175. Prejean et al. (2004) Remotely triggered seismicity on the United States west coast following the M_w 7.9 Denali fault earthquake
     The M_w 7.9 Denali fault earthquake in central Alaska of 3 November 2002 triggered earthquakes across western North America at epicentral distances of up to at least 3660 km. We describe the spatial and temporal development of triggered activity in California and the Pacific Northwest, focusing on Mount Rainier, the Geysers geothermal field, the Long Valley caldera, and the Coso geothermal field. The onset of triggered seismicity at each of these areas began during the Love and Raleigh waves of the M_w 7.9 wave train, which had dominant periods of 15 to 40 sec, indicating that earthquakes were triggered locally by dynamic stress changes due to low-frequency surface wave arrivals. Swarms during the wave train continued for ~4 min (Mount Rainier) to ~40 min (the Geysers) after the surface wave arrivals and were characterized by spasmodic bursts of small (M ≤ 2.5) earthquakes. Dynamic stresses within the surface wave train at the time of the first triggered earthquakes ranged from 0.01 MPa (Coso) to 0.09 MPa (Mount Rainier). In addition to the swarms that began during the surface wave arrivals, Long Valley caldera and Mount Rainier experienced unusually large seismic swarms hours to days after the Denali fault earthquake. These swarms seem to represent a delayed response to the Denali fault earthquake. The occurrence of spatially and temporally distinct swarms of triggered seismicity at the same site suggests that earthquakes may be triggered by more than one physical process.
465. Pelto (2018) How unusual was 2015 in the 1984-2015 period of the North Cascade Glacier annual mass balanace?
     In 1983, the North Cascade Glacier Climate Project (NCGCP) began the annual monitoring of the mass balance on 10 glaciers throughout the range, in order to identify their response to climate change. Annual mass balance (Ba) measurements have continued on seven original glaciers, with an additional two glaciers being added in 1990. The measurements were discontinued on two glaciers that had disappeared and one was that had separated into several sections. This comparatively long record from nine glaciers in one region, using the same methods, offers some useful comparative data in order to place the impact of the regional climate warmth of 2015 in perspective. The mean annual balance of the NCGCP glaciers is reported to the World Glacier Monitoring Service (WGMS), with two glaciers, Columbia and Rainbow Glacier, being reference glaciers. The mean Ba of the NCGCP glaciers from 1984 to 2015, was -0.54 m w.e.a^-1 (water equivalent per year), ranging from -0.44 to -0.67 m w.e.a^-1 for individual glaciers. In 2015, the mean Ba of nine North Cascade glaciers was -3.10 m w.e., the most negative result in the 32-year record. The correlation coefficient of Ba was above 0.80 between all North Cascade glaciers, indicating that the response was regional and not controlled by local factors. The probability of achieving the observed 2015 Ba of -3.10 is 0.34%.
464. Radic et al. (2008) Analysis of scaling methods in deriving future volume evolutions of valley glaciers
     Volume–area scaling is a common tool for deriving future volume evolutions of valley glaciers and their contribution to sea-level rise. We analyze the performance of scaling relationships for deriving volume projections in comparison to projections from a one-dimensional ice-flow model. The model is calibrated for six glaciers (Nigardsbreen, Rhonegletscher, South Cascade Glacier, Sofiyskiy glacier, midre Lovénbreen and Abramov glacier). Volume evolutions forced by different hypothetical mass-balance perturbations are compared with those obtained from volume–area (V-A), volume–length (V-L) and volume–area–length (V-A-L) scaling. Results show that the scaling methods mostly underestimate the volume losses predicted by the ice-flow model, up to 47% for V-A scaling and up to 18% for V-L scaling by the end of the 100 year simulation period. In general, V-L scaling produces closer simulations of volume evolutions derived from the ice-flow model, suggesting that V-L scaling may be a better approach for deriving volume projections than V-A scaling. Sensitivity experiments show that the initial volumes and volume evolutions are highly sensitive to the choice of the scaling constants, yielding both over- and underestimates. However, when normalized by initial volume, volume evolutions are relatively insensitive to the choice of scaling constants, especially in the V-L scaling. The 100 year volume projections differ within 10% of initial volume when the V-A scaling exponent commonly assumed, γ = 1.375, is varied by −30% to +45% (γ = [0.95, 2.00]) and the V-L scaling exponent, q = 2.2, is varied by −30% to +45% (q = [1.52, 3.20]). This is encouraging for the use of scaling methods in glacier volume projections, particularly since scaling exponents may vary between glaciers and the scaling constants are generally unknown.
463. Vallance and Sisson (2022) Geologic field-trip guide to volcanism and its interaction with snow and ice at Mount Rainier, Washington
     Mount Rainier is the Pacific Northwest's iconic volcano. At 4,393 meters and situated in the south-central Cascade Range of Washington State, it towers over cities of the Puget Lowland. As the highest summit in the Cascade Range, Mount Rainier hosts 26 glaciers and numerous permanent snow fields covering 87 square kilometers and having a snow and ice volume of about 3.8 cubic kilometers. It remains by far the most heavily glacier-clad mountain in the conterminous United States despite having lost about 14 percent of its ice volume between 1970 and 2008. Five major rivers head at Mount Rainier—the White, Carbon, Puyallup, Nisqually, and Cowlitz Rivers. Because Mount Rainier is situated west of the Cascade Range crest, all of these rivers eventually turn and drain westward. The Puget Lowland, situated west to northwest of Mount Rainier, is the Pacific Northwest's most densely populated area, including Seattle, Tacoma, and Olympia. The Puget Lowland is now home to a population of more than 4.5 million and a vibrant economy. Mount Rainier is one of the most hazardous volcanoes in the United States, not so much because of its explosivity, but rather because of its frequent eruptions, its propensity to produce voluminous far-traveled lahars, and its proximity to large population centers of the Puget Lowland. Steep-sided, glacially carved valleys serve as lahar conduits, and even mild eruptions commonly produced large lahars that traveled into areas now populated by hundreds of thousands of people. This guide describes a five-day field trip to view the geology of Mount Rainier as it relates to volcanism and its interaction with snow and ice. Day 1 will focus on lahars in the White River valley. We will drive to Enumclaw, Washington, to begin the day then work our way back upvalley toward Mount Rainier. Day 2 concentrates on geology of the Sunrise-Glacier Basin area within Mount Rainier National Park. As part of day 2 activities, we will hike about 10 miles from Sunrise to the top of Burroughs Mountain, down into Glacier Basin, and be picked up at White River Campground. On day 3 we will pack up and move to Paradise, stopping to examine geology along Stevens Canyon Road. We will hike from Paradise along the Golden Gate Trail and eventually eastward to the former Paradise Ice Caves area (the ice caves have melted out). Day 4 involves hiking from Comet Falls trailhead to Mildred Point and return (~7 miles; 11 km), examining geology along the way. During the first half of day 5, we will visit sites on the south side of Mount Rainier to study lahar deposits, then return to the tour origin.
462. Cutter et al. (2019) The Nisqually River: Risk assessment and recommendations for future actions
     This report is intended to assess the Nisqually River, identifying problem areas threatening park infrastructure, recommending further work, and note deficiencies and improvements to be made for the next actions taken on the project.
461. Kellermann (2022) Developing and testing a geomorphic mapping protocol in Mount Rainier National Park, Washington
     The grand landscapes and river systems of Mount Rainier National Park (MORA) are influenced by its glaciovolcanic geology and the temperate climate of the Pacific Northwest. Mapping geomorphic changes is a crucial step to understanding, interacting with, and preserving the pristine environments of the Park. Geologic hazards and large-scale hydrologic events are common within park boundaries, putting infrastructure and cultural and historical sites at risk of permanent damage. In this study, I present a protocol for mapping geomorphic features remotely and in the field, and I test the protocol along an at-risk road segment along the Nisqually River. With ArcGIS Pro, I defined site boundaries with a watershed delineation, designated key geomorphic features custom to the unique environment of the Park, and assigned key attribute domains to further describe each mapped feature. Then, I mapped landform features using LiDAR and aerial imagery in Pro and used ArcGIS Online and Field Maps for in-field mapping with a mobile tablet and a backpack-mounted GNSS receiver. After extensive testing, the protocol is in its preliminary phase and ready to be applied to other park field sites for further testing and repeat mapping projects. The resulting inventory suggests that the protocol is suitable for the remote and rugged characteristics of the Park when paired with recent LiDAR data and favorable GNSS conditions. The standardized methods and taxonomy proposed in the protocol allow for recording landform changes and initial site characterization that can be used to identify locations for hazard mitigation. The protocol is repeatable, providing a standardized format useful for comparison between different locations and timescales. While the protocol is designed for the features found near Mount Rainier, it can be readily modified for other fluvial and hillslope environments. In its final form, this geomorphic mapping protocol will equip MORA geologists and resource managers with a standard approach to documenting MORA's most geologically dynamic and at-risk infrastructure and resources.

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