Geology topics
Publications and source records attributed to Carolyn L. Driedger.
This poster provides an overview of Mount St. Helens’ eruption history and emphasizes the continuous transformation of the volcanic landscape and its ecosystems. After each eruption, the landscape and ecosystems are not so much restored as they are morphed into new forms and patterns.
Mount St. Helens was once enjoyed for its serene beauty and was considered one of America’s most majestic volcanoes because of its perfect cone shape, similar to Japan’s beloved Mount Fuji. Nearby residents assumed that the mountain was solid and enduring. That perception changed during the early spring of 1980. Then, on May 18, 1980, following 2 months of earthquakes and small explosions, the volcano’s over-steepened north flank collapsed in a colossal landslide and triggered a near-horizontal blast, followed by a powerful vertical eruption. The high-speed, rock-filled, and gas-charged blast quickly evolved into a gravitationally driven pyroclastic flow, which leveled millions of trees, stripped them of their branches and bark, and scoured soil from bedrock. The vertical eruption that followed fed a towering plume of ash for more than 9 hours. Winds carried the ash from the volcano and deposited it hundreds of miles away. Lahars (volcanic mudflows) buried river valleys. These catastrophic events caused the worst volcanic disaster in the recorded history of the conterminous United States. The events violently transformed Mount St. Helens and left a lasting impression on the hearts and minds of people living in the Pacific Northwest and beyond.
During the 1980 eruption of Mount St. Helens, the occurrence of floods and mudflows made apparent a need to assess mudflow hazards on other Cascade volcanoes. A basic requirement for such analysis is information about the volume and distribution of snow and ice on these volcanoes. An analysis was made of the volume-estimation methods developed by previous authors and a volume estimation method was developed for use in the Cascade Range. A radio echo-sounder, carried in a backpack, was used to make point measurements of ice thickness on major glaciers of four Cascade volcanoes (Mount Rainier, Washington; Mount Hood and the Three Sisters, Oregon; and Mount Shasta, California). These data were used to generate ice-thickness maps and bedrock topographic maps for developing and testing volume-estimation methods. Subsequently, the methods were applied to the unmeasured glaciers on those mountains and, as a test of the geographical extent of applicability, to glaciers beyond the Cascades having measured volumes. Two empirical relationships were required in order to predict volumes for all the glaciers. Generally, for glaciers less than 2.6 km in length, volume was found to be estimated best by using glacier area, raised to a power. For longer glaciers, volume was found to be estimated best by using a power law relationship, including slope and shear stress. The necessary variables can be estimated from topographic maps and aerial photographs.
During the twentieth century, glacial outburst floods have been the most destructive natural events on Mount Rainier, a stratovolcano in the Cascade Range in Washington State, U.S.A. In the period between 1930 and 1980 numerous floods were reported from five glaciers on the mountain, most of which flowed from Nisqually, Kautz, or South Tahoma Glaciers on its southern flank. Such floods threaten lives and property because they occur without warning and quickly mobilize the loose volcanic debris into debris flows. A monitoring program was begun in 1987 which was designed to measure the dimensions and timing of outburst floods, but this has been unsuccessful because no floods have yet occurred on the monitored streams. Four floods did burst from South Tahoma Glacier that was unmonitored, but in spite of this they have been useful in providing evidence of flood storage and release mechanisms. All flood volumes were found to be of approximately similar orders of magnitude, of 1 × 10 5 m 3 of water, indicating that all floods probably had similar mechanisms for storage and release of water. Hydraulic pressure considerations indicate that such a large volume of flood water would be stored at the bed of the glacier rather than in isolated englacial cavities. The stepped bedrock terrain provides an ideal setting for the formation of subglacial cavities capable of storing the volumes of flood water noted.
At least 170 volcanoes in 12 States and 2 territories have erupted in the past 12,000 years and have the potential to erupt again. Consequences of eruptions from U.S. volcanoes can extend far beyond the volcano’s immediate area. Many aspects of our daily life are vulnerable to volcano hazards, including air travel, regional power generation and transmission infrastructure, interstate transportation, port facilities, communications infrastructure, and public health. The U.S. Geological Survey has the Federal responsibility to issue timely warnings of potential volcanic activity to the affected populace and civil authorities. The Volcano Hazards Program (VHP) is funded to carry out that mission and does so through a combination of volcano monitoring, short-term warnings, research on how volcanoes work, and community education and outreach.
Introduction Natural scientists, like many other experts, face challenges when communicating to people outside their fields of expertise. This is especially true when they try to communicate to those whose background, knowledge, and experience are far distant from that field of expertise. At a recent workshop, experts in risk communication offered insights into the communication challenges of probabilistic hazard products, suggested tips, and shared their strategies for making products that a targeted audience can understand and use. Although the workshop was held to broaden the understanding and use of the U.S. Geological Survey (USGS) National Seismic Hazard Maps (NSHM), the workshop outcomes presented in this report can benefit anyone who develops products based on technical information. On the basis of research and practice into how people think, use tools, make decisions, and understand scientific/technical information, the social and behavioral scientists, marketers, and social-impact designers at the NSHM workshop provided remarkably consistent guidelines to develop successful science products, such as text, maps, and other products. In this report the guidelines are numbered for clarity, but they can be applied repeatedly, piecemeal, or out of order to fit each project and your resources.
Lahars are rapid flows of mud-rock slurries that can occur without warning and catastrophically impact areas more than 100 km downstream of source volcanoes. Strategies to mitigate the potential for damage or loss from lahars fall into four basic categories: (1) avoidance of lahar hazards through land-use planning; (2) modification of lahar hazards through engineered protection structures; (3) lahar warning systems to enable evacuations; and (4) effective response to and recovery from lahars when they do occur. Successful application of any of these strategies requires an accurate understanding and assessment of the hazard, an understanding of the applicability and limitations of the strategy, and thorough planning. The human and institutional components leading to successful application can be even more important: engagement of all stakeholders in hazard education and risk-reduction planning; good communication of hazard and risk information among scientists, emergency managers, elected officials, and the at-risk public during crisis and non-crisis periods; sustained response training; and adequate funding for risk-reduction efforts. This paper reviews a number of methods for lahar-hazard risk reduction, examines the limitations and tradeoffs, and provides real-world examples of their application in the U.S. Pacific Northwest and in other volcanic regions of the world. An overriding theme is that lahar-hazard risk reduction cannot be effectively accomplished without the active, impartial involvement of volcano scientists, who are willing to assume educational, interpretive, and advisory roles to work in partnership with elected officials, emergency managers, and vulnerable communities.
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. An enormous lava dome grew episodically in the crater until 1986, when the volcano became relatively quiet. A new glacier grew in the crater, wrapping around and partly burying the lava dome. From 1987 to 2003, sporadic earthquake swarms and small steam explosions indicated that magma (molten rock) was being replenished deep underground. In 2004, steam-and-ash explosions heralded the start of another eruption. A quieter phase of continuous lava extrusion followed and lasted until 2008, building a new dome and doubling the volume of lava on the crater floor. Scientists with the U.S. Geological Survey and University of Washington’s Pacific Northwest Seismograph Network maintain constant watch for signs of renewed activity at Mount St. Helens and other Cascade volcanoes. Now is an ideal time for both actual and virtual visitors to Mount St. Helens to learn more about dramatic changes taking place on and beneath this active volcano.
A functional tabletop exercise was run on November 14-15, 2011 in Salt Lake City, Utah, to test crisis response capabilities, communication protocols, and decision-making by the staff of the multi-agency Yellowstone Volcano Observatory (YVO) as they reacted to a hypothetical exercise scenario of accelerating volcanic unrest at the Yellowstone caldera. The exercise simulated a rapid build-up of seismic activity, ground deformation, and hot-spring water-chemistry and temperature anomalies that culminated in a small- to moderate-size phreatomagmatic eruption within Yellowstone National Park. The YVO scientific team's responses to the unfolding events in the scenario and to simulated requests for information by stakeholders and the media were assessed by (a) the exercise organizers; (b) several non-YVO scientists, who observed and queried participants, and took notes throughout the exercise; and (c) the participants themselves, who kept logs of their actions during the exercise and later participated in a group debriefing session and filled out detailed questionnaires. These evaluations were tabulated, interpreted, and summarized for this report, and on the basis of this information, recommendations have been made. Overall, the YVO teams performed their jobs very well. The exercise revealed that YVO scientists were able to successfully provide critical hazards information, issue information statements, and appropriately raise alert levels during a fast-moving crisis. Based on the exercise, it is recommended that several measures be taken to increase YVO effectiveness during a crisis: 1. Improve role clarification within and between YVO science teams. 2. Improve communications tools and protocols for data-sharing and consensus-building among YVO scientists, who are geographically and administratively dispersed among various institutions across the United States. 3. Familiarize YVO staff with Incident Command System (ICS) procedures and protocols, and provide more in-depth training to appropriate staff members, as needed. 4. Train all science team members in the use of all analytical and computational tools available to them, in order to maximize effectiveness of teams in tracking and interpreting possible accelerating unrest at Yellowstone. Desirable pre-crisis preparations include: (a) updating a catalog of existing map and information products (and identifying additional products) that would be helpful during a crisis; (b) creating "to do" lists of early-crisis tasks for each scientific team; (c) coordinating radio frequencies among partner agencies; and (d) brief training on and promotion of the internal YVO Web log as a repository for scientific observations, data, photographs, and other material to be shared among YVO scientific teams during a crisis. This exercise was designed as an opportunity to practice response to a fast-developing volcano crisis and to test for organizational and procedural weaknesses that could emerge during a real crisis. This report is based upon the observations of the exercise organizers during the one-day exercise and upon written evaluations by the participants. It does not attempt to evaluate any other aspect of YVO or the scientific expertise of any of the highly competent YVO staff. Participants unanimously found the exercise to be helpful for improving their response capabilities, and it is our hope that the report will be a starting point for internal discussions that will make YVO even better-prepared for some future volcano crisis.
Majestic Mount Rainier soars almost 3 miles (14,410 feet) above sea level and looms over the expanding suburbs of Seattle and Tacoma, Washington. Each year almost two million visitors come to Mount Rainier National Park to admire the volcano and its glaciers, alpine meadows, and forested ridges. However, the volcano's beauty is deceptive - U.S. Geological Survey (USGS) research shows that Mount Rainier is one of our Nation's most dangerous volcanoes. It has been the source of countless eruptions and volcanic mudflows (lahars) that have surged down valleys on its flanks and buried broad areas now densely populated. To help people live more safely with the volcano, USGS scientists are working closely with local communities, emergency managers, and the National Park Service.
Volcanoes have been erupting in the Cascade Range for over 500,000 years. During the past 4,000 years eruptions have occurred at an average rate of about 2 per century. This chart shows 13 volcanoes on a map of Washington, Oregon, and northern California and time lines for each showing the ages of their eruptions.
Most volcano hazards are associated with eruptions. However, some hazards, such as lahars and debris avalanches, can occur even when a volcano is not erupting.
The 2004 reawakening of Mount St. Helens quickly caught the attention of government agencies as well as the international news media and the public. Immediate concerns focused on a repeat of the catastrophic landslide and blast event of May 18, 1980, which remains a vivid memory for many individuals. Within several days of the onset of accelerating seismicity, media inquiries increased exponentially. Personnel at the U.S. Geological Survey, the Pacific Northwest Seismic Network, and the Gifford Pinchot National Forest soon handled hundreds of press inquiries and held several press briefings per day. About one week into the event, a Joint Information Center was established to help maintain a consistent hazard message and to provide a centralized information source about volcanic activity, hazards, area closures, and media briefings. Scientists, public-affairs specialists, and personnel from emergency-management, health, public-safety, and land-management agencies answered phones, helped in press briefings and interviews, and managed media access to colleagues working on science and safety issues. For scientists, in addition to managing the cycle of daily fieldwork, challenges included (1) balancing accurate interpretations of data under crisis conditions with the need to share information quickly, (2) articulating uncertainties for a variety of volcanic scenarios, (3) minimizing scientific jargon, and (4) frequently updating and effectively distributing talking points. Success of hazard information management during a volcanic crisis depends largely on scientists’ clarity of communication and thorough preplanning among interagency partners. All parties must commit to after-action evaluation and improvement of communication plans, incorporating lessons learned during each event.
Mount St. Helens has erupted more frequently than any other volcano in the Cascade Range during the past 4,000 years. The volcano has exhibited a variety of eruption styles?explosive eruptions of pumice and ash, slow but continuous extrusions of viscous lava, and eruptions of fluid lava. Evidence of the volcano?s older eruptions is recorded in the rocks that build and the deposits that flank the mountain. Eruptions at Mount St. Helens over the past three decades serve as reminders of the powerful geologic forces that are reshaping the landscape of the Pacific Northwest. On May 18, 1980, a massive landslide and catastrophic explosive eruption tore away 2.7 cubic kilometers of the mountain and opened a gaping, north-facing crater. Lahars flowed more than 120 kilometers downstream, destroying bridges, roads, and buildings. Ash from the eruption fell as far away as western South Dakota. Reconstruction of the volcano began almost immediately. Between 1980 and 1986, 80 million cubic meters of viscous lava extruded episodically onto the crater floor, sometimes accompanied by minor explosions and small lahars. A lava dome grew to a height of 267 meters, taller than the highest buildings in the nearby city of Portland, Oregon. Crater Glacier formed in the deeply shaded niche between the 1980-86 lava dome and the south crater wall. Its tongues of ice flowed around the east and west sides of the dome. Between 1989 and 1991, multiple explosions of steam and ash rocked the volcano, possibly a result of infiltrating rainfall being heated in the still-hot interior of the dome and underlying crater floor. In September 2004, rising magma caused earthquake swarms and deformation of the crater floor and glacier, which indicated that Mount St. Helens might erupt again soon. On October 1, 2004, a steam and ash explosion signaled the beginning of a new phase of eruptive activity at the volcano. On October 11, hot rock reached the surface and began building a new lava dome immediately south of the 1980-86 lava dome. The erupting lava cleaved Crater Glacier in half and bulldozed it aside, causing thickening, crevassing, and rapid northward advance of the glacier?s east and west arms. Intermittent steam and ash explosions, some generating plumes that rose up to 11 kilometers, preceded and accompanied extrusion of the new lava dome, but ceased by early 2005. As the new dome grew, a series of large fins or spines of hot lava rose, some more than 100 meters high, and then crumbled producing sometimes spectacular rock falls. The largest of these rock falls generated dust or steam plumes that rose high above the crater rim. By February 2006, the new dome had grown to a volume similar to that of the 1980-86 lava dome; and by July 2007, the new dome had grown to a volume of 93 million cubic meters, exceeding the volume of the 1980-86 lava dome. The height of the new dome also exceeded that of the 1980-86 lava dome, and at its highest point (before collapse in 2005) reached to within 2 meters of the lowest point on the south crater rim. At this height, the new dome was taller than the Empire State Building in New York City. The new lava dome initially grew very quickly, at rates of 2 to 3 cubic meters (one small dump truck load) per second. If it had continued to grow at these rates for about 100 years, it would have replaced the volume of rock removed from the volcano during the May 18, 1980, eruption. However, the lava extrusion rate slowed throughout the eruption, and, by July 2007, it was oozing at a rate of 0.1 cubic meters per second. At that rate, it would take over 700 years to replace the volume of rock lost in 1980. Lava dome extrusion has continued into early 2008.
The importance of investing in monitoring, mitigation, and preparedness before natural hazards occur has been amply demonstrated by recent disasters such as the Indian Ocean Tsunami in December 2004 and Hurricane Katrina in August 2005. Playing catch-up with hazardous natural phenomena such as these limits our ability to work with public officials and the public to lessen adverse impacts. With respect to volcanic activity, the starting point of effective pre-event mitigation is monitoring capability sufficient to detect and diagnose precursory unrest so that communities at risk have reliable information and sufficient time to respond to hazards with which they may be confronted. Recognizing that many potentially dangerous U.S. volcanoes have inadequate or no ground-based monitoring, the U.S Geological Survey (USGS) Volcano Hazards Program (VHP) and partners recently evaluated U.S. volcano-monitoring capabilities and published 'An Assessment of Volcanic Threat and Monitoring Capabilities in the United States: Framework for a National Volcano Early Warning System (NVEWS).' Results of the NVEWS volcanic threat and monitoring assessment are being used to guide long-term improvements to the national volcano-monitoring infrastructure operated by the USGS and affiliated groups. The NVEWS report identified the need to convene a workshop of a broad group of stakeholders--such as representatives of emergency- and land-management agencies at the Federal, State, and local levels and the aviation sector--to solicit input about implementation of NVEWS and their specific information requirements. Accordingly, an NVEWS Stakeholders Workshop was held in Portland, Oregon, on 22-23 February 2006. A summary of the workshop is presented in this document.
Today’s residents, as well as residents of centuries past, consider Mount Rainier “the spiritual and cultural icon of the Pacific Northwest.” As a backdrop for many of the State’s residents, Mount Rainier offers beauty, solace, inspiration, and challenge. The mountain sets the daily mood for thousands of people who gaze at and respect it. There is no mistaking this object of admiration when people smile and remark that, “the mountain is out!” Yet, the origin of Mount Rainier, formed by volcanic processes and now heavily laden with snow and ice, remains an enigma to many admirers. During the 1980s, volcanologists from around the world voted Mount Rainier as one of 17 volcanoes most worthy of additional study because of the hazard potential to large population centers nearby. Subsequent research indicates that Mount Rainier, though quiet since the nineteenth century, is very much an “active volcano” with potential to erupt again and disrupt the life of Pacific Northwest residents. Following days to months or more of warning, Mount Rainier could erupt lava and ash and melt snow and ice to form lahars (volcanic mudflows). Or, Mount Rainier could simply warm up briefly, jolt us from our apathy, and then return to slumber for many more years. Until such time, the mountain is ours to explore. Living with a Volcano in Your Backyard—An Educator’s Guide with Emphasis on Mount Rainier invites educators and their students to learn what scientists are discovering about Mount Rainier’s past, to explore its slopes during this period of quiescence, and to plan future responses to volcanic unrest. Mount Rainier National Park is a unique classroom, rich in resources for observing geologic change. The park staff encourages safe and knowledgeable use by educators and students and their families. The National Park Service and the U.S. Geological Survey’s Volcano Hazards Program (USGS-VHP) support development and publication of this educator’s guide as part of their mission to educate the public about volcanoes. The USGS-VHP studies the dynamics of volcanoes, investigates eruption histories, develops hazard assessments, monitors volcano-related activity, and collaborates with local officials to lower the risk of disruption when volcanoes become restless.
The Seattle, Washington, area is known for its livability and its magnificent natural setting. The city and nearby communities are surrounded by an abundance of rivers and lakes and by the bays of Puget Sound. Two majestic mountain ranges, the Olympics and the Cascades, rim the region. These splendid natural features are products of dynamic forces -- landslides, earthquakes, tsunamis, glaciers, volcanoes, and floods. The same processes that formed this beautiful landscape pose hazards to the ever-growing population of the region. To maintain the Seattle area's livability, public and private policymakers must learn to manage the area's vulnerability to natural hazards to protect its three million residents from loss and damage from future disasters. The U.S. Geological Survey (USGS) is working with other Federal and State agencies, the city of Seattle, and other local governments to provide necessary scientific information that will help communities manage the natural hazards. This information will be useful in planning future development, siting public facilities and businesses, and developing effective emergency plans. -- Gori, et.al., 1999
Mount Rainier is an active volcano reaching more than 2.7 miles (14,410 feet) above sea level. Its majestic edifice looms over expanding suburbs in the valleys that lead to nearby Puget Sound. USGS research over the last several decades indicates that Mount Rainier has been the source of many volcanic mudflows (lahars) that buried areas now densely populated. Now the USGS is working cooperatively with local communities to help people live more safely with the volcano.