from InSAR, combined with other monitoring data and eruption information, helps scientists to link changes on the surface to processes occurring beneath the volcano. View details at InSAR Imaging of Aleutian Volcanoes: Monitoring a Volcanic Arc from Space, read more at Monitoring Ground Deformation from Space.
May 18 marks the 34th anniversary of the catastrophic eruption of Mount St. Helens. The eruption remains a seminal historical event; studying it and its aftermath revolutionized the way scientists approach the field of volcanology. Not only was the eruption spectacular, it occurred in daytime, at an accessible volcano, in a country with the resources to transform disaster into scientific opportunity, amid a transformation in digital technology. Lives lost and the impact of the eruption on people and infrastructure downstream and downwind made it imperative for scientists to investigate events and work with communities to lessen losses from future eruptions. Follow the signs and symptoms of volcanic unrest that led to the May 18, 1980 eruption in the volcano activity update archives. Sign up with the Volcano Notification Service to receive news of current activity.
Lahars (volcanic debris flows) are a hazard at many of the world's volcanoes. Consisting primarily of water, mud and rock debris with a consistency often compared to wet concrete, lahars surge down steep volcano flanks into and along river channels tens, to a hundred or more miles (kilometers) downstream, destroying property and claiming lives. The Laharz desktop software helps users plot areas of potential inundation by lahars, debris flows and rock avalanches, using a digital elevation model for a base, and user-set parameters for the lahar initiation location(s) and volume(s). The result shows the extent of inundation in connected stream drainages and areas downstream. The impacted areas can be combined using a geographic information system (GIS) with other types of volcano hazard information, local infrastructure, hydrology, population, and contours or shaded relief to produce volcano hazard-zonation maps, expanding the ability of communities to understand hazards and mitigate the effects of future volcanic eruptions. Open-File Report 2014-1073 contains an explanation of how to install and use the software (Laharz_py) and a sample data set for Mount Rainier, Washington.
During the month of May, residents are encouraged to take the necessary steps to find out about volcanic hazards where they live, work and play, and how to survive and recover from the next eruption.
Slowly emerging patterns of behavior at Mount St. Helens are giving scientists at the USGS-Cascades Volcano Observatory and the Pacific Northwest Seismic Network new insights into activity beneath the volcano. Since the end of the 2004-2008 dome-building eruption, scientists have been monitoring subtle inflation of the ground surface and minor earthquake activity that is reminiscent of that seen in the years prior to the 2004-2008 eruption.
Careful analysis of these two lines of evidence now gives us confidence to say that the magma reservoir beneath Mount St. Helens has been slowly re-pressurizing since 2008. It is likely that re-pressurization is caused by arrival of a small amount of additional magma 4-8 km (2.5-5 miles) beneath the surface. This is to be expected while Mount St. Helens is in an active period, as it has been since 1980, and it does not indicate that the volcano is likely to erupt anytime soon. Re-pressurization of a volcano's magma reservoir is commonly observed at other volcanoes that have erupted recently, and it can continue for many years without an eruption.
To learn more, field work this summer will include measuring the types and amounts of gases being released, and the strength of the gravity field at the volcano. The information collected at Mount St. Helens continues to help scientists analyze behaviors here and at other volcanoes and to improve eruption forecasting capabilities. View the full and read the . Sign up for the Volcano Notification Service to receive your own updates about volcanic activity at Mount St. Helens or other volcanoes. Read more about Monitoring Mount St. Helens online.
CVO staff and sediment specialists from USGS offices around the country led the Sediment Data Collection Techniques training course in Castle Rock, Washington. The week-long course was attended by 30 students representing the USGS, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, and the Nooksack and Klamath Tribes. The course provided participants with an understanding of basic fluvial-sediment concepts, sediment sampler characteristics, sampling protocol and techniques, laboratory analysis, surrogate technologies, and quality-assurance procedures. Field training exercises on the Cowlitz and North Fork Toutle Rivers gave students valuable hands-on experiences. Erosion of 1980 deposits at Mount St. Helens resulted in higher sediment loads in the Toutle and lower Cowlitz Rivers, decreasing the carrying capacity of channels, increasing flood risk, and affecting aquatic habitats. Sampling is a method of tracking the movement and volume of material moving downstream. For more information, see USGS Surface Water Information -- Fluvial Sediment, and Hazards from Post-Eruption Excess Sediment at Mount St. Helens.
Over the past half-century, great advances have been made in understanding debris flow behavior. Studies find that most debris flows originate on slopes that are steeper than 25 to 30 degrees and are mantled with low-cohesion soils and/or fragmented rocks that have become at least partially saturated by water. The resulting downslope flow can scour and erode a channel with devastating consequences for communities in its path. This new article describes the debris flow process from initiation to end, and provides guidance for assessing debris flow hazards. Read more at Debris flows: behaviour and hazard assessment.
An episode of strong seismic tremor (a continuous release of seismic energy) occurred during the build-up to the 2004-2008 eruption of Mount St. Helens. This episode was remarkable because no explosion or eruption immediately followed. Research found that in this case, the tremor occurred as gas-poor magma under Mount St. Helens was slowly forced upward for about 49 minutes, breaking and tearing the fabric of the rough conduit walls. The seismic waves produced by this movement resonated within the conduit to form hybrid waves that were recorded in far-field seismic stations as tremor. The conduit resonance masked the source of the tremor, making it difficult to determine if the tremor was leading to an explosion. An understanding of the different ways tremor can be generated requires that information from other sources, such as visual observations, deformation, geology and gas geochemistry, be used in order to interpret events that could lead to an eruption. Read more at Volcanic tremor masks its seismogenic source: Results from a study of non-eruptive tremor recorded at Mount St. Helens, Washington.
Around 170,000 years ago, explosive volcanic eruptions near Bend, Oregon, produced gravity-driven currents of hot volcanic gas and pyroclastic rocks. When the flows stopped moving, they were hot enough to weld together. This new study examines changes in permeability and porosity during welding, helping to understand how the deposits initially formed and how fluids, such as groundwater, flow through volcanic tuffs. Read Compaction and gas loss in welded pyroclastic deposits as revealed by porosity, permeability, and electrical conductivity measurements of the Shevlin Park Tuff.
The Community Foundation for Southwest Washington, in cooperation with the U.S. Geological Survey's Volcano Science Center, invites applications for the 2014 Jack Kleinman Volcano Research Grants Program. Stipends of $500 to $2,000 are available to senior undergraduates and graduate students who are conducting research in volcanology, preferably in the Cascade Range, Aleutian volcanic arc, Hawaii, Yellowstone, or Long Valley caldera. Read the detailed grant application instructions to find out more.
It has been a busy year for the USGS Volcano Science Center, as shown in this sample of our favorite 2013 images: three volcanoes in Alaska erupted for several weeks each, Kīlauea Volcano in Hawaii continued its 31-year long eruption, Pagan Volcano in the Commonwealth of the Northern Mariana Islands showed persistent low-level activity, and several Cascades volcanoes, as well as the Yellowstone and Long Valley calderas, demonstrated their active status with small swarms of earthquakes. Detailed data analyses over this past year continue to increase our understanding of volcanoes and collaboration among geoscientists and hazard planners, both nationally and internationally, drew attention to volcanic hazards and the need for continued monitoring and community preparation for future eruptions. View the USGS Volcano Science Center Images and Events from 2013 online.
The southernmost Lake Natron basin is located along the East African rift zone in northern Tanzania. It is here where Oldonyo Lengai, Tanzania's most active volcano of the past several thousand years, built its edifice. Oldonyo Lengai's eruptions are chiefly explosive, producing tephra fall, pyroclastic flows, and lahars; its history includes periodic collapse of the volcano's flanks and deposition of volcanic debris-avalanche deposits across the southern basin floor. A cooperative venture among USGS and coauthors from the Geological Survey of Tanzania and the University of Dar es Salaam, produced this geologic map of the area including new radiometric ages and geochemical analyses. View the Geologic map of Oldonyo Lengai (Oldoinyo Lengai) volcano and surroundings, Arusha Region, United Republic of Tanzania: U.S. Geological Survey Open-File Report 2013-1306 and read the accompanying pamphlet.
A photo assistant with The Columbian (Vancouver, WA) recently discovered unprocessed black-and-white film taken by staff photographer Reid Blackburn in April, 1980. The images show a restless Mount St. Helens five weeks before the catastrophic May 18 eruption that took Mr. Blackburn's life and the lives of 56 others. Read about the discovery in Photographer's parting shots of Mount St. Helens and view footage of the eruption on the Mount St. Helens Multimedia page.
This season's first lake-ice quakes are occurring at Newberry Volcano. Aided by record-setting subfreezing temperatures, the popping and cracking of ice in the caldera's lakes is picked up by local seismic stations. The lake-ice quakes do not resemble standard volcanic low-frequency or high-frequency events and are sporadically observed in the winter at ice-covered lakes in Yellowstone, Long Valley, and elsewhere. Ice quakes were first noticed at Newberry in December 2011, after the new seismic network was installed. The sensitive network was designed to detect earthquakes and other seismicity that occur beneath the Newberry Volcano and has also provided insight into the way sound travels through the upper crust in the area. Visit the Newberry webpage to learn more about this volcano.
On September 28, after about 10 hours of steady rain, an acoustic flow monitor (AFM) on the South Fork Toutle River recorded the passage of small debris flows. The AFM showed significantly elevated signals for about three hours as water, mud and rock rolled downstream in small surges. During recent field work, crews visited the area to see the evidence -- remnant debris flow surfaces on channel margins, new deposits, mud lines and bent, scoured alders. The flow likely traveled for over a mile downstream of the AFM location. No damage to infrastructure was reported. Read more about sediment erosion, transportation and deposition at Hydrologic Monitoring at Mount St.Helens.
This newly published Scientific Investigation Map (SIM) highlights the geologic history and structural features of the westernmost portion of the Columbia River Gorge, and areas in Clark and Multnomah Counties. The SIM shows 27 million year-old Elkhorn Mountain lava flows, Columbia River basalts, and vents of the Boring Volcanic Field. SIM 3257 describes how the area was profoundly affected by glacier-outbursts from Glacial Lake Missoula and the ancestral Columbia and Sandy Rivers, furthering our understanding of the history and hazards of the environment in which we live. View the Geologic Map of the Washougal Quadrangle, Clark County, Washington, and Multnomah County, Oregon and explore other Scientific Investigation Maps for nearby Clark and Cowlitz Counties (Washington), Columbia and Multnomah Counties (Oregon), Mount St. Helens, Three Sisters, Mount Mazama, Lassen and Medicine Lake.
Forty conferees from the 2013 National Science Teachers Association meeting in Portland, Oregon, participated in a field trip to CVO to learn about Cascade hazards and volcano monitoring. Teaching about Cascade volcanoes has many benefits--sparking enthusiasm for science and math, helping students to understand the connection between volcanoes and people, students and teachers can help to develop preparedness strategies for their schools and communities, and volcano studies bring opportunities to explore current events in the Pacific Northwest and around the globe. Online resources are available for teaching and learning about local volcanoes in accordance with state standards. See more at Teaching Resources and Website Use in the Classroom.
Question: If you change a single variable in a debris flow, what difference does it make? Answer: Do experiments and find out! New side-by-side videos show what happens when you change the volume or type of material in a debris flow, the characteristics of the bed, and what happens when the flow encounters a corner or wall. The experiments confirm two decades of scientific results and help scientists understand how small changes can affect the behavior of destructive flows. This publication is available only on the web, Video Documentation of Experiments at the USGS Debris-Flow Flume 1992-2006 (amended to include 2007-2013). A description of the area where the experiments were conducted is at Debris-flow flume at H. J. Andrews Experimental Forest, Oregon. Additional interpretations and data from other experiments at the USGS debris-flow flume can be found in other online reports.
Over 200,000 children from over 70 countries will explore natural disasters and what can be done to keep people safe, in the 2013 "Nature's Fury" FIRST LEGO challenge. Researchers interested in focusing on the Cascade volcanoes for this year's challenge have many resources available to them:
This summer, USGS-CVO monitoring stations at Crater Lake, Oregon, were upgraded to send digital signals. The digital stations provide higher quality data and therefore more accurate recordings of seismicity within the caldera. Once installed, the stations are simpler to maintain than analog stations. The monitoring network currently monitors both seismicity and ground deformation in the caldera, created when the 12,000 ft (3,660 m) high Mount Mazama collapsed 7,700 years ago following a large eruption. For more information on volcano monitoring, view Monitoring Cascade Volcanoes.
Last month, CVO scientists participated in a community-wide science, technology, engineering, and math (STEM) festival. The event, held at Clark College, encouraged adults and youth of all ages to participate in hands-on activities, experiments and talks given by experts. STEM-Fest participants had the opportunity to closely examine ash from the 1980 eruption of Mount St. Helens, look at rock samples, see minerals in thin section, conduct an experiment demonstrating ash transport, and talk about the volcanic hazards in their communities. For more information about volcano hazards and simplified maps showing hazard areas, view Volcano Hazards in the Cascade Range.
Colombia suffered one of the worst volcanic disasters of the 20th century in November, 1985, when ice-clad Nevado del Ruiz volcano erupted and communities at its base were destroyed by large lahars (volcanic debris flows). More than 23,000 fatalities occurred in the city of Armero and surrounding communities. The disaster had a profound and constructive effect on scientific and disaster management in Colombia and around the world.
Organized by the USGS-CVO and the Washington Emergency Management Division with support from the USAID's Office of U.S. Foreign Disaster Assistance, scientists, first-responders and emergency/hazard planning officials met in Colombia and again in the Puget Sound area to observe, learn and absorb best practices for preparing for and responding to volcanic crises. Read more at Colombian and US Officials Meet to Save Lives through Exchange, and Colombians Urge Pacific Northwesterners To Appreciate Lahar Danger.
Summer is a busy season for USGS-CVO field crews. When weather permits, monitoring stations are repaired, replaced or fitted with new technologies to improve volcano monitoring. Crews also survey and make direct observations of landforms, such as channels and streams. The information is used to improve our understanding of Mount St. Helens (and other volcanoes) during both eruptive and non-eruptive periods. View images of Mount St. Helens 2013 Summer Fieldwork online.
Scientists from CVO and the Alaska and Hawaii Volcano Observatories installed a novel sulfur dioxide (SO2) camera system at Kilauea's summit caldera. The system uses two ultra-violet cameras to continuously measure the emission rate of SO2 released from the active summit eruption site with imagery streaming in near real-time. This is one of the first camera-based SO2 gas monitoring systems to be installed at a volcano. The high spatial and temporal resolution of the instrument is expected to provide unique insights into degassing processes at Kilauea, with application to other active volcanoes worldwide. For more information, read a recent article on improvements to gas monitoring techniques, Applying UV cameras for SO2 detection to distant or optically thick volcanic plumes.
Ten middle school teachers from around the Pacific Northwest took part in a 5-day classroom/field studies training workshop at Mount Rainier National Park. Led by USGS-CVO and National Park Service educators, participants learned about the tectonic setting of Mount Rainier, how volcanoes work, volcanic hazards and processes, reading the geologic record and preparing for the next eruption in the Cascade Range. The information will be used in classrooms to augment science curriculum and to increase community hazard awareness. Hands-on teaching activities and information about Cascade volcanoes and volcanic processes are available in Living with a Volcano in your Backyard -- An Educator's Guide with Emphasis on Mount Rainier.
Each year, gas samples are collected from the fumaroles on the north side of Mount Hood's Crater Rock and the samples are taken back to the laboratory for an analysis of the gases' chemical composition and concentration. Gas compositions are also measured by analyzing the absorption of sunlight that occurs as it falls through the gas cloud, as pictured. By routinely collecting gas samples and comparing their composition to past measurements, scientists can track the geochemical evolution of the volcanic system and become aware of any subtle changes that might indicate a rekindling of eruptive activity. For more information, visit Volcanic Gas Monitoring at Mount Hood, Oregon.
USGS scientists and foreign students with the Center for the Study of Active Volcanoes' (CSAV) International Training Program recently visited Mount St. Helens to observe and learn about the volcanic deposits that record the eruptive history of the volcano. The students are part of a program to share volcano monitoring techniques and experiences, and build working relationships within the international community. Read The Columbian newspaper's story Scientists form volcanic bond at Mount St. Helens, watch a video and view a photo gallery of the field studies, online.
Volcano scientists from Ecuador, Colombia, Peru, Costa Rica, El Salvador, Canada, Indonesia, Italy, and Papua New Guinea, have been at CVO for the past couple weeks as part of a cooperative education program of the USGS and the University of Hawai`i, with support from the joint USGS-USAID Volcano Disaster Assistance Program. Through in-class instruction and field exercises at Mount St. Helens and Mt. Hood, scientists learned about a variety volcano monitoring methods, data analysis and interpretation, volcanic hazard assessment, and rapid response during volcanic crises. The knowledge will be used by the students to help prepare citizens for volcanic eruptions. Learn more at the Center for the Study of Actives Volcanoes.
USGS-CVO Research Geophysicist Jeff Wynn was awarded a 3rd patent for developing a new method of mapping and characterizing hydrocarbon plumes in seawater. As designed, an array of multiple streamer cables with electrical transmitters and receivers are towed in the sea behind a ship. As the streamer passes through a hydrocarbon plume, the receivers detect a capacitive response produced by the hydrocarbons. A data-acquisition system onboard the ship processes the signals to develop detailed maps of plume locations, and can be used to track and characterize how the plume changes over time. In sea-trials, the system also turned out to be well-suited to locating buried metallic infrastructure and old shipwrecks.
The IDES (Increasing Diversity in Earth Sciences) Program seeks to strengthen the understanding of Earth science and its relevance to society among broad and diverse segments of the population. Recently, CVO IDES student intern Joe Bard and geologist Dave Ramsey met with IDES students on a field trip to Newberry Volcano, to talk about the geology of the area, the recently-published geologic map database (USGS Data Series 771), and volcano hazards. Click on the link to find out more about IDES.
Modeling is becoming an increasingly important tool for interpreting observations and understanding the complexity of volcanic systems. A physics-based model, as described in Bayesian inversion of data from effusive volcanic eruptions using physics-based models: Application to Mount St. Helens 2004–2008, links data collected during the recent eruption to show that magma under Mount St. Helens likely resides between 8 and 16 km (5 to 10 miles) below the crater floor in an elongated chamber with a width of roughly 2 km (1.2 miles). Future work will help to create a more sophisticated model to improve on these estimates. To the extent that a model is a reasonable representation of a volcanic system, comparing model predictions with actual data can be used to infer properties of the volcanic system at Mount St. Helens and at other active volcanoes.
Recent field observations of Crater Glacier show the glacier terminus has advanced about 40 meters (about 131 feet) since June 2012. The glacier is moving at an average rate of about 11 cm per day (4.3 inches) -- roughly the distance from your wrist to the tip of your thumb (per day). The glacier continues to calve into the head of Loowit stream. Read more about Glaciation at Mount St. Helens, online.
The shield-shaped Newberry Volcano (central Oregon) is the product of deposits from thousands of eruptions, including at least 25 in the past 12,000 years. This geodatabase, used to produce U.S. Geological Survey Miscellaneous Investigations Series Map I-2455, provides information on Newberry rocks and deposits based on their composition, age, and lithology, along with locations of vents, hydrothermal features and even craters pocking the surface of the Big Obsidian Flow. Also included are links to view or print the map sheets and the accompanying pamphlet. View the Database for the Geologic Map of Newberry Volcano, Deschutes, Klamath, and Lake Counties, Oregon: USGS Data Series 771, online.
The new Mount St. Helens Science and Learning Center webpage features eruption images and videos, time-lapse photos of ecosystem changes, volcano facts, publications, and ways to explore the volcanic landscape this summer. Visit the Mount St. Helens Science and Learning Center to learn more.
At the USGS-CVO, scientists conduct research about volcano hazards so that policymakers and the public can prepare adequately for the next eruption in the Cascades. Here are opportunities to engage USGS scientists and learn more about hazards in your area and how to be prepared.
Two educator training workshops are offered this summer at Mount St. Helens and Mount Rainier. The workshops feature informative talks on Cascade volcanoes and volcanic processes, ideas for classroom activities, hikes into the field, and tips for organizing school field trips to visit the volcanoes.
Other upcoming events for educators include:
Mount St. Helens seized the world's attention in 1980 when the largest historical landslide on Earth and a powerful explosive eruption reshaped the volcano, created its distinctive crater, and dramatically modified the surrounding landscape. Read about what has happened at the volcano since 1980 in a new USGS Fact Sheet, "Mount St. Helens Then and Now--What's Going On?" The digital version contains six embedded videoclips to help learn about the dramatic changes taking place on and beneath this active volcano.
Meet scientists of the USGS Volcano Science Center and learn more about their jobs as they watch over 169 known active volcanoes within the US and its territories. These two-to-four-minute web shorts provide glimpses into some of many professions that contribute to the science of volcanology.
The Three Sisters are a cluster of volcanoes near Bend, Oregon, that bear little family resemblance. North Sister is the elder, now a glacially ravaged stratocone that consists of hundreds of thin rubbly lava flows. Middle Sister is an andesite-basalt-dacite cone, with gentle-sloping west flank and steep east face. Snow and ice fills the youngest cone, South Sister, a bimodal rhyolite-to-intermediate composition edifice that was constructed within the last 50,000 years. The authors of this new geologic map spent about one month each summer from 2000 to 2009 mapping the volcanic field on foot and collecting samples for geochemical analyses. View the product of their efforts, Geologic Map of Three Sisters Volcanic Cluster, Cascade Range, Oregon.
Earlier this month, members of the Volcano Disaster Assistance Program (VDAP) helped lead a workshop with Latin American Volcano seismologists in Manizales, Colombia. The workshop brought together seismologists and volcanologists from 12 nations in Latin American and the Caribbean to share information and improve seismic methods to forecast volcanic eruptions. USGS scientists discussed a global data set of observed patterns of precursory earthquakes, use of seismic data to monitor volcanic debris flows, and participated in discussion groups on infrasound and a variety of other topics related to eruption prediction. For more information on VDAP’s work, visit the Volcano Disaster Assistance Program website.
The Mount St. Helens website has been updated with a new design and the most recent scientific research about its rich volcanic history. The change was made as a part of the ongoing update to all Volcano Hazards Program webpages. We hope you enjoy this new learning experience about the most active volcano in the contiguous U.S. Photo from October 5, 2004.
A new video shows changes inside Mount St. Helen's crater from 2004 to 2012. The images were created from aerial photographs that were processed with photogrammetry software to collect a 3-D point cloud, which was then used to create shaded relief digital elevation models (DEMs). Information regarding volume and rates of growth of the lava dome and Crater Glacier are extracted from DEMs and used to monitor surface changes in the crater. View the time-series online, Time-series of dome and glacier growth at Mount St. Helens, Washington, 2004-2012. You can also view camera-captured time-lapse for this same period but from a different perspective. Images taken by a remote camera on the northwest flank of the volcano show dome growth and the movement of Crater Glacier across the crater floor. Watch Mount St. Helens' Runaway Glacier.
Field work continues at the volcano. The focus of winter work is primarily on maintaining remote monitoring equipment, making direct observations of the impacts of storm events, and measuring the transportation of sediments in swift moving streams. The work is necessary to keep the early warning systems functional, assess hazards, and engage in mitigation measures, if needed. View the Winter 2013 Fieldwork images online.
Crews visited the Spirit Lake gaging station at Mount St. Helens to correlate the water level on a staff outside the station with readings from pressure transducers inside the tunnel. The outlet of Spirit Lake was dammed by a debris avalanche during the May 18, 1980 eruption. In 1985, a tunnel was constructed so that as the level of the lake rises, water flows through the tunnel to South Coldwater Creek. Logs and other debris floating in the lake can become lodged near the tunnel opening. The transducers are used to track water level changes inside the tunnel. By comparing the water level changes in the tunnel with the lake level measured at the gaging station, scientists can determine if the logs are stacking up, and potentially, blocking the tunnel entrance. Read station notes and find data online at the Spirit Lake at Tunnel gaging station.
Over 90,000 maps and reports by more than 600 publishers are available in one location - on the recently redesigned National Geologic Map Database. Users can go online to view geologic, geophysical, natural resource and hazard maps for many locations within the United States. Popular formats make the database easy to use. What is the geology of your backyard? Find out by searching The National Geologic Map Database.
We are currently upgrading our website to provide a new look and improved functionality. When completed, the website will offer streamlined access to information about volcano hazards and preparedness, maps, images, monitoring data, and volcano histories. We apologize for any inconvenience while this process is underway.
CVO scientists John Ewert, Nate Wood, and Willie Scott conducted a FEMA Volcanic Crises Awareness Course at the local emergency management agency (Clark Regional Emergency Services Agency or CRESA). The course, developed by the National Disaster Preparedness Training Center at University of Hawaii with substantial contributions from other USGS scientists, provides an overview of volcanic processes and hazards, current monitoring and hazard assessment tools, volcano warning systems, and community preparedness. The course is designed to assist decision-makers, emergency managers, response personnel, planners, and other professionals from both public and private sectors in understanding and preparing for future volcanic crises. For more information on emergency preparedness and how you can be ready, visit CRESA.
The 1980 eruption of Mount St. Helens, Washington, clogged the upper reaches of the North Fork Toutle River with sediment. In 1989, the U.S. Army Corps of Engineers completed a Sediment Retention Structure (SRS) to minimize the downstream transport of the sand, silt and gravel. Since construction of the SRS the sediment trap has filled to more than 50 percent of capacity, but its efficiency has diminished and sediment is bypassing the structure. CVO Geophysicist Roger Denlinger conducted numerical simulations to assess the ability of the structure to withstand potential large flow events, either from debris flows or from sediment-laden floods. In the model, large debris flows originating from release of lake water or from an eruption of Mount St. Helens never topped SRS, but instead filled the braided channels upstream of the SRS. These types of flows would however, reduce sediment storage capacity in the future. Read Effects of catastrophic floods and debris flows on the sediment retention structure, North Fork Toutle River, Washington, online. You can also check out discharge data from the North Fork Toutle River station located below the SRS. In 2012 the U.S. Army Corps of Engineers raised the level of the spillway to trap additional sediment.
CVO Scientists John Ewert, Andy Lockhart, Peter Kelly, and Chris Lockett were featured in a short program about volcanic hazards and the evolution of the monitoring techniques aimed at understanding volcanic behavior. The catastrophic eruption of Mount St. Helens in 1980 re-emphasized the need to closely study and monitor Cascade volcanoes by analyzing the seismicity associated with magma or other fluids moving under the volcano, the swelling of a volcano’s flanks, and the type and amount of volcanic gases emitted. With so many people and infrastructure located near potentially active Cascade volcanoes, it is important to have integrated, continuous monitoring networks so people can be prepared for the next eruption. Watch the story Deceptive Beauty: Volcanoes Ready to Blow, online.
When magma rises towards the Earth's surface, it produces emissions of sulfur dioxide and other gases. Scientists use miniature spectrometers to measure the absorption of light as it passes through a volcanic plume to determine the concentration and emission rate of gases in the plume. CVO post-doctoral researcher Christoph Kern, with support from colleagues from CVO, the University of Heidelberg and the Hawaiian Volcano Observatory, has developed a new method for evaluating spectroscopic data that takes into account the different paths light can take on its way through the plume. Using the new technique, the researchers are now able to make significantly more accurate assessments of degassing activity at Kilauea volcano (Hawaii) and at other active volcanoes. Monitoring the changes in emission rates of sulfur dioxide is very important for understanding volcano behavior and determining volcanic hazards.
Read Improving the accuracy of SO2 column densities and emission rates obtained from upward-looking UV-spectroscopic measurements of volcanic plumes by taking realistic radiative transfer into account, online.
USGS-CVO research geophysicist Jeff Wynn is an author on an article in Sea Technology magazine describing a USGS-developed technology to map the sub-seafloor for placer heavy minerals, buried wrecks, and trenched cables. Using the marine induced polarization technique, a ship tows an instrument array through the water or along the sea floor. An electrical signal is sent through the array and the secondary response is measured. The frequency of the response is diagnostic of certain deposits beneath the seafloor and could also be used to monitor biodegradation of an oil plume in real time in the deep ocean. Laboratory measurements indicate that the induced polarization technique can detect and map oil in the seawater column down to below 0.1% by volume. Read an excerpt from Induced Polarization for Subseafloor, Deep-Ocean Mapping, online.
Geologist Dave Ramsey and research collaborator Lee Siebert led groups of high school students from Kelso and Longview, Washington-area schools on interactive hikes of the Hummocks Trail at the Mount St. Helens National Volcanic Monument. The hikes were part of a STEM (Science, Technology, Engineering, and Math) initiative coordinated by the Southwest Washington Workforce Development Council and designed to give students experience with scientific investigations in the field and laboratory. On the hikes, students learned about the techniques used by scientists to understand the formation of the hummocks that occurred as a result of the massive debris avalanche of the May 18, 1980 eruption. For more information on exploring Mount St. Helens, visit the Mount St. Helens National Volcanic Monument webpage.
Glacier Peak is the most remote of the five active volcanoes in Washington State. It is not prominently visible from any major population center so its hazards tend to be over-looked. Since the end of the last ice age, Glacier Peak has produced some of the largest and most explosive eruptions in the state. CVO Geologist Jim Vallance is studying Glacier Peak’s tephra deposits to determine precisely when and how often the volcano has erupted, and the size of past eruptions. For more information, see the USGS Fact Sheet, Glacier Peak - history and hazards of a cascade volcano.
Diamond Craters is one of several young basalt lava fields dotting southeastern Oregon. Active between about 7320 and 7790 years ago (calibrated ages), the entire eruptive episode was less than 100 years in duration. Read more about Diamond Craters and the techniques scientists use to find the age of young lava flows and figure out how long eruptions last, in a new paper titled: Age and duration of volcanic activity at Diamond Craters, southeastern Oregon.
Scientists from CVO (VDAP) are working together with Indonesian scientists to support and enhance the Government of Indonesias' Center for Volcanology and Geologic Hazard Mitigation’s volcano monitoring and response capabilities. Five Indonesian scientists visited CVO in September, exchanging ideas and techniques for volcano monitoring and hazard assessment. The group observed hazards at Cascades volcanoes and traveled to Alaska to learn about how volcanic ash-aviation issues are handled in the US from colleagues at the Alaska Volcano Observatory, the Federal Aviation Administration and the National Weather Service. Indonesia is a country where more than 3.3 million people live very closely to active volcanoes. Through improved monitoring and warning systems, citizens can be warned of volcanic events to avoid harm. For more information on the U.S.-Indonesia efforts, read U.S. and Indonesia Partner to Reduce the Risk of Volcano Disasters and Save Lives. To learn about VDAP, see more at Volcano Disaster Assistance Program.
USGS Geologist Richard Waitt examines the deposits of pluvial Lake Chewaucan (Pleistocene), near Summer Lake, Oregon. The light colored horizontal lines are layers of ash from southern Cascade eruptions that fell on the lake, settled to the bottom and were covered by mud. This sequence represents a time period of roughly 50,000 years. Find out about ashfall hazards at Volcanic Ash: What it can do and how to prevent damage.
Recent articles in The Seattle Times discuss the completed maintenance of volcano monitoring sites at Mount Rainier and link to new photos of one of the highest remote stations in the Cascade Range. Read the stories online, Quake monitors on Mount Rainier ready and waiting, and Not just any day job: the view from 11,000 feet.
During the first week of September, scientists completed scheduled maintenance at five volcano monitoring stations between 7,000 and 11,000 feet on Mount Rainier. Work was completed by staff from the USGS Cascades Volcano Observatory (CVO) and Pacific Northwest Seismic Network (PNSN), with strong support from Mount Rainier National Park (MRNP). The stations provide continuous data streams that are critical for detecting signs of unrest at Mount Rainier. View Mount Rainier Monitoring information and a Photo Gallery of this work.
Researchers at CVO perform flume experiments to test mathematical models for interpreting and forecasting debris flow behavior. Up to 40 tons of sediment are placed behind a gate at the head of a 310-feet long flume, saturated with water and released. Data collection ports in the floor of the flume measure the forces due to particles sliding and colliding at the base of the flow, while photos and videos record surface effects. The experiments lead to development of technologies for mitigating debris flow hazards, including automated detection and warning systems and engineering countermeasures, to protect high-risk areas such as Mount St. Helens, Redoubt Volcano in Alaska, and Pinatubo Volcano in the Philippines. See past experiments at Video Documentation of Experiments at the USGS Debris-Flow Flume 1992–2006 (amended to include 2007–2009).
U.S. Geological Survey Cascades Volcano Observatory (CVO) personnel will be working in Mount Rainier National Park (MRNP) from September 4-7 to perform repairs, upgrades, and maintenance at 5 monitoring stations on the volcano. Installed in 2007-2008, the stations provide a continuous stream of real-time seismic and deformation measurements from one of the most hazardous volcanoes in the Cascade Range. A helicopter under contract to the National Park Service will assist with the high-elevation work (7,000 – 11,100 feet).
The fieldwork will be carried out by a team of 10-12 people from CVO, who will also support a University of Washington team performing similar maintenance on a remote seismic station operated by the Pacific Northwest Seismic Network (PNSN). The CVO stations, in conjunction with those from the PNSN seismic network, provide continuous data streams that are critical for detecting signs of unrest at Mount Rainier. In addition, data from the combined network is creating research opportunities for USGS and academic scientists who are investigating the inner workings of the volcano as well as studying several recent seismic swarms.
Recent articles in The Columbian describe the Mount St. Helens monitoring site upgrades and early preparations for the study of the magmatic system underneath the volcano. Read the stories online, Upgraded equipment aims to take St. Helens' pulse, and 2014 study of St. Helens magma system will be among world's largest.
CVO geologist Dave Ramsey stands on top of Wizard Island in the Crater Lake caldera, holding his Crater Lake Revealed poster. The poster, prepared from this same perspective, shows the geology of the lake floor from its deepest basins to shoreline. Mr. Ramsey was at Crater Lake to take part in an educational field trip on the geologic history and hazards of the area. Download the poster Crater Lake Revealed for your next trip to Crater Lake National Park.
Mount St. Helens is an active volcano, continuously monitored for earthquakes, ground deformation, erosion and debris flows. Clear, summer weather provides an opportunity to access remote monitoring sites for necessary repairs, to observe, quantify and track changes from previous years, and conduct new research. The image gallery, Mount St. Helens 2012 Fieldwork, highlights the summer work completed on the flanks of the volcano as well as in the crater.
On the northern flank of Mount St. Helens (Dogs Head lava dome in the background), Mike Clynne maps the surficial extent of a debris flow. Mount St. Helens has a rich and complex 300,000-year history of explosive eruptions, lava flows, dome building and debris flows. Mapping these deposits gives insight into the volcano’s eruptive past and provides a practical understanding of the geology of this area. To learn more about Mount St. Helen’s eruptive past, read Pre-1980 Eruptive History of Mount St. Helens, Washington.
While conducting routine field work at Mount St. Helens, 13-14 mountain goats were spotted one-half mile upstream of Loowit Falls. The goats crossed the Loowit canyon and headed east, climbing rough volcanic terrain to disappear around the eastern flank of the mountain. Goats have become year-round residents at the volcano, likely traveling from nearby Mount Adams or Goat Rocks to find new habitat. Read about mountain goat ecology and where to view goats at the Washington Department of Fish and Wildlife conservation webpage.
On the weekend of July 28, hikers in Canyon Creek Meadows near Three Fingered Jack (central Oregon Cascades) were surprised to find boulders and mud coating the west end of the meadow. The deposits are from a recent debris flow caused by a partial breach of a lake dammed by a young glacial moraine at the snout of tiny “Jack Glacier.” The sudden outflow from the lake incorporated rocks, sand, and mud that was deposited in a bouldery fan at the foot of the moraine with muddy water flooding the meadow and flowing into Canyon Creek. The trigger for the breach is not yet known. Such events, including two in Canyon Creek Meadows during the latter half of the 20th century, have been documented at numerous moraine-dammed lakes in the Mount Jefferson and Three Sisters area. To learn more, read Debris flows from failures of Neoglacial-age moraine dams in the Three Sisters and Mount Jefferson wilderness areas, Oregon.
Christoph Kern sets up a UV spectrometer to detect volcanic gases rising from fumaroles at Crater Rock on Mount Hood. The instrument measures the spectrum of light passing through volcanic gas and identifies individual gas species by their unique absorption “fingerprints”. The equipment is sensitive enough to detect mixing ratios of less than a part per million (one molecule of volcanic gas per one million molecules of air). In this case, the spectrometer detected low amounts of sulfur dioxide gas, similar to those found in measurements taken here last year. For more information, visit the Volcano Emission Project.
Marc Biundo and Bryan Holmes climb to Camp Schurman, at the base of Steamboat Prow on Mount Rainier (elevation 9500 feet), to check GPS equipment, troubleshoot radio telemetry, and conduct radio tests to new receiver sites off of the volcano. A Global Positioning System (GPS) was installed at the climbing hut in 2007 to monitor subtle movements of the volcano. The data shows the mountain moves several millimeters per year to the north and east, following a regional tectonic trend. Because of its location near to large population centers and the nature of the potential hazards, the USGS installed monitoring networks to be able to detect the onset of volcanic activity at Mount Rainier at the earliest possible moment. To learn more, visit the Pacific Northwest GPS Monitoring Network.
Workshop participants Tiffany Fuller and Lucas Jones reach Pinnacle Saddle, south of Mount Rainier, during an afternoon session of experiential learning. Each year, personnel from CVO and the National Park Service provide a week-long course for teachers to learn about volcanic processes, hazards, and human-volcano interactions while exploring Mount Rainier National Park. The workshop materials, which include more than 30 student activities and a field guide to geological sites of interest within the Park, is designed for middle school teachers interested in teaching about this and other Cascade peaks. To browse the activities and learn more, visit Living with a Volcano in Your Backyard: An Educator’s Guide to Mount Rainier.
A scientist (lower center) walks along the leading edge of rock debris carried downslope by Crater Glacier, documenting evidence of glacial advance into the Loowit stream channel. The glacier continues to advance at approximately 10 cm per day (about the length of a computer mouse) although the rate of advance has slowed since the 2004-2008 lava dome building ended. To learn more about Crater Glacier and see an animation of the glacier’s movement, visit Photographic Documentation of the Evolution of Crater Glacier, Mount St. Helens, Washington, September 2006–November 2009.
As snow melts from the upper reaches of Mount St. Helens, CVO scientists access remote monitoring sites to repair and replace equipment damaged by harsh winter weather. Here, the team refurbishes an acoustic flow monitor (AFM) located above the Loowit River. The AFM was designed by the USGS-CVO to detect and monitor debris flows through ground vibrations and transmit the data in real-time. AFMs are a key component of early warning systems in valleys threatened by such flows. To learn more, read about Hydrologic Monitoring of Volcanoes.
Newberry Volcano is the first of the CVO volcanoes to showcase the updated website design. The new web pages include more information about the large central Oregon volcano than the old CVO website offered. We hope you enjoy the new look and enhanced information!
Outside of Portland, Oregon, the Marmot Dam blocked the Sandy River for more than 90 years. A combination of economic and environmental issues resulted in the removal of the dam in 2007, allowing the river to flow freely over its entire length. In the hours, days and months following the breach, the USGS monitored the erosion, transport, and deposition of sediment downstream. The energetic Sandy River responded rapidly, removing a large amount of reservoir sediment in the first year. The erosion rate and channel widening diminished with time. A newly published USGS report, in collaboration with scientists at Federal agencies, academic institutions, and private companies, describes the two-year transition along the Sandy River.
How did an eruption in Alaska, 1200 miles from Seattle, affect life in the Pacific Northwest 100 years ago this week? Learn how the June 6, 1912 eruption of Novarupta, near Katmai, Alaska affected life in the Pacific Northwest, and how future volcanic ash fall can disrupt our lives.
May 18, 2012 marks the 32nd anniversary of Mount St. Helens' catastrophic eruption, the first volcanic eruption in the conterminous United States since the 1915 eruption of California's Lassen Peak. View archive photos of Mount St. Helens. Read a summary of events. Learn about the 1980 eruptions. Download a 2012 panorama of Mount St. Helens, and modern photos of the volcano and ongoing monitoring.
View article in The Columbian newspaper about work of the USGS Cascades Volcano Observatory.
Following two weeks of fieldwork, a three person team from the USAID-USGS Volcano Disaster Assistance Program (VDAP) has returned from Colombia where, at the request of the Servicio Geológico Colombiano (SGC; Geological Survey of Colombia), they were working to support the monitoring and eruption forecasting efforts at Nevado del Ruiz volcano. Photo shows USGS and SGC personnel working at a lahar (volcanic debris flow) detection and warning instrument site high on the flanks of Ruiz. An eruption from Nevado del Ruiz on November 13, 1985 caused over 23,000 deaths as several towns were overrun by rapidly moving volcanic debris flows. Recently, Ruiz has been showing signs that it may erupt again. To learn more about VDAP, which is based at the USGS Cascades Volcano Observatory, please visit the VDAP website.
USGS will conduct a variety of volcano-related trainings for emergency managers, aviators, health care personnel, park interpreters, and school students. See volcano preparedness materials highlighted on the 'In-Focus' web page of Washington Military Department’s Emergency Management Division. Find volcano information and educational opportunities at this website. Read the news release.
Three USGS volcanologists from the Cascades Volcano Observatory are working with our counterpart organization, the Center for Volcanology and Geological Hazards Mitigation, to install real-time GPS monitoring on Agung Volcano and to evaluate recent seismicity. Recent satellite measurements show that the volcano has been slowly inflating over the past several years. Agung is an active and dangerous volcano located on Bali, which in 1963 produced an eruption that killed more than 1000 people. The 1963 Agung eruption was similar in magnitude to the 1980 eruption of Mount St. Helens. Monitoring infrastructure enhancement is part of our Volcano Disaster Assistance Program, a partnership of the USGS and the U.S. Agency for International Development. In the photo a solar-powered GPS installation on Agung’s flanks is nearing completion. Data from this and other installations will be used to continuously measure movements of the volcano flanks and will be used with seismic and other data to provide forecasts of eruptive activity.
On April 20, a three person team from the USAID-USGS Volcano Disaster Assistance Program (VDAP) is traveling to Colombia at the request of the Instituto Colombiano de Geologia y Mineria (INGEOMINAS), to support volcano monitoring and data analysis activities at Nevado del Ruiz volcano, which has been showing signs that it may erupt soon. An eruption from Nevado del Ruiz on November 13, 1985 caused over 23,000 deaths as several towns were overrun by rapidly moving volcanic debris flows. To learn more about VDAP, which is based at the USGS Cascades Volcano Observatory, please visit the VDAP website.
Wading into the North Fork Toutle River (near Mount St. Helens, Washington), USGS Hydrotech Tami Christianson collects a water and sediment sample from mid-stream. Erosion of the huge debris avalanche deposit emplaced on May 18, 1980, continues to generate high sediment loads. Some is trapped behind the U.S. Army Corps of Engineers Sediment Retention Structure (SRS), but increasing amounts are bypassing the structure and endangering fish habitat and increasing flood risks to downstream communities. Sampling above and below the SRS is done periodically to evaluate the performance of the structure.
CVO scientists Richard Waitt and David Ramsey are authors on a newly published geospatial (GIS) database of recent volcanic deposits on Augustine Volcano, Alaska. The publication, McIntire, J., Ramsey, D.W., Thoms, E., Waitt, R.B., and Beget, J.E., 2012, Database for volcanic processes and geology of Augustine Volcano, Alaska: U.S. Geological Survey Data Series 677 (database for USGS Professional Paper 1762, by Waitt and Beget), is available from the USGS publications website. Augustine is a frequently active island volcano in Cook Inlet.
Educators, read this announcement about Conversations with Scientists webinars. Programs are intended for middle and high school classrooms. The registration deadline has been extended through March 27th for the March 29th Crater Lake program.
Starting at approximately 22:00 pm PST on 7 March 2012, a small swarm of earthquakes has been occurring near Mount Hood. The earthquakes locate approximately 4 miles south-southwest of the summit of the volcano (~1 mile east of Government Camp) at depths of 2-4 miles. Between 22:00 PST March 7 and 16:00 PST March 9, over a dozen small earthquakes have been located by the Pacific Northwest Seismic Network (PNSN), with magnitudes ranging from 0.0 to 1.7. Typically, several earthquake swarms occur each year at Mount Hood, with some lasting for hours, others lasting for days to weeks. The March 7-9 swarm locates in roughly the same area as previous swarms, including swarms that occurred in February 1998 and September 2001. It is located 2-3 miles west of a swarm that occurred 22-23 February 2012.
For more details about Hood seismicity, visit the PNSN Mount Hood web page. For background information about swarms at Mount Hood, visit the PNSN web site for an excellent blog posting at PNSN Hood swarm blog
During August 2011, scientists and volunteers from the USGS Cascades Volcano Observatory (CVO) installed eight new real-time seismic and deformation (GPS) volcano monitoring stations around Newberry Volcano.
Over the last several months scientists at USGS-CVO and PNSN have been studying data from these new stations. They now have an adequate baseline understanding of activity at Newberry Volcano against which to compare future signs of unrest.
An Information Statement about the monitoring network was issued today.
The USGS and the US Forest Service have published a fact sheet about Newberry Volcano in Central Oregon. Learn about the geologic history, diverse styles of volcanism, volcanic hazards, monitoring and research at the largest volcano in the Cascades by reading the fact sheet on-line.
The U.S. ranks as one of the top countries in the world in the number of young, active volcanoes. The spectrum of volcanism includes explosive stratovolcanoes, effusive shield volcanoes, and restless calderas. Between 1980 and 2008, 43 volcanoes within the U.S. produced 95 eruptions and 32 episodes of unrest, the majority of which occurred in Alaska. A description and chronology of these eruptions and periods of unrest and a list of published literature is available at the USGS Publications Warehouse.
As the understanding of volcanic activity and hazards has grown over the years, so have the extent and types of monitoring networks and techniques available to detect early signs of anomalous volcanic behavior. This increased capability is providing us with a more accurate gauge of volcanic activity in the U.S. and at volcanoes monitored by CVO.
Mount St. Helens climbing permits are available for the 2012 summer season. U.S. Forest Service climbing permits are administered through the Mount St. Helens Institute which also offers a variety of educational programs related to Mount St. Helens. For more information, visit the U.S. Forest Service or Mount St. Helens Institute websites.
Beginning at approximately 12:30 pm PST on 23 February 2012 a small swarm of earthquakes occurred at Mount Hood. The earthquakes are approximately 4 miles south southeast of the summit of the volcano, and are occurring at depths of 3-5 miles. Between 12:30 PST Thursday and 8:00 PST Friday, more than 25 small earthquakes were located by the Pacific Northwest Seismic Network (PNSN), with magnitudes ranging from 0.1 to 1.7. Over the last 24 hours (through Saturday late-morning) no additional earthquakes occurred. Typically, several earthquake swarms occur each year at Mount Hood, with some lasting for hours, others lasting for days to weeks. The February 23-24 swarm locates in roughly the same area as previous swarms.
For more details about this swarm, visit the PNSN web site for an excellent blog posting about the swarm at PNSN blog as well as their Mount Hood seismicity map with locations of the swarm events at PNSN Mount Hood page
Beginning at approximately 12:30 pm PST on 23 February 2012 a small swarm of earthquakes occurred at Mount Hood. The earthquakes are approximately 4 miles south southeast of the summit of the volcano, and are occurring at depths of 3-5 miles. Between 12:30 and 2:30 there had been 15 small earthquakes ranging in magnitude from -0.2 to 1.8. Typically, several earthquake swarms occur each year at Mount Hood and this swarm is located in the same area as other previous swarms.
To see a map of where the earthquakes are occurring please visit the Pacific Northwest Seismic Network (PNSN) web site: PNSN
We are currently upgrading our website to provide a new look and improved functionality. When completed, the website will offer streamlined access to information about volcano hazards and preparedness, maps, images, monitoring data, and volcano histories.
Many of the links on this new home page will take you into the original CVO website, and these will gradually change as content is updated. Check back frequently.