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.
553. Nuth and Kaab (2011) Co-registration and bias corrections of satellite elevation data sets for quantifying glacier thickness change
     There are an increasing number of digital elevation models (DEMs) available worldwide for deriving elevation differences over time, including vertical changes on glaciers. Most of these DEMs are heavily post-processed or merged, so that physical error modelling becomes difficult and statistical error modelling is required instead. We propose a three-step methodological framework for assessing and correcting DEMs to quantify glacier elevation changes: (i) remove DEM shifts, (ii) check for elevation-dependent biases, and (iii) check for higher-order, sensor-specific biases. A simple, analytic and robust method to co-register elevation data is presented in regions where stable terrain is either plentiful (case study New Zealand) or limited (case study Svalbard). The method is demonstrated using the three global elevation data sets available to date, SRTM, ICESat and the ASTER GDEM, and with automatically generated DEMs from satellite stereo instruments of ASTER and SPOT5-HRS. After 3-D co-registration, significant biases related to elevation were found in some of the stereoscopic DEMs. Biases related to the satellite acquisition geometry (along/cross track) were detected at two frequencies in the automatically generated ASTER DEMs. The higher frequency bias seems to be related to satellite jitter, most apparent in the back-looking pass of the satellite. The origins of the more significant lower frequency bias is uncertain. ICESat-derived elevations are found to be the most consistent globally available elevation data set available so far. Before performing regional-scale glacier elevation change studies or mosaicking DEMs from multiple individual tiles (e.g. ASTER GDEM), we recommend to co-register all elevation data to ICESat as a global vertical reference system.
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.

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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