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Thomas C. Pierson

Publications and source records attributed to Thomas C. Pierson.

At least 19 recordsLinked to original sources
USGS2026

Getting the story straight: Common misconceptions around volcanoes and eruptions with case studies of recent events

The ability to rapidly disseminate scientific knowledge across the world has never been greater. This is paralleled by the ability of rumors to spread equally far and fast. Popular misconceptions can take root and, without correction, take on the appearance of facts. Commonly misunderstood topics include those with attention-grabbing phrasing (e.g. “Pacific Ring of Fire”, “supervolcanoes”, or “mega-tsunamis”), the intersection of volcanic research with high-profile science topics (climate or human health), aspirational science goals (eruption forecasts), and basic terminology (volcanic ash versus smoke, or magma “chambers”). In this paper, we describe eighteen misconceptions grouped in six themes (seismology, volcanoes and climate, systems and structures, volcanic hazards, timescales, photographs and footage) commonly encountered by volcanologists who are actively engaging with the public and media both during and between eruptions. Each misconception description is accompanied by takeaway points and summaries of recent research to assist the reader with the information necessary to describe the issues. Finally, we present seven case studies where incorrect information was widely shared and counteracted at well-known volcanoes and recent eruptions at Mount Agung (Bali, Indonesia), Mount Etna (Sicily, Italy), Kīlauea (Hawaii, U.S.A.), Tajogaite (La Palma, Spain), La Soufrière (St. Vincent), Taal Volcano (Philippines), and Yellowstone caldera (U.S.A.). This work is intended to help both volcanologists and non-specialists get the story straight, and to effectively communicate processes and scales of volcanism and volcanic hazards, impacts, and risks.

Journal of Applied Volcanology↗
USGS2019

When volcanoes fall down—Catastrophic collapse and debris avalanches

Despite their seeming permanence, volcanoes are prone to catastrophic collapse that can affect vast areas in a matter of minutes. Large collapses begin as gigantic landslides that quickly transform to debris avalanches—chaotically tumbling masses of rock debris that can sweep downslope at extremely high velocities, inundating areas far beyond the volcano. Rapid burial by the debris avalanches themselves, associated eruptions and lahars (volcanic mudflows), and inundation by tsunamis triggered when avalanches impact bodies of water can all cause widespread devastation to people and property.

Fact Sheet↗
USGS2018

Geologic field-trip guide of volcaniclastic sediments from snow- and ice-capped volcanoes—Mount St. Helens, Washington, and Mount Hood, Oregon

This field guide for the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) Scientific Assembly 2017 focuses on volcaniclastic sediments from Mount St. Helens in Washington and Mount Hood in Oregon. The trip spends four days in the field and includes nine stops at each volcano. For completeness, this guidebook also includes sixteen optional stops in the Mount St. Helens area and three in the Mount Hood area. These two volcanoes provide excellent depositional records of the broad spectrum of volcanic hazards that involve the flow or fall of volcaniclastic particles. At the field-trip stops we will contrast and compare the different types of deposits—sediments that can be frustratingly difficult to distinguish from one another. Correct identification of deposit origin leads to a better understanding of hazards that can impact vulnerable communities at particular volcanoes. During this four-day field trip, we will spend two days in the Mount St. Helens area and two days near Mount Hood. On the first day, we will visit debris-avalanche and lahar deposits in the Toutle River valley in Washington. The second day will focus on pyroclastic density current, pyroclastic-fall, lahar, and volcano-fluvial deposits in the Lewis River drainage system near Mount St. Helens. On the third day, we will visit hyaloclastites, glacial tills, and other diamicts in the Hood River and Sandy River basins near Mount Hood. The fourth and final day will focus on distal lahar and volcano-fluvial deposits downstream of Mount Hood. What follows is an in-depth introduction to the deposits studied on this field trip. We provide criteria that are observable in the field to aid in differentiating between pyroclastic density current, pyroclastic-fall, debris-avalanche, lahar, water-flood, and glacial deposits. We also introduce the Holocene eruptive histories of Mount St. Helens and Mount Hood and discuss the processes responsible for deposit emplacement. Field-trip stops and features of interest along the route are described in detail in a road log that provides daily cumulative mileage.

Oregon, Washington↗
USGS2018

Lahar—River of volcanic mud and debris

Lahar, an Indonesian word for volcanic mudflow, is a mixture of water, mud, and volcanic rock flowing swiftly along a channel draining a volcano. Lahars can form during or after eruptions, or even during periods of inactivity. They are among the greatest threats volcanoes pose to people and property. Lahars can occur with little to no warning, and may travel great distances at high speeds, destroying or burying everything in their paths. Lahars form in many ways. They commonly occur when eruptions melt snow and ice on snow-clad volcanoes; when rains fall on steep slopes covered with fresh volcanic ash; when crater lakes, volcano glaciers or lakes dammed by volcanic debris suddenly release water; and when volcanic landslides evolve into flowing debris. Lahars are especially likely to occur at erupting or recently active volcanoes. Because lahars are so hazardous, U.S. Geological Survey scientists pay them close attention. They study lahar deposits and limits of inundation, model flow behavior, develop lahar-hazard maps, and work with community leaders and governmental authorities to help them understand and minimize the risks of devastating lahars.

Fact Sheet↗
USGS2018

Modeled inundation limits of potential lahars from Mount Adams in the White Salmon River Valley, Washington

Lahars large enough to reach populated areas are a hazard at Mount Adams, a massive volcano in the southern Cascade Range of Washington State (fig. 1). It is considered to be still active and has the potential to erupt again. By definition, lahars are gravity-driven flows of water-saturated mixtures of mud and rock (plus or minus ice, wood, and other debris), which originate from volcanoes and have a variety of potential triggering mechanisms (Vallance, 2000; Vallance and Iverson, 2015). Flowing mixtures can range in fluid consistency from something like a milkshake to something more like wet concrete, and they behave like flash floods, in that they can appear suddenly in river channels with little warning and commonly have boulder- or log-choked flow fronts. Lahars are hazardous because they can flow rapidly in confined valleys (commonly 20–35 miles per hour [mph] or 9–16 meters per second [m/s]), can travel more than 100 miles (mi) (161 kilometers [km]) from a source volcano, and can move with incredible destructive force, carrying multi-ton boulders and logs that can act as battering rams (Pierson, 1998). The biggest threats from lahars to downstream communities are present during eruptive activity, and impacts to communities can be dire. For example, a very large eruption-triggered lahar in Colombia in 1985 surprised and killed more than 20,000 people in a large town located about 45 mi (72 km) downstream and out of sight of the volcano that produced it (Pierson and others, 1990). Mount Adams, one of the largest volcanoes in the Cascade Range, is a composite stratocone composed primarily of andesite lava flows. It has been the most continuously active volcano within the 480-mi 2 Mount Adams volcanic field—a region covering parts of Klickitat, Skamania, Yakima, andLewis Counties and part of the Yakama Nation Reservation in Washington State (Hildreth and Fierstein,1995, 1997). About 500,000 years in age, Mount Adams reached its present size by about 15,000 years ago, primarily through the episodic effusion of lava flows; it has not had a history of major explosive eruptions like Mount St. Helens, its neighbor to the west. Timing of the most recent eruptive activity (recorded by four thin tephra layers) is on the order of 1,000 years ago; the tephras are bracketed by 2,500-year-old and 500-year-old ash layers from Mount St. Helens (Hildreth and Fierstein, 1995, 1997). Mount Adams currently shows no signs of renewed unrest. Eruptive history does not tell us everything we need to know about hazards at Mount Adams, however, which are fully addressed in the volcano hazard assessment for Mount Adams (W.E. Scott and others, 1995). This volcano has had a long-active hydrothermal system that circulated acidic hydrothermal fluids, formed by the solution of volcanic gases in heated groundwater, through fractures and permeable zones into upper parts of the volcanic cone. Acid sulfate leaching of rocks in the summit area may still be occurring, but chemical and thermal evidence suggests that the main hydrothermal system is no longer active at Mount Adams (Nathenson and Mariner, 2013). However, these rock-weakening chemical reactions have operated long enough to change about 0.4 cubic miles (mi 3 ) (1.7 cubic kilometers [km 3 ]) of the hard lava rock in the volcano’s upper cone to a much weaker clay-rich rock, thus significantly reducing rock strength and thereby slope stability in parts of the cone (Finn and others, 2007). The two largest previous lahars from Mount Adams were triggered by landslides of hydrothermally altered rock from the upper southwestern flank of the cone, and any future large lahars are likely to be triggered by the same mechanism. Mount Rainier also has had extensive hydrothermal alteration of rock in its upper edifice, and it also has a history of large landslides that transform into lahars (K.M. Scott and others, 1995; Vallance and Scott, 1997; Reid and others, 2001). The spatial depiction of modeled lahar inundation zones accompanying this report, shown in two different map perspectives, is intended to augment (not replace) the existing hazard maps for Mount Adams (W.E. Scott and others, 1995; Vallance, 1999). The maps in this report show potential areas of inundation by lahars of different initial volumes, which are determined by a computer model, LAHARZ (Iverson and others, 1998; Schilling, 1998). One map sheet presents LAHARZ-determined inundation areas on a normal plan-view shaded-relief map of the study area; the other gives an oblique perspective of the landscape with raised topography, as if one were viewing the landscape at an angle from an aircraft (Jenny and Patterson, 2007). LAHARZ was developed after the original hazard maps (based only on mapping of geologic deposits) were made. Predicted inundation zones on these maps provide an alternative approach to estimation of areas that could be inundated as lahars of different volumes pass through the valley. However, there is considerable uncertainty in the exact location of the hazard-zone boundaries shown on these maps, as well as on earlier maps.

Washington↗
USGS2018

Combining InSAR and GPS to determine transient movement and thickness of a seasonally active low-gradient translational landslide

The combined application of continuous Global Positioning System data (high temporal resolution) with spaceborne interferometric synthetic aperture radar data (high spatial resolution) can reveal much more about the complexity of large landslide movement than is possible with geodetic measurements tied to only a few specific measurement sites. This approach is applied to an ~4 km 2 reactivated translational landslide in the Columbia River Gorge (Washington State), which moves mainly during the winter rainy season. Results reveal the complex three-dimensional shape of the landslide mass, how onset of sliding relates to cumulative rainfall, how surface velocity during sliding varies with location on the topographically complex landslide surface, and how the ground surface subsides slightly in weeks prior to downslope sliding.

Geophysical Research Letters↗
USGS2017

United States-Chile binational exchange for volcanic risk reduction, 2015—Activities and benefits

In 2015, representatives from the United States and Chile exchanged visits to discuss and share their expertise and experiences dealing with volcano hazards. Communities in both countries are at risk from various volcano hazards. Risks to lives and property posed by these hazards are a function not only of the type and size of future eruptions but also of distances from volcanoes, structural integrity of volcanic edifices, landscape changes imposed by recent past eruptions, exposure of people and resources to harm, and any mitigative measures taken (or not taken) to reduce risk. Thus, effective risk-reduction efforts require the knowledge and consideration of many factors, and firsthand experience with past volcano crises provides a tremendous advantage for this work. However, most scientists monitoring volcanoes and most officials delegated with the responsibility for emergency response and management in volcanic areas have little or no firsthand experience with eruptions or volcano hazards. The reality is that eruptions are infrequent in most regions, and individual volcanoes may have dormant periods lasting hundreds to thousands of years. Knowledge may be lacking about how to best plan for and manage future volcanic crises, and much can be learned from the sharing of insights and experiences among counterpart specialists who have had direct, recent, or different experiences in dealing with restless volcanoes and threatened populations. The sharing of information and best practices can help all volcano scientists and officials to better prepare for future eruptions or noneruptive volcano hazards, such as large volcanic mudflows (lahars), which could affect their communities.

Circular↗
USGS2016

Landslides in the western Columbia Gorge, Skamania County, Washington

Summary Recent light detection and ranging (lidar) imagery has allowed us to identify and map a large number of previously unrecognized landslides, or slides, in heavily forested terrain in the western Columbia Gorge, Skamania County, Washington, and it has revealed that the few previously recognized areas of instability are actually composites of multiple smaller landslides. The high resolution of the imagery further reveals that landslides in the map area have complex movement histories and span a wide range of relative ages. Movement histories are inferred from relative landslide locations and crosscutting relations of surface features. Estimated age ranges are based on (1) limited absolute dating; (2) relative fineness of landscape surface textures, calibrated by comparison with surfaces of currently active and dated landslides as interpreted from interferometric synthetic aperture radar (InSAR), global positioning system (GPS), and historical records; (3) sharpness and steepness of larger-scale surface morphologic features, calibrated by comparison with similar dated features in other regions; (4) degree of surface erosion; and (5) evidence of erosion or deposition by late Pleistocene (15–22 ka) Missoula floods at or below 200 m altitude. The relative age categories are recent (0 to ~1,000 years old), intermediate-age (~1,000 to ~15,000 years old), and old (>~15,000 years old). Within the 221.5 km 2 map area, we identified 215 discrete landslides, covering 140.9 km 2 (64 percent of the map area). At least 12 of the recent landslides are currently moving or have moved within the last two decades. Mapping for this study expanded the area of previously recognized unstable terrain by 56 percent. Landslide geometries suggest that more than half (62 percent) of these slope failures are translational landslides or composite landslides with translational elements, with failure occurring along gently sloping bedding planes in zones of deeply weathered, locally clay rich volcaniclastic sedimentary units. Approximately two-thirds of the mapped landslide area comprises landslides that have remobilized parts of older slides, and 37 percent of these reactivated slides have involved reactivation of material from two or more older slides. The largest two recent landslides have volumes ≈1 km 3 and runouts ≈6 km. One of these, the Bonneville landslide, temporarily dammed the Columbia River almost 600 years ago, and subsequent dam-break flooding inundated downstream areas. The other, the Red Bluffs landslide, slid into the river adjacent to the Bonneville landslide but apparently did not form a landslide dam. Another such landslide rapidly sliding into the Columbia River today could have a catastrophic impact on downstream communities and on the transportation and energy-distribution infrastructure of the Pacific Northwest.

Washington↗
USGS2016

Extraordinary sediment delivery and rapid geomorphic response following the 2008–2009 eruption of Chaitén Volcano, Chile

The 10 day explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile, draped adjacent watersheds with a few cm to >1 m of tephra. Subsequent lava-dome collapses generated pyroclastic flows that delivered additional sediment. During the waning phase of explosive activity, modest rainfall triggered an extraordinary sediment flush which swiftly aggraded multiple channels by many meters. Ten kilometer from the volcano, Chaitén River channel aggraded 7 m and the river avulsed through a coastal town. That aggradation and delta growth below the abandoned and avulsed channels allow estimates of postdisturbance traction-load transport rate. On the basis of preeruption bathymetry and remotely sensed measurements of delta-surface growth, we derived a time series of delta volume. The initial flush from 11 to 14 May 2008 deposited 0.5–1.5 × 10 6 m 3 of sediment at the mouth of Chaitén River. By 26 May, after channel avulsion, a second delta amassed about 2 × 10 6 m 3 of sediment; by late 2011 it amassed about 11 × 10 6 m 3 . Accumulated sediment consists of low-density vesicular pumice and lithic rhyolite sand. Rates of channel aggradation and delta growth, channel width, and an assumed deposit bulk density of 1100–1500 kg m −3 indicate mean traction-load transport rate just before and shortly after avulsion (∼14–15 May) was very high, possibly as great as several tens of kg s −1 m −1 . From October 2008 to December 2011, mean traction-load transport rate declined from about 7 to 0.4 kg −1 m −1 . Despite extraordinary sediment delivery, disturbed channels recovered rapidly (a few years).

Chaitén Volcano↗
USGS2016

Detecting seasonal landslide movement within the Cascade landslide complex (Washington) using time-series SAR imagery

Detection of slow or limited landslide movement within broad areas of forested terrain has long been problematic, particularly for the Cascade landslide complex (Washington) located along the Columbia River Gorge. Although parts of the landslide complex have been found reactivated in recent years, the timing and magnitude of motion have not been systematically monitored or interpreted. Here we apply novel time-series strategies to study the spatial distribution and temporal behavior of the landslide movement between 2007 and 2011 using InSAR images from two overlapping L-band ALOS PALSAR-1 satellite tracks. Our results show that the reactivated part has moved approximately 700 mm downslope during the 4-year observation period, while other parts of the landslide complex have generally remained stable. However, we also detect about 300 mm of seasonal downslope creep in a terrain block upslope of the Cascade landslide complex—terrain previously thought to be stable. The temporal oscillation of the seasonal movement can be correlated with precipitation, implying that seasonal movement here is hydrology-driven. The seasonal movement also has a frequency similar to GPS-derived regional ground oscillations due to mass loading by stored rainfall and subsequent rebound but with much smaller magnitude, suggesting different hydrological loading effects. From the time-series amplitude information on terrain upslope of the headscarp, we also re-evaluate the incipient motion related to the 2008 Greenleaf Basin rock avalanche, not previously recognized by traditional SAR/InSAR methods. The approach used in this study can be used to identify active landslides in forested terrain, to track the seasonal movement of landslides, and to identify previously unknown landslide hazards.

Washington↗
USGS2014

Reducing risk from lahar hazards: Concepts, case studies, and roles for scientists

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.

Journal of Applied Volcanology↗
USGS2014

Hydrogeomorphic effects of explosive volcanic eruptions on drainage basins

Explosive eruptions can severely disturb landscapes downwind or downstream of volcanoes by damaging vegetation and depositing large volumes of erodible fragmental material. As a result, fluxes of water and sediment in affected drainage basins can increase dramatically. System-disturbing processes associated with explosive eruptions include tephra fall, pyroclastic density currents, debris avalanches, and lahars—processes that have greater impacts on water and sediment discharges than lava-flow emplacement. Geo-morphic responses to such disturbances can extend far downstream, persist for decades, and be hazardous. The severity of disturbances to a drainage basin is a function of the specific volcanic process acting, as well as distance from the volcano and magnitude of the eruption. Postdisturbance unit-area sediment yields are among the world's highest; such yields commonly result in abundant redeposition of sand and gravel in distal river reaches, which causes severe channel aggradation and instability. Response to volcanic disturbance can result in socioeconomic consequences more damaging than the direct impacts of the eruption itself.

Annual Review of Earth and Planetary Sciences↗
USGS2013

Late Holocene history of Chaitén Volcano: new evidence for a 17 th century eruption

Prior to May 2008, it was thought that the last eruption of Chaitén Volcano occurred more than 5,000 years ago, a rather long quiescent period for a volcano in such an active arc segment. However, increasingly more Holocene eruptions are being identified. This article presents both geological and historical evidence for late Holocene eruptive activity in the 17th century (AD 1625-1658), which included an explosive rhyolitic eruption that produced pumice ash fallout east of the volcano and caused channel aggradation in the Chaitén River. The extents of tephra fall and channel aggradation were similar to those of May 2008. Fine ash, pumice and obsidian fragments in the pre-2008 deposits are unequivocally derived from Chaitén Volcano. This finding has important implications for hazards assessment in the area and suggests the eruptive frequency and magnitude should be more thoroughly studied.

Chait�n↗
USGS2013

Pyroclastic density currents associated with the 2008-2009 eruption of Chaitén Volcano (Chile): forest disturbances, deposits, and dynamics

Explosive activity at Chaitén Volcano in May 2008 and subsequent dome collapses over the following nine months triggered multiple, small-volume pyroclastic density currents (PDCs). The explosive activity triggered PDCs to the north and northeast, which felled modest patches of forest as far as 2 km from the caldera rim. Felled trees pointing in the down-current direction dominate the disturbance zones. The PDC on the north flank of Chaitén left a decimeters-thick, bipartite deposit having a basal layer of poorly sorted, fines-depleted pumice-and-lithic coarse ash and lapilli, which transitions abruptly to fines-enriched pumice-and-lithic coarse ash. The deposit contains fragments of mostly uncharred organics near its base; vegetation protruding above the deposit is uncharred. The nature of the forest disturbance and deposit characteristics suggest the PDC was dilute, of relatively low temperature (<200°C), and to first approximation had a dynamic pressure of about 2-4 kPa and velocity of about 30-40 ms -1 . It was formed by directionally focused explosions throughout the volcano's prehistoric, intracaldera lava dome. Dilute, low-temperature PDCs that exited the caldera over a low point on the east-southeast caldera rim deposited meters-thick fill of stratified beds of pumice-and-lithic coarse ash and lapilli. They did not fell large trees more than a few hundred of meters from the caldera rim and were thus less energetic than those on the north and northeast flanks. They likely formed by partial collapses of the margins of vertical eruption columns. In the Chaitén River valley south of the volcano, several-meter-thick deposits of two block-and-ash flow (BAF) PDCs are preserved. Both have a coarse ash matrix that supports blocks and lapilli predominantly of lithic rhyolite dome rock, minor obsidian, and local bedrock. One deposit was emplaced by a BAF that traveled an undetermined distance downvalley between June and November 2008, apparently triggered by partial collapse of a newly effused lava dome on that started growing on 12 May. A second, and larger, BAF related to another collapse of the new lava dome on 19 February 2009 traveled to within 3 km of the village of Chaitén, 10 km downstream of the volcano. It deposited as much as 8-10 m of diamict having sedimentary characteristics very similar to the previous BAF deposit. Charred trees locally encased within the BAD deposits suggest that the flows were of moderate temperature, perhaps as much as 300°C. Erosion of the BAD deposits filling the Chaitén River channel has delivered substantial sediment loads downstream, contributing to channel instability and challenged river management.

Chait�n↗
USGS2013

Acute sedimentation response to rainfall following the explosive phase of the 2008-2009 eruption of Chaitén volcano, Chile

The 10-day explosive phase at the start of the 2008–2009 eruption of Chaitén volcano in southern Chile (42.83°S, 72.65°W) blanketed the steep, rain-forest-cloaked, 77-km 2 Chaitén River drainage basin with 3 to >100 cm of tephra; predominantly fine to extremely fine rhyolitic ash fell during the latter half of the explosive phase. Rain falling on this ash blanket within days of cessation of major explosive activity generated a hyperconcentrated-flow lahar, followed closely by a complex, multi-day, muddy flood (streamflow bordering on dilute hyperconcentrated flow). Sediment mobilized in this lahar-flood event filled the Chaitén River channel with up to 7 m of sediment, buried the town of Chaitén (10 km downstream of the volcano) in up to 3 m of sediment, and caused the lower 3 km of the channel to avulse through the town. Although neither the nature nor rate of the sedimentation response is unprecedented, they are unusual in several ways: (1) Nearly 70 percent of the aggradation (almost 5 m) in the 50–70-m-wide Chaitén River channel was caused by a lahar, triggered by an estimated 20 mm of rainfall over a span of about 24 h. An additional 2 m of aggradation occurred in the next 24–36 h. (2) Direct damage to the town was accomplished by the sediment-laden water-flood phase of the lahar-flood event, not the lahar phase. (3) The volume of sediment eroded from hillslopes and delivered to the Chaitén River channel was at least 3–8 × 10 6 m 3 —roughly 15–40 % of the minimum tephra volume that mantled the Chaitén River drainage basin. (4) The acute sedimentation response to rainfall appears to have been due to the thickness and fineness of the ash blanket (inhibiting infiltration of rain) and the steepness of the basin’s hillslopes. Other possible factors such as the prior formation of an ash crust, development of a hydrophobic surface layer, or large-scale destruction of rain-intercepting vegetation did not play a role.

Chait�n Caldera↗
USGS2013

Volcano crisis response at Yellowstone volcanic complex - after-action report for exercise held at Salt Lake City, Utah, November 15, 2011

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.

Utah↗
USGS2012

Using age of colonizing douglas-fir for the dating of young geomorphic surfaces: a case study

Dating of many types of young (<500 year), dynamic, geomorphic landforms (e.g. mass-movement erosional tracks and deposits, alluvial terraces, flood plains, etc.) for purposes of hazard assessment and mitigation commonly requires greater dating precision than is available through radiocarbon dating or other methods. Ages of trees growing on landform surfaces have been used in a number of studies to estimate the time of landform creation or surface clearing, but the time lag between surface formation or disturbance and the reestablishment of trees can vary from 1 to more than 200 years (Desloges and Ryder 1990; Frenzen et al. 1988, 2005; Larsen and Bliss 1998; McCarthy and Luckman 1993; Sigafoos and Hendricks 1969; Winter et al. 2002). Appropriate lag times for selected tree species and for particular climatic and altitudinal ranges must be determined for the method to be useful.

Book chapter↗