101. Mills (1979) Some implications of sediment studies for glacial erosion on Mount Rainier, Washington
     A study of glacial sediments throws light on rates and mechanisms of glacial erosion on Mount Rainier, Washington. Suspended-sediment transport measurements suggest that most of the Nisqually River's suspended-sediment load has been entrained by the time the stream emerges from beneath the terminus of Nisqually Glacier. Calculations of the englacial- and superglacial-debris loads of the Nisqually Glacier indicate that more than two-thirds of the stream sediment must be derived subglacially. Lithologic composition of outwash and theoretical considerations also suggest that valley glaciers on Mount Rainier have exceptionally high subglacial erosion rates.
450. Fordham (2022) Glacier Peak and the chocolate factory: Recurring debris flows from the eastern flank of Glacier Peak stratovolocano, North Cascades, Washington State, USA
     Alpine mass wasting events can have wide ranging impacts that extend past their headwater origins reaching down to lowland population centers. The Suiattle River, which drains the eastern flank of Glacier Peak in the North Cascades of Washington State, is a dominant contributor of suspended sediment in the region. Normalized for drainage area, the Suiattle River supplies more suspended sediment than nearly any other river in the region and more than twice as much as the White Chuck River, which drains the western flank of the volcano. Despite its known importance to the regional sediment budget, the specific geomorphic drivers of the anomalous sediment load on the Suiattle have received relatively little attention in the literature. In this study, I build on previous work to explore the magnitude, timing, triggering mechanisms, and the spatial distribution of sediment loading events in the Suiattle River Basin. My historical analysis shows that major debris flow activity initiated in the late-1930s, with a total of nine historic debris flows since then (RI = 9.3 years). One previously unreported circa late-1940s debris flow was identified from reanalysis of dendrochronology (Slaughter, 2004) and historical aerial imagery. From topographic differencing, I placed a minimum bound of ~4.9 M m3 (±0.6 M m3) on the material incised from the most recent valley filling debris flow deposits. Historical accounts suggest that major debris flows happen at the hottest times of the year in the absence of precipitation, with two eyewitness accounts of debris flows triggered by glacial outburst floods. Historical photos, remote sensing, and field measurements of terrace heights suggest that incision into historic debris flow deposits occurs soon after deposition and tapers after the first few years. To examine smaller more recent debris flows, I created a framework to automatically extract debris flow timing, duration, and magnitude from USGS turbidity and discharge data over the period 2011 to 2020. I identified 28 individual debris flow events that occurred in every year in the record. To evaluate triggering mechanisms, I calculated prior day maximum temperature anomalies for all non-debris flow days and for days when a debris flow started. Debris flow start days were shown to be statistically warmer than non-debris flow days (mean of -0.21 °C and 2.48 °C, respectively; ks test, dm = 0.314, p = 0.007). This suggests that minor debris flows are triggered by high temperatures and, like the historical major debris flows, points to glacier outburst floods as the primary initiation process. I estimate suspended sediment loads attributable to minor debris flows, anomalous sediment flushing events following debris flows, and suspended sediment loads outside of these categories. Together debris flows and flushing account for ~21% of the mean annual load on the Suiattle. At Glacier Peak, Chocolate Glacier is unique. Its high propensity for glacier outburst floods makes it the dominant source of debris flows and suspended sediment, vastly outweighing contributions from other glaciers on the mountain. The frequency and magnitude of debris flows from Chocolate Glacier bare similarities to South Tahoma Glacier at Mount Rainier. Combined, my findings show that debris flows deliver large quantities of sediment to the mainstem river at both annual and decadal timescales. This work is a step toward understanding how sediment supplied from alpine mass wasting events shapes downstream geomorphic processes. My findings have implications for how ongoing climate change may alter cascading hazards in these systems.
449. Almekinder (2022) Using spectral indices to determine the effects of the summer 2021 North American heat wave at Mount Rainier, Washington
     Quality of life at Mount Rainier and the surrounding region is dependent on annual snowpack and subsequent snowmelt. Winter storm observations, snowpack, and the rate of snowmelt all play critical roles in determining the health of the environment. To help analyze these factors, users and consumers rely on remotely sensed data to analyze the past, present, and future of the area. The Normalized Difference Snow Index (NDSI) and Normalized Difference Vegetation Index (NDVI), collected from satellite imagery, are two spectral indices used with analyzing snowpack and vegetation health to assist risk mitigation for wildfires, glacial change, and river ecosystems. This project used NDSI and NDVI to determine if the 2021 North American heat wave had any significant effects on vegetation health, snowpack, and glacial size over a five-year study period. Landsat 8 satellite imagery was acquired, corrected for any atmospheric bias, and processed through GIS techniques. Despite yearly fluctuation of warmer and cooler years, results show a progressive increase in snowmelt with 2021 showing the highest percentage during the study period and the highest differential from the mean of all years in the study. Vegetation labeled as "Healthy" saw the biggest decrease between consecutive years from 2020-2021. Also in 2021, Mount Rainier saw its glaciers recede to their lowest total area since 2005. Conclusions show that general warming trends are occurring in the Pacific Northwest and the heat wave exacerbated total glacial area, total snow area, and vegetation health. This Masters project contributes to future extreme weather anomalies and related results.
448. George et al. (2022) Modeling the dynamics of lahars that originate as landslides on the west side of Mount Rainier, Washington
     Large lahars pose substantial threats to people and property downstream from Mount Rainier volcano in Washington State. Geologic evidence indicates that these threats exist even during the absence of volcanic activity and that the threats are highest in the densely populated Puyallup and Nisqually River valleys on the west side of the volcano. However, the precise character of these threats can be difficult to anticipate. To help predict depths and rates of possible lahar inundation in the area, this report presents the results of simulations of hypothetical future lahars that originate high on the west side of Mount Rainier and travel downstream into the Puyallup and Nisqually River valleys. Many of the results portrayed as still images in the figures of this report are also available as animated files that can be accessed at the web address provided in the figure captions. We simulated eight scenarios, including worst-case scenarios in which the simulated lahars are similar in size and mobility to the approximately 260 million cubic meter (Mm³; 340 million cubic yard) Electron Mudflow lahar that descended from Mount Rainier and inundated the Puyallup River valley about 500 years ago. The other six scenarios place the worst-case scenarios in perspective by simulating lahars that originate from the same source areas but have smaller volumes or lesser mobilities. We perform our simulations using an open-source software package that we developed called D-Claw. The numerical model composing the kernel of D-Claw solves a system of five hyperbolic partial differential equations that describe the depth-averaged dynamics of static or flowing grain-fluid mixtures interacting with three-dimensional topography. In D-Claw, the volume fraction occupied by solid grains is a dependent variable that can freely evolve, enabling simulation of landslide liquefaction and of lahar interaction with static bodies of water. The latter feature facilitates a seamless simulation of a lahar in the Nisqually River valley entering Alder Lake reservoir. In the event of an approximately 260 Mm³ high-mobility lahar originating on the west side of Mount Rainier, our results point to two areas of pronounced hazard. One area, comprising the densely populated lowlands of Orting, Washington, and environs, could be inundated by lahars originating from either the Sunset Amphitheater or Tahoma Glacier headwall areas. In the worst-case scenario we consider for the Orting lowlands, which involves a 260 Mm³ high-mobility lahar originating from a landslide in the Sunset Amphitheater, a flow front approximately 4 meters deep and traveling about 4 meters per second reaches the Orting lowlands about 1 hour after the onset of slope failure. After passing through the Orting lowlands, the simulated lahar slows down and comes to rest in the valleys surrounding Sumner and Puyallup. A second area of pronounced hazard is the stretch of the Nisqually River valley beginning in Mount Rainier National Park and extending downstream to Alder Lake reservoir and Alder Dam. This area would be substantially affected in the worst-case scenario that involves a 260 Mm³ high-mobility lahar originating from the Tahoma Glacier headwall area—the locality identified by a previous study as the sector of Mount Rainier most prone to large-scale gravitational collapse. The simulated lahar passes through the area of Ashford, Washington, within about 20 minutes of the onset of slope failure and reaches the head of Alder Lake within about 50 minutes. The lahar ultimately displaces enough reservoir water to cause overtopping of the 100 meter (330 foot) tall Alder Dam, but consequences of such dam overtopping are not addressed in this report.
447. Fountain et al. (2022) Glaciers of the Olympic Mountains, Washington: The past and future 100 years
     In 2015, the Olympic Mountains contained 255 glaciers and perennial snowfields totaling 25.34 ± 0.27 km², half of the area in 1900, and about 0.75 ± 0.19 km³ of ice. Since 1980, glaciers shrank at a rate of −0.59 km² yr^-1 during which time 35 glaciers and 16 perennial snowfields disappeared. Area changes of Blue Glacier, the largest glacier in the study region, was a good proxy for glacier change of the entire region. Modeled glacier mass balance, based on monthly air temperature and precipitation, correlates with glacier area change. The mass balance is highly sensitive to changes in air temperature rather than precipitation, typical of maritime glaciers. In addition to increasing summer melt, warmer winter temperatures changed the phase of precipitation from snow to rain, reducing snow accumulation. Changes in glacier mass balance are highly correlated with the Pacific North American index, a proxy for atmospheric circulation patterns and controls air temperatures along the Pacific Coast of North America. Regime shifts of sea surface temperatures in the North Pacific, reflected in the Pacific Decadal Oscillation (PDO), trigger shifts in the trend of glacier mass balance. Negative ("cool") phases of the PDO are associated with glacier stability or slight mass gain whereas positive ("warm") phases are associated with mass loss and glacier retreat. Over the past century the overall retreat is due to warming air temperatures, +0.7°C in winter and +0.3°C in summer. The glaciers in the Olympic Mountains are expected to largely disappear by 2070.
446. Swift et al. (2021) The hydrology of glacier-bed overdeepenings: Sediment transport mechanics, drainage system morphology, and geomorphological implications
     Evacuation of basal sediment by subglacial drainage is an important mediator of rates of glacial erosion and glacier flow. Glacial erosion patterns can produce closed basins (i.e., overdeepenings) in glacier beds, thereby introducing adverse bed gradients that are hypothesized to reduce drainage system efficiency and thus favour basal sediment accumulation. To establish how the presence of a terminal overdeepening might mediate seasonal drainage system evolution and glacial sediment export, we measured suspended sediment transport from Findelengletscher, Switzerland during late August and early September 2016. Analyses of these data demonstrate poor hydraulic efficiency of drainage pathways in the terminus region but high sediment availability. Specifically, the rate of increase of sediment concentration with discharge was found to be significantly lower than that anticipated if channelized flow paths were present. Sediment availability to these flow paths was also higher than would be anticipated for discrete bedrock-floored subglacial channels. Our findings indicate that subglacial drainage in the terminal region of Findelengletscher is dominated by distributed flow where entrainment capacity increases only marginally with discharge, but flow has extensive access to an abundant sediment store. This high availability maintains sediment connectivity between the glacial and proglacial realm and means daily sediment yield is unusually high relative to yields exhibited by similar Alpine glaciers. We present a conceptual model illustrating the potential influence of ice-bed morphology on subglacial drainage evolution and sediment evacuation mechanics, patterns and yields, and recommend that bed morphology should be an explicit consideration when monitoring and evaluating glaciated basin sediment export rates.

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CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, May 27, 2022, 8:23 AM PDT (Friday, May 27, 2022, 15:23 UTC)

CASCADE RANGE VOLCANOES
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal background levels of activity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake in Oregon.

Recent Observations: In the past week, small earthquakes were detected at Mount Rainier (M0.2 to M1.2), Mount St. Helens (M0.4), Mount Hood (M-0.7 to M0.7), and Newberry Volcano (M-0.5 to M1.2). These earthquakes are consistent with normal background activity. Also this week, field crews installed two new lahar detection sites along the Puyallup River valley at Mount Rainier.

The U.S. Geological Survey and Pacific Northwest Seismic Network (PNSN) continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.

Website Resources
For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo" target="_blank" title="https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: https://pnsn.org/volcanoes" target="_blank" title="https://pnsn.org/volcanoes">https://pnsn.org/volcanoes">https://pnsn.org/volcanoes">https://pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/natural-hazards/volcano-hazards/notifications" target="_blank" title="https://www.usgs.gov/natural-hazards/volcano-hazards/notifications">https://www.usgs.gov/natural-hazards/volcano-hazards/notifications">https://www.usgs.gov/natural-hazards/volcano-hazards/notifications">https://www.usgs.gov/natural-hazards/volcano-hazards/notifications

The U.S. Geological Survey and Pacific Northwest Seismic Network (PNSN) continue to monitor these volcanoes
closely and will issue additional updates and changes in alert level as warranted.

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo" target="_blank" title="https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo">https://www.usgs.gov/observatories/cvo

For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes" target="_blank" title="http://www.pnsn.org/volcanoes">http://www.pnsn.org/volcanoes">http://www.pnsn.org/volcanoes">http://www.pnsn.org/volcanoes

For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information" target="_blank" title="https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information">https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information">https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information">https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information

CONTACT INFORMATION:

Jon Major, Scientist-in-Charge, Cascades Volcano Observatory, jjmajor@usgs.gov

General inquiries: vhpweb@usgs.gov
Media: Ryan McClymont, PIO, USGS Office of Communications and Publishing rmcclymont@usgs.gov