# Volcanoes/Mount Rainier

Mount Rainier is a volcanic peak in southwestern Washington state of the United States of America. It rises to a height of 4,395 m as the highest peak in the Cascade Range.

## Geoseismology

"Local activity has been increasing each month for the last three months. We have been averaging about 1-3 'Mt. Ranier Events' per 5-day period with an increase to about five per 5-day period last September 1968. This April, the events increased to approximately five per 5-day period. In May, it increased to about six per 5-day period and as of 15 June the increase is to approximately 12 per 5-day period."
"Though Mount Rainier looks serene and quiet viewed on a nice day the Visitors Center, it is actually a very active and noisy place. Regular tectonic earthquakes occur several times a month, but glacier quakes, avalanches, wind, landslides, icefalls and rowdy mountaineers also shake the ground and are picked up by our seismometers. There is an astounding amount of seismic activity on the seismic stations high on the mountain any day of the year [...]."
"The image [on the right] shows a sampling of what these different signals look like [...]. The left side of the figure shows the seismograms, the right side shows the frequency content of each seismogram."
"These earthquakes are tiny, smaller than Magnitude 0. Earthquakes this small are usually ignored because they are too small to locate or do anything useful with. What makes these quakes special is that the same earthquake occurs over and over again, up to thousands of times."
"When more than one earthquake have nearly identical seismograms, it means that the source is the same for both and their location remains stable over time."
"Glaciers actually generate most of the seismicity on the mountain. [...] these sequences have been happening on and off for the last two years as well as a few times in the 1990's and there hasn't been any volcanic activity".

## Geology

"Large Holocene mudflows from collapse of this massive, heavily glaciated andesitic volcano have reached as far as the Puget Sound lowlands. The present summit was constructed within a large crater breached to the northeast formed by collapse of the volcano during a major explosive eruption about 5600 years that produced the widespread Osceola Mudflow. Rainier has produced eruptions throughout the Holocene, including about a dozen during the past 2600 years; the largest of these occurred about 2200 years ago. The present-day summit cone is capped by two overlapping craters. Extensive hydrothermal alteration of the upper portion of the volcano has contributed to its structural weakness; an active thermal system has caused periodic melting on flank glaciers and produced an elaborate system of steam caves in the summit icecap."
"Around 500,000 years ago, Mount Rainier started to grow atop the eroded remains of an earlier ancestral Mount Rainier that was active 1-2 million years ago. The modern edifice grew as a series of four alternating stages [Old Desolate, Rampart, Mowich, and Little Tahoma] of volcanic activity [see the image on the right], averaging a little more than 100,000 years duration. During stages of high output lava flows travelled up to 24 km (15 mi) from the summit, and in times of modest volcanic output, including today, the lava flows rarely exceed 8 km (5 mi) from the summit. Glaciers deeply filled the surrounding valleys over most of the volcano's history. The style of volcanic activity remains the same, with no evidence of diminution."

## Geomorphology

In the center of the top panorama above is the Kautz Ice Cliff of the south face of Mount Rainier.
The second image down from above is 3D with names and labels many features around Mount Rainier.
The image on the right is a view of the northwest face of Mount Rainier.

## Landslides

The image on the right shows the deposition of sediment from the 1963 debris avalanche below the Emmons.
On the left, originating at Kautz Glacier on Mount Rainier, Washington, flowing down Comet Falls is the 2001 Van Trump Creek debris flow.
"Almost annually, torrential rain, glacial outbursts, and water-saturation of steep debris-covered slopes cause debris flows at Mount Rainier. Debris flows such as these develop when floods of water generated by meteorological or hydrologic events erode and incorporate the unconsolidated glacial and volcanic debris that mantles the slopes and upper drainages of the volcano."
"In summer 2001 during a period of fair weather, debris flows in Van Trump Creek caught everyone by surprise when they came roaring under a highway bridge and past a popular campground. The cause of the debris flows was a small stream of water from Kautz Glacier that topped a drainage divide and saturated glacial sediments of upper Van Trump Park on the volcano's south side. Water-saturated debris slid away in succession to form a series of debris flows that swept more than four miles down Van Trump Creek to the confluence of the Nisqually River, raising the stream channel to an elevation above the nearby roadbed."

## Glaciology

"Mount Rainier has the largest number of glaciers on a single peak anywhere in the contiguous United States. The 25 glaciers have a combined area of 90 square kilometers (35 square miles), which means that almost 10% of the park is covered by glacier."
"The combined volume of the glaciers is estimated to be 4.2 cubic kilometers (1.0 cubic miles)."
Mount Rainier has the following glaciers around it:
* Carbon Glacier,
* Cowlitz Glacier
* Edmunds Glacier,
* Emmons Glacier,
* Fleet Glacier,
* Frying Pan Glacier,
* Ingraham Glacier,
* Inter Glacier,
* Kautz Glacier,
* Muir Snowfield,
* Nisqually Glacier,
* North Mowich Glacier,
* Ohanapecosh Glacier,
* Paradise-Stevens Glacier,
* Puyallup Glacier,
* Pyramid Glacier,
* Russell Glacier,
* Sarvent Glacier,
* South Mowich Glacier,
* South Tahoma Glacier,
* Summit,
* Tahoma Glacier,
* Van Trump Glacier,
* Whitman Glacier,
* Wilson Glacier, and
* Winthrop Glacier.

## Carbon Glacier

On the right is the Carbon Glacier accumulation zone with Willis Wall behind. The photo on the left is the front end or toe of the Carbon Glacier.

## Emmons Glacier

"Mount Rainier rises above Yakima Park on the north side of the volcano. Emmons Glacier [shown in the first image on the right in 2013] descends to the left from the summit within a broad valley between Little Tahoma Peak at the extreme left and the low ridge descending diagonally to the left at the center of the photo [on the top left from 1972]. This 2.5-km-wide valley was created when Mount Rainier collapsed about 5700 years ago, forming the Osceola mudflow, which traveled all the way to the Puget Sound. The collapse was associated with an explosive eruption."
The image on the top left gives a better view of the 2.5-km-wide valley.
The second image on the right is a closeup of Emmons Glacier from Camp Curtis on Steamboat Prow.
The second image down on the left is a closeup of Emmons Glacier with mountaineers for scale; "large seracs and crevasses. The brown tint of the ice surface is due to dust from nearby rock slides on Russell Cliff and Curtis Ridge."

## Frying Pan Glacier

Fryingpan Glacier [image on the right, second down] has coordinates 46°50'32"N 121°41'27"W.

## Ingraham Glacier

In the image on the right, "Ingraham Glacier (left) is between Gibraltar Rock (12660 feet) center skyline and Disappointment Cleaver (upper right). Left of Gibraltar Rock is sharp pointed Little Tahoma (11138 feet) with Frying Pan Glacier on its flank."

## Inter Glacier

The image on the right shows a red arrow pointing towards the red, outlined terminus of the Inter Glacier. The green line is its terminus in 2009.
"In 1992-1994 the glacier extends below a prominent knob on the east side of the glacier, red arrow."
"Inter Glacier is one of the smaller glaciers on Mount Rainier, Washington, lying between the larger Emmons and Winthrop Glacier. The glacier now extends from 2800 to 2200 m, with recent retreat shortening the glacier to 1 km in length."
"By 2009 the glacier has thinned considerably and retreated 200 m, terminus indicated by green line."

## Kautz Glacier

In the image on the right, Kautz Glacier is left of center with its lower portion down an ice wall.

## Muir Snowfield

Muir Snowfield is at the center of the image on the right.

## Nisqually Glacier

"Sunlight catches the lower part of the Nisqually Glacier at the lower right-center [in the image on the right]; the glacier descends in a series of icefalls [one is shown in the image on the left] more than 3000 vertical meters from the summit icecap. Meadows and forests of the Paradise area lie immediately below and to the right of the glacier. Camp Muir, used as base for climbs of Rainier, is at the top of the snowfield below and to the right of the massive cliffs of Gibralter Rock on the right skyline."

## North Mowich Glacier

The image on the right shows "the glacier-clad NW flank of Mount Rainier [...]. The North Mowich Glacier in the center of the photo descends to about 1500 m elevation."

## Ohanapecosh Glacier

The image on the right shows the Ohanapecosh Glacier. The viewpoint elevation is 2104 m, with a viewing direction looking south-southwest from Banshee Peak climbers route.

## Russell Glacier

The image on the right shows the Russell Glacier ablation zone with Carbon Glacier behind.

## Tahoma Glacier

"The Tahoma Glacier spills from the summit icecap of Mount Rainier between Liberty Cap (left) and Point Success (right) in this aerial view [image on the left] from the SW. Two young cinder cones, constructed within a scarp left by massive collapse of the summit of Mount Rainier about 5700 years ago, form the present-day summit of the volcano. Slope failure of the summit or upper flanks of the hydrothermally altered volcano has occurred several times during the Holocene, producing massive debris avalanches and mudflows that swept into the Puget lowlands."

## Whitman Glacier

In the image on the right, Whitman Glacier is the main body of ice in the center.

## Winthrop Glacier

"The massive 4392-m-high glacier-mantled cone of Mount Rainier forms the highest peak of the Cascade Range. This aerial view from the NW [the first and second images on the right] also shows neighboring Mount Adams on the right horizon. The steep cirque forming the sheer Willis Wall [indicated in the first image on the right], named after the 19th-century geologist Bailey Willis, lies in the shadow at the left, below the Winthrop Glacier, which forms the left-hand ridge of Mount Rainier. Two young overlapping cinder cones, their rims kept free of snow by high heat flow, form the flat summit of the volcano."
On the left is a closeup of the Winthrop Glacier with seracs and crevasses. "The brown tint of the ice [may be] due to dust from nearby rock slides."

## Theory of Mount Rainier

Mount Rainier is a stratovolcano in the volcanic region: Canada and Western USA.
It has been assigned Volcano Number 321030.
The diagram above shows a generalized "north-south geologic cross-section through Mount Rainier National Park [with] the central vent, glaciers, Tatoosh pluton, and adjacent bedded strata."
"Different tectonic models have been proposed for the development of the Cascades, but all models include subduction, addition of exotic terranes, and oblique plate movements as important components in creating today’s Cascade Range (Kiver and Harris, 1999). In general, the North American plate edge was located farther east during the Mesozoic in Nevada, western Idaho, and eastern Washington. Subduction processes added larger masses of continental materials, island-like masses called microcontinents, microplates, or exotic terranes to the western margin of North American. Addition of these microplates shifted the plate edge westward."
"About 9 Ma (late Miocene), the rate of collision between lithospheric plates slowed and the angle of descent of the subducting plate steepened, like it is today [...]. In the Miocene and Pliocene, a great upward surge of molten rock [the Tatoosh Pluton labeled in the diagram above] stopped short of the surface and intruded the rocks of the Ohanapecosh, Stevens Ridge, and Fifes Peak Formations, solidifying as intrusive igneous bodies, called plutons [in the figure above center] (Fiske et al., 1963, 1988). Dikes and sills riddle the bedded formations. Some of these intrusive bodies are large enough to be mapped; some are not. Some of the magma erupted onto the surface although all but the welded tuff at The Palisades has been eroded from the park."
"Igneous activity such as eruption of the lava flow at Bee Flat occurred sporadically throughout the rest of the Pliocene time. But uplift and erosion were the dominant processes at the time, and these processes developed the unconformity that separates the Pliocene from the Pleistocene (Map Unit Properties Table). Over time, the thin roof of older rocks was partly eroded away to expose the top of a large and complex granitic pluton. Some of the best exposures are found in the rugged cirques and peaks of the Tatoosh Range, from which the pluton is named [...]. The granodiorite of the Tatoosh pluton is also exposed in the Carbon and White River valleys and part of the upper Nisqually River valley. Mapping reveals that the Tatoosh pluton completely underlies Mount Rainier and forms a platform upon which the volcano grew [in the diagram above] (Fiske et al., 1988)."

## Location

Mount Rainier is on the land surface of Earth: latitude 46.853°N, longitude 121.76°W.

## Eruptions

106 b2k: last known eruption: 21 November 1894 to 24 December 1894 at VEI = 1 from historical observations.
550±100 b2k: confirmed by corrected radiocarbon dating.
1090±500 b2k: confirmed by corrected radiocarbon dating.
1560±100 b2k: confirmed by corrected radiocarbon dating.
2150 (?) b2k: confirmed by tephrochronology.
2250±200 b2k: confirmed by corrected radiocarbon dating. VEI = 4.
2400±50 b2k: confirmed by tephrochronology.
2500±50 b2k: confirmed by tephrochronology.
2610±100 b2k: confirmed by corrected radiocarbon dating.
2650±50 b2k: confirmed by tephrochronology.
2700±50 b2k: confirmed by tephrochronology.
4550 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 3.
4750 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 2.
5650 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 3.
5850±200 b2k: confirmed by corrected radiocarbon dating.
6850 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 2.
7050 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 3.
7350 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 3.
7550 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 2.
9800±300 b2k: confirmed by corrected radiocarbon dating.
10,050 (?) b2k: confirmed by corrected radiocarbon dating. VEI = 3.

## Craters

Def. a "hemispherical pit ... [a] basinlike opening or mouth ... about which a cone is often built up ... any large roughly circular depression or hole" is called a crater.
Columbia Crest, East Crater, and West Crater are craters atop Mount Rainier.
The image on the right shows Columbia Crest at the center top of this photo of Mount Rainier, its main summit.
"Emmons Glacier covers most of the visible flank of the mountain. Ingraham Glacier (left) is between Gibraltar Rock (12660 feet [3859 m]) high on the left skyline and Disappointment Cleaver. Left of Gibraltar Rock is sharp pointed Little Tahoma (11138 feet [3395 m]) with Frying Pan Glacier on its flank. It is the source of Frying Pan Creek in the valley left of forested and rounded Goat Island Mountain, in front of the Emmons Glacier. Liberty Cap (14112 feet [4302 m]) is visible on the right center skyline behind Russell Cliff. Curtis Ridge descends to the right from Russell Cliff. Winthrop Glacier flows right below Curtis Ridge and behind shallow Steamboat Prow (9680 feet [2951 m]) with the small Inter Glacier on its northeast face. The White River comes from the Emmons Glacier and flows around the right side of Goat Island Mountain in the watercourse visible below right."

## Volcanic activity

On the right is a diagram of various volcanic, or volcanism induced, flows, or likely flows, around Mount Rainier.
"Flat-topped Burroughs Mountain [in the second image down on the right] on the NE flank of Mount Rainier is underlain by a massive andesitic lava flow. The 3.4 cu km flow is up to 350 m thick and extends 11 km from about 2350 m to 1300 m elevation. The flow was erupted about 500,000 years ago at the onset of a period initial growth of modern Mount Rainier volcano and overlies block-and-ashflow deposits. The flow is perched on a ridge top and has ice-contact features, indicative of its emplacement against the margins of a thick Pleistocene glacier."
Disappointment Cleaver is a thermal feature of Mount Rainier.

## Stratigraphy

On the right is a summary stratigraphic section of thick, prominent Holocene tephra-fall deposits from Mount Rainier (pink to red colors).
"Eruptions [of Mount Rainier] group into 4 eruptive periods and several isolated episodes between about 11,000 years ago and now."
"Several eruptions [during the Sunrise eruptive period 11,000 b2k] deposited volcanic ash and pumice across the eastern portion of Mount Rainier National Park. At least one lahar, apparently of landslide origin, moved across Van Trump and Paradise Parks and then down the Nisqually River. Tephra layers indicate isolated eruptions a thousand and more years after the chief eruptive events."
"A number of tephra layers [deposited during the Cowlitz Park eruptive period 7,400 to 6,700 b2k] in alpine meadows east of the volcano indicate a succession of eruptions, at least 4 of which were moderately explosive, distributed pumice and ash downwind, and produced lahars that descended the White and Nisqually River valleys. Interaction of hot pyroclastic rock with snow and ice probably caused three or more lahars, one of which traveled along the White River and South Prairie Creek as far as Orting 70 km (43 miles) downstream. Around 7,300 years ago, an eruption produced a thin ash layer and caused a collapse of hyrdothermally altered rock on the south flank of the volcano. The collapse generated the Reflection Lakes lahar that swept across the Paradise area and down the Nisqually River valley; the lahar also spilled over a low divide in Mazama Ridge and moved as far as Reflection Lakes. Deposits of the lahar now crop out in cuts along Skyline and Golden Gate trails above Panorama Point and nearly to the crest of Mazama Ridge."
"One to two hundred years prior to the Osceola Mudflow, a portion of the edifice collapsed to produce the Paradise lahar, which swept down the mountain's south side along the Nisqually River at least as far as the village of National. Deposits now crop out in the Paradise area but not to such high levels as those of the previous Reflection Lakes lahar."
"About 5600 years ago [the beginning of the Osceola eruptive period] Mount Rainier's seminal postglacial event occurred on its northeastern flank and summit when an eruption triggered an edifice collapse of weakened hydrothermally altered rock that contained sufficient widely dispersed water from the hydrothermal system to generate the enormous, 4 km$^3$ (1 mi$^3$) Osceola Mudflow. The lahar washed across Steamboat Prow and Glacier Basin and then ran up to about the 6400-foot level of Goat Island Mountain and Sunrise Ridge. It then descended the White River valley 80 to 150 m (260- 490 ft) deep, spread out over 210 km$^2$ (82 mi$^2$) of Puget Sound Lowland 70-100 km (44-62 mi) from source, and flowed into Puget Sound, moving underwater up to 20 km (12.4 mi) to the present sites of Tacoma and the Seattle suburb of Kent. The contemporaneous phreatic and phreatomagmatic explosive eruptions blew hydrothermal clay and mud northeastward across Sunrise Ridge and spread pumice across an arc from south to northeast of the volcano. The Osceola edifice collapse left a horseshoe-shaped crater open to the northeast at Mount Rainier, much like the open crater formed at Mount St. Helens in 1980."
"After the Osceola Mudflow, the White River abandoned its old course flowing westward along South Prairie Creek and established a new channel flowing northwestward across the lowland to Puget Sound. Much of the Duwamish arm of Puget Sound was filled in as a result of post-Osceola erosion and sedimentation. The upper White River system responded with tens of meters of aggradation. At the volcano, numerous subsequent, thin tephra layers suggest sporadic cone building during a period of several hundred years."
"About 2,700 years ago Mount Rainier began to erupt again [during the Summerland eruptive episode], producing tephra and lahars that flowed northeastward into the White River valley. Within a few tens of years, resumed eruptions generated tephra, lahars to the northeast, and a landslide-induced lahar called the Round Pass mudflow, which swept westward into the Puyallup River drainage and the Nisqually River drainage via Tahoma Creek. Continued growth of the edifice during this period opened previously cutoff drainages to the west and south to flows originating from the summit. A sequence of tephra falls, pyroclastic flows and lahars followed, indicating continued eruptions separated by time intervals ranging from several tens to hundreds of years. Next Summerland lava flows descended from the summit area's west crater and now underlie much of the upper Emmons, Winthrop and Tahoma Glaciers. The upper portion of Camp Schurman sits atop lava erupted from the summit at this time. The largest Holocene tephra eruption (Layer C: ∼0.1 to 0.2 km$^3$ or 0.02 to 0.04 mi$^3$) occurred about 2,200 years ago. It covers areas near Sunrise visitor center, as well as Burroughs Mountain. Lahars caused by the layer-C eruption descended the White, Cowlitz, and Nisqually River drainages. Summerland lahars and associated sediment accumulated to depths of several meters thickness at sites as far downstream as Auburn and downstream along the Duwamish River toward Elliott Bay. Lava flows that rim Mount Rainier's east crater, Columbia Crest, followed the eruption of layer C. By the end of the Summerland eruptive period the summit of Mount Rainier had grown to its present form and altitude."
"Several thin ash deposits [during the Twin Creek eruptive episode, 1,500 b2k] restricted to sub-alpine meadows and far-traveled lahars of the Twin Creeks assemblage show that small eruptions took place about 1,500 years ago. Although these events involved the eruption of new magma, no lava flows were produced."
"About 1,100 years ago [during the Fryingpan Creek eruptive period], one or possibly two lahars flowed down the White River as far as Auburn. These lahars may have been generated as pyroclastic flows descended the Emmons and Winthrop Glacier and incorporated and melted snow and ice. Reworking of the lahar sediment caused extensive aggradation of the Duwamish River valley as far as Puget Sound and the southernmost Seattle suburbs. No lava flows were erupted."
"Around 500 years ago, an avalanche of hydrothermally altered rock from the west side of Mount Rainier caused a lahar known as the Electron Mudflow (0.26 km$^3$ or 0.06 mi$^3$) that swept down the Puyallup drainage at least as far as Sumner. There is no evidence to indicate whether an eruption or some other event triggered the lahar. Somewhat younger lahars descended the Nisqually and White River drainages at about this time."

## Hypotheses

* The time between eruptions of Mount Rainier has been increasing since its creation.