39. Riedel (1997) Geologic hazard and floodplain management: Mount Rainier General Management Plan
    Mount Rainier National Park (MORA) is in the process of developing a 20-year General Management Plan (GMP) in time for its 100th anniversary celebration in 1999. This report was prepared to assist planners in managing geologic hazards and floodplains in front country development and visitor use sites. NPS management policy in regard to geologic hazards focuses on saving human life, and avoiding hazard if possible. Further, where facilities must be located in hazard areas, design and siting should include mitigating measures to minimize risk to life and human property. At MORA, however, most developed areas are in mapped volcanic hazard zones. The designation of Mount Rainier as a Decade Volcano Study Area by the National Research Council in 1994 underscores the seriousness of the volcanic hazards at Mount Rainier. Due to NPS management policy and the considerable hazards at Mount Rainier, a geologic hazard mitigation approach is presented that avoids unrealistic closer of large areas of the park. On a short time scale of 0-5 years, this approach emphasizes education and contingency planning for response to hazards as means of mitigating volcanic hazards at the park. GMP hazard mitigation is focused on longer time scales. The recommended approach is that no new housing, administrative facilities, concessions or overnight visitor facilities be constructed in high hazard zones. A risk analysis of 23 visitor and administrative sites was conducted to identify the most hazardous and risky sites in the park. This analysis considered hazard, value and vulnerability at each of these sites. Components of hazard in the risk formula included both deterministic and probabilistic factors, while emphasizing the hazard presented by debris flows. Results indicate that White River Campground, Longmire and Cougar Rock Campground are the three sites at highest risk in the park by a large margin. It is recommended that hazard mitigation in the GMP focus on these three areas. White River Campground is by far the most hazardous and risky site at MORA with a hazard score two times greater than that of the next most hazardous site, Camp Schurman. High hazard score at White River Campground is due to the site's proximity to the volcano, location below fractured, hydrothermally weakened rocks on Little Tahoma Peak, and position next to the floodplain of White River. Nonvolcanic geologic hazards are also a concern at MORA. Hazards such as rock falls, snow avalanches and landslides occur at sites scattered throughout the park. The risk analysis and field studies also showed that the portion of Tahoma Woods north of highway 706 is an appropriate place for future developments. Trenches dug in spring 1995 indicate that this site has not been inundated by a debris flow in the past 10,000 years. Further, Tahoma Woods is outside case II and case III debris flow inundation zones, which have the most frequent recurrence intervals. Floodplain management at MORA floows the NPS Floodplain Management Guideline (1993). Ten of 23 developed sites, which are primarily day use areas and entrances, are actions that are excepted from compliance with the guideline. Preliminary floodplain assessments at 13 other sites indicate that only three sites are within regulatory floodplains. Detailed floodplain studies were conducted at Longmire, Carbon Entrance and Ipsut Campground to provide information that will allow these sites to be in compliance with the guideline. Walk-in sites at Ipsut and Loop-C of Ohanapecosh campgrounds are recommended for temporary seasonal closure during periods of high river flow in spring and early winter. Floodplains at MORA are as dynamic as at any NPS area, due to the movement of vast amounts of water and glacial sediment carried by the large rivers down the steep slopes of the volcano. It is estimated that because of rapid rates of deposition and erosion, typical floodplain mapping techniques would be inaccurate in as little as 10 years after completion. Therefore, it is recommended that floodplain boundaries be drawn conservatively, without the use of expensive hydraulic modeling techniques. Further, stream gaging stations place on the large rivers of the park would provide important information to managers on rates of stream channel deposition and channel instability.
552. Hotaling et al. (2022) Summer dynamics of microbial diversity on a mountain glacier
     Glaciers are rapidly receding under climate change. A melting cryosphere will dramatically alter global sea levels, carbon cycling, and water resource availability. Glaciers host rich biotic communities that are dominated by microbial diversity, and this biodiversity can impact surface albedo, thereby driving a feedback loop between biodiversity and cryosphere melt. However, the microbial diversity of glacier ecosystems remains largely unknown outside of major ice sheets, particularly from a temporal perspective. Here, we characterized temporal dynamics of bacteria, eukaryotes, and algae on the Paradise Glacier, Mount Rainier, USA, over nine time points spanning the summer melt season. During our study, the glacier surface steadily darkened as seasonal snow melted and darkening agents accumulated until new snow fell in late September. From a community-wide perspective, the bacterial community remained generally constant while eukaryotes and algae exhibited temporal progression and community turnover. Patterns of individual taxonomic groups, however, were highly stochastic. We found little support for our a priori prediction that autotroph abundance would peak before heterotrophs. Notably, two different trends in snow algae emerged—an abundant early- and late-season operational taxonomic unit (OTU) with a different midsummer OTU that peaked in August. Overall, our results highlight the need for temporal sampling to clarify microbial diversity on glaciers and that caution should be exercised when interpreting results from single or few time points.
551. Kincaid (2024) Using historic glacial data and GIS to predict Mount Rainier National Park's glacial future
     Will Washington state have glaciers 100 years from now (year 2124)? Due to generally warmer weather glaciers are largely in retreat globally, including the glaciers in Washington state. In Washington state summer glacial meltwater plays a vital role in the survival of wildlife and is needed for human purposes that include recreation, power generation, drinking, agricultural, and industrial. This project looked at the most resilient glaciers in Washington state, the glaciers at Mount Rainier National Park. Historic measurements were used in an exponential growth calculation to project the amount in acres each glacier at Mount Rainer will advance or retreat over the next 100 years. The glaciers were digitized into ArcGIS Pro and then adjusted according to the calculations. The results of the project show that all the glaciers at Mount Rainier should be intact in 2124. This is of vital importance to wildlife and human populations that depend on the summer meltwater for various purposes.
550. Florea et al. (2022) Fumarole-ice dynamics in cryo-speleology on volcanic edifices—Mount Rainier, Washington, USA
     The persistent fumarole ice caves nearly circumnavigating the East Crater of Mount Rainier in the Cascade Volcanic Arc in Washington, USA, are a natural laboratory to study the dynamic equilibrium between thermal flux and glacial ice. The large circum‐crater passage connects to entrances on the crater rim by steep transverse passages, and fumarole gas convection and advection maintains the cave passage distribution and morphology. Between August 2016 and August 2017, we collected hourly data using remote sondes that include temperatures at three fumarole, cave air temperature and pressure, water temperature and depth in an in‐cave meltwater lake, and the outside temperature and snow depth at Paradise Visitors Center. Correlation and wavelet analyses of these data reveal complex associations between patterns of weather, fumarole activity, and lake level. At longer scales, fumarole temperatures behave largely independently and connected to spatial and temporal changes in volcanic heat flux and glacial melt circulation. At the scale of individual storm‐events, major snowfalls seal the cave entrances, increasing cave air temperature and pressure from fumarole output and causing rising lake levels from increased melt until entrances reopen. Repeating freeze‐thaw cycles observed in the cave monitoring data are a primary cause of crater mass‐wasting.
549. Stenner et al. (2023) Morphodynamics of glaciovolcanic caves—Mount Rainier, Washington, USA
     The twin summit craters of Mount Rainier, Washington, USA host the largest known glaciovolcanic caves in the world and at 4382 m, the highest elevation caves in the USA. The caves are formed in ice at the glacier-rock interface by volcanogenic gases and atmospheric advection. However, the way in which discrete caves are formed and evolve remains poorly understood. Surveys of the cave systems in 1970−1973 and 1997−1998 in both the West and East Craters documented cave passage morphology. Field expeditions from 2014−2017 comprehensively surveyed the Rainier summit caves and undertook thermal imaging and temperature monitoring. Significant changes had occurred. In the East Crater, documented cave length has nearly doubled since 1973 to 3593 m of passage spanning 144 m of depth, revealing a new subglacial lake, and now nearly circumnavigating the East Crater. Of the reported increase in length, some 600 m of the mapped passage is possibly newly formed. Across 47 years of observation, certain sections of the cave appear to be preserved in form and position through time, while others are more actively being lost or forming. Conserved passages are generally sub-horizontal, passages following the curvilinear crater contours, show low temperature variability, and are dependent on perennial fumarolic activity or distributed heat flux emanating from warm bedrock and sediment floors. Transient passages are smaller diameter dendritic passages following the slope of the ice-rock interface towards entrance zones and normal to the circum-crater passage. They also show higher variability in temperature and airflow and are subject to seasonal weather and mechanical collapse, which may contribute to transience. Additional research is required to confirm the mechanisms maintaining conserved passages and formation of transient passages.
548. Vaux et al. (2026) Dissolved black carbon in North Cascades snow, meltwater, and a downstream river
     Quantification of black carbon on snow in the Cascade Range is needed due to increasing wildfire intensity and frequency. Here, the benzenepolycarboxylic acid (BPCA) molecular method was used to measure dissolved black carbon (DBC) in snow, nearby rivers, streams, and supraglacial melt collected in 2022 and 2023 from Mount Baker and Mount Rainier. The average DBC concentration in snow was 9 ± 4 μg-C/L and 10 ± 6 μg-C/L in stream, river, and supraglacial meltwater samples. The DBC method provides black carbon source identification via BPCA characterization. DBC concentrations and BPCA proportions were compared to modeled smoke deposition from the Navy Aerosol Analysis and Prediction System reanalysis model. In both years, total deposition from May through October was approximately 670 mg/m2. However, early season smoke deposition (May through July) was four times higher in 2023 than 2022, indicating seasonal variability in the timing of deposition. Dry deposition accounted for over 80 percent of total late season smoke deposition (August through October) in both 2022 and 2023, while wet deposition accounted for 75 and 30 percent of total early season deposition in 2022 and 2023, respectively. The largest smoke deposition events on Mount Baker coincided with precipitation events and enrichment of benzenepentacarboxylic acid, a marker of biomass burning, in snow. Using the Snow, Ice, and Aerosol Radiative model, we estimated an average albedo of 0.68 ± 0.03. The resulting instantaneous radiative forcing attributable to the presence of BC in snow ranged from 3 to 16 W/m2, with an average of 7.47 ± 3.3 W/m2.

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The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.

Website Resources

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington 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

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

General inquiries: vhpweb@usgs.gov