136. Pringle et al. (2000) Mount Rainier: Northwest Geological Society field trip 2000
     This trip circumnavigates Mount Rainier via the Duwamish, Puyallup, Nisqually, Cowlitz, and White River drainages. Along the way we examine a wide variety of geologic features, deposits, and geologic hazards. Because of its hazards and increasing population pressures in the region, Mount Rainier was designated a Decade Volcano by the International Association of Volcanology and Chemistry of the Earth's Interior in 1992. Within two years of the Decade Volcano workshop, the National Research Foundation published its report outlining a strategy for study of Mount Rainier. In keeping with this designation, researchers have made considerable progress since then in examining the history, behavior, structure, and hazards of the volcano with a main goal of mitigating risk. At the same time, a group called the Mount Rainier Volcanic Hazards Work Group (MORAWOG), composed of Federal, state, and local officials and members of the public, has met quarterly to educate themselves and others about the volcano and to prepare for future volcanic unrest. Within the past year the group completed a working draft of a Mount Rainier Response Plan. This field trip provides an overview of what we presently know about Mount Rainier's geologic and glacial history. During the trip, we also will hear about recent research at the volcano and will inspect the geologic evidence for debris flows, the most important class of geologic hazards at Mount Rainier. This text is a compilation of the work of numerous researchers, many of whom are continuing their work at Mount Rainier. We also have relied heavily on the work of Crandell, Mullineaux,Fiske, Hopson, Waters, and others whose earlier efforts have provided an important foundation for further studies. All units are metric except road-log mileage. A note about National Park Service (NFS) etiquette: please do not do any digging within the boundaries of Mount Rainier National Park. Permits, which can be obtained from the Park Superintendent, are required for sample collecting.
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