Mount RainierTahomaMount Rainier's northwestern slope viewed aerially just before sunset on September 6, 2020Highest pointElevation14,410 feet (4,390 m) (1956)[1][2]Prominence13,210 ft (4,030 m)[3]Isolation731 mi (1,176 km)[4]ListingWorld most prominent peaks 21stNorth America prominent peaks 4thNorth America isolated peaks 7thU.S. highest major peaks 17thU.S. state high point 4thDecade VolcanoCoordinates46°51′6″N 121°45′37″W / 46.85167°N 121.76028°W / 46.85167; -121.76028[5][4]NamingEtymologyPeter RainierGeographyMount Rainier CountryUnited StatesStateWashingtonCountyPierce CountyProtected areaMount Rainier National ParkParent rangeCascade RangeTopo mapUSGS Mount Rainier WestGeologyFormed bySubduction zone volcanismRock age500,000 yearsMountain typeStratovolcanoVolcanic arcCascade Volcanic ArcLast eruption1450[6]ClimbingFirst ascent1870 by Hazard Stevens and P. B. Van TrumpEasiest routerock/ice climb via Disappointment Cleer
Mount Rainier[a] (/reɪ.ˈnɪər/ ray-NEER), also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles (95 km) south-southeast of Seattle.[11] At 14,410 feet[b] (4,390 m) it is the highest mountain in the U.S. state of Washington, the most topographically prominent mountain in the contiguous United States,[3] and the tallest in the Cascade Volcanic Arc.
Due to its high probability of an eruption in the near future and proximity to a major urban area, Mount Rainier is considered one of the most dangerous volcanoes in the world, and it is on the Decade Volcano list.[14] The large amount of glacial ice means that Mount Rainier could produce massive lahars that could threaten the entire Puyallup River valley and other river valleys draining Mount Rainier, including the Carbon, White, Nisqually, and Cowlitz (above Riffe Lake).[15] According to the United States Geological Survey's 2008 report, "about 80,000 people and their homes are at risk in Mount Rainier's lahar-hazard zones."[16]
Between 1950 and 2018, 439,460 people climbed Mount Rainier.[17][18] Approximately 84 people died in mountaineering accidents on Mount Rainier from 1947 to 2018.[17]
Name[edit] Mount Rainier seen from the International Space StationThe many Indigenous peoples who he lived near Mount Rainier for millennia he many names for the mountain in their various languages. A linguistic analysis published in 2025 identified 20 names in indigenous languages for the mountain.[19]
Lushootseed speakers he several names for Mount Rainier, including xʷaq̓ʷ[pronunciation?] and təqʷubəʔ.[c][7] xʷaq̓ʷ means "sky wiper" or "one who touches the sky" in English.[7] The word təqʷubəʔ means "snow-covered mountain".[7][8] təqʷubəʔ has been anglicized in many ways, including "Tacoma" and "Tacobet".[20]
Cowlitz speakers call the mountain təx̣ʷúma[pronunciation?] or təqʷúmen.[pronunciation?][9] Sahaptin speakers call the mountain Tax̱úma, which is borrowed from Cowlitz.[10]
Another anglicized name is Pooskaus.[21][clarification needed]
George Vancouver named Mount Rainier in honor of his friend, Rear Admiral Peter Rainier.[22] The map of the Lewis and Clark expedition of 1804–1806 refers to it as "Mt. Regniere". Although Rainier had been considered the official name of the mountain, Theodore Winthrop referred to the mountain as "Tacoma" in his posthumously published 1862 trel book The Canoe and the Saddle. For a time, both names were used interchangeably, although residents of the nearby city of Tacoma preferred Mount Tacoma.[23][24]
In 1890, the United States Board on Geographic Names declared that the mountain would be known as Rainier.[25] Following this in 1897, the Pacific Forest Reserve became the Mount Rainier Forest Reserve, and the national park was established three years later. Despite this, there was still a movement to change the mountain's name to Tacoma and Congress was still considering a resolution to change the name as late as 1924.[26][27]
Geographical setting[edit] West face of Mount Rainier from an aircraftMount Rainier is the tallest mountain in Washington and the Cascade Range. This peak is located southeast of Tacoma, approximately 60 miles (97 km) south-southeast of Seattle.[28][29] Mount Rainier has a topographic prominence of 13,210 ft (4,026 m).[3] On clear days it dominates the southeastern horizon in most of the Seattle-Tacoma metropolitan area to such an extent that locals sometimes refer to it simply as "the Mountain".[30][31] On days of exceptional clarity, it can also be seen from as far away as Corvallis, Oregon (at Marys Peak), and the North Shore Mountains in British Columbia.[32][33]
With 26 major glaciers[34] and 36 sq mi (93 km2) of permanent snowfields and glaciers,[35] Mount Rainier is the most heily glaciated peak in the lower 48 states. The summit is topped by two volcanic craters, each more than 1,000 ft (300 m) in diameter, with the larger east crater overlapping the west crater. Geothermal heat from the volcano keeps areas of both crater rims free of snow and ice, and has formed the world's largest volcanic glacier ce network within the ice-filled craters,[36] with nearly 2 mi (3.2 km) of passages.[37] A small crater lake about 130 by 30 ft (39.6 by 9.1 m) in size and 16 ft (5 m) deep, the highest in North America with a surface elevation of 14,203 ft (4,329 m), occupies the lowest portion of the west crater below more than 100 ft (30 m) of ice and is accessible only via the ces.[38][39]
The Carbon, Cowlitz, Nisqually, Puyallup River, and North Mowich Rivers begin at eponymous glaciers of Mount Rainier.[40] The sources of the White River are Winthrop, Emmons, and Fryingpan Glaciers.[40] The White, Carbon, and Mowich join the Puyallup River, which discharges into Commencement Bay at Tacoma.[41] The Nisqually empties into Puget Sound east of Lacey.[42] The Cowlitz joins the Columbia River between Kelso and Longview.[43]
A panorama of the northeast face of Mount Rainier Subsidiary peaks[edit] Little Tahoma Peak to the left of Mount Rainier, from Panhandle GapThe broad top of Mount Rainier contains three named summits. The highest of these named summits is known as the Columbia Crest. The second highest summit is Point Success, 14,158 ft (4,315 m), at the southern edge of the summit plateau, atop the ridge known as Success Cleer. It has a topographic prominence of about 138 ft (42 m), so it is not considered a separate peak. The lowest of the three summits is Liberty Cap, 14,112 ft (4,301 m), at the northwestern edge, which overlooks Liberty Ridge, the Sunset Amphitheater, and the dramatic Willis Wall.[44]
High on the eastern flank of Mount Rainier is a peak known as Little Tahoma Peak, 11,138 ft (3,395 m), an eroded remnant of the earlier, much higher, Mount Rainier. It has a prominence of 858 ft (262 m), and it is almost never climbed in direct conjunction with Columbia Crest, so it is usually considered a separate peak. If considered separately from Mount Rainier, Little Tahoma Peak would be the third highest mountain peak in Washington.[45]
Height of the mountain[edit]Mount Rainier was one of five historical icecap summits in the lower 48 states, meaning that its elevation has changed as a result of glacial melting due to climate change.[1] The National Park Service and United States Geological Survey cite Mount Rainier's summit as the Columbia Crest icecap at 14,410 ft (4,392 m);[2][46] this value was determined in 1956, referenced to the National Geodetic Vertical Datum of 1929 (NGVD29).[47] In 1999, the mountain summit was surveyed at 14,411 ft (4,392 m), also in the NGVD29.[d][47][48]
In the 2020s, Eric Gilbertson and other surveyors found that the Columbia Crest had melted down so that it was no longer the highest point on the mountain after around 2014. According to Gilbertson's research, the current summit of the mountain is a point of bare rock on the southwest crater rim at 14,399.6 feet (4,389.0 m) +/- 3 cm (1.2 in). This figure also uses the NGVD29 datum.[1] Mount Rainier National Park geologists expressed concerns over the methods used in the study and requested the data for evaluation, though they recorded similar glacial thinning. An official measurement taken in 2010 saw little to no change from the official value.[49]
Geology[edit] Hazard mapMount Rainier is a stratovolcano in the Cascade Volcanic Arc that consists of la flows, debris flows, and pyroclastic ejecta and flows. Its early volcanic deposits are estimated at more than 840,000 years old and are part of the Lily Formation (about 2.9 million to 840,000 years ago). The early deposits formed a "proto-Rainier" or an ancestral cone prior to the present-day cone.[50] The present cone is more than 500,000 years old.[51]
The volcano is highly eroded, with glaciers on its slopes, and appears to be made mostly of andesite. Rainier likely once stood even higher than today at about 16,000 ft (4,900 m) before a major debris alanche and the resulting Osceola Mudflow approximately 5,000 years ago.[52] In the past, Rainier has had large debris alanches, and has also produced enormous lahars (volcanic mudflows), due to the large amount of glacial ice present. Its lahars he reached all the way to Puget Sound, a distance of more than 30 mi (48 km). Around 5,000 years ago, a large chunk of the volcano slid away and that debris alanche helped to produce the massive Osceola Mudflow, which went all the way to the site of present-day Tacoma and south Seattle.[53] This massive alanche of rock and ice removed the top 1,600 ft (500 m) of Rainier, bringing its height down to around 14,100 ft (4,300 m). About 530 to 550 years ago, the Electron Mudflow occurred, although this was not as large-scale as the Osceola Mudflow.[54]
After the major collapse approximately 5,000 years ago, subsequent eruptions of la and tephra built up the modern summit cone until about as recently as 1,000 years ago. As many as 11 Holocene tephra layers he been found.[50]
Soils on Mount Rainier are mostly grelly ashy sandy loams developed from colluvium or glacial till mixed with volcanic tephra. Under forest cover their profiles usually he the banded appearance of a classic podzol but the E horizon is darker than usual. Under meadows a thick dark A horizon usually forms the topsoil.[55]
Modern activity and threat[edit] The summit of Mount Rainier showing summit calderas and the mountain's glaciers.The most recent recorded volcanic activity was between 1820 and 1854, but many eyewitnesses reported eruptive activity in 1858, 1870, 1879, 1882, and 1894 as well.[56] Additionally, the Smithsonian Institution's volcanism project records the last volcanic eruption as 1450 CE.[6]
Seismic monitors he been placed in Mount Rainier National Park and on the mountain itself to monitor activity.[57] An eruption could be deadly for all living in areas within the immediate vicinity of the volcano and effects from an eruption could be noticed from Vancouver, British Columbia to San Francisco, California,[58] because of the massive amounts of ash blasting out of the volcano into the atmosphere.
Mount Rainier is located in an area that itself is part of the eastern rim of the Pacific Ring of Fire. This includes mountains and calderas like Mount Shasta and Lassen Peak in California, Crater Lake, Three Sisters, and Mount Hood in Oregon, Mount St. Helens, Mount Adams, Glacier Peak, and Mount Baker in Washington, and Mount Cayley, Mount Garibaldi, Silverthrone Caldera, and Mount Meager in British Columbia. Many of the above are dormant, but could return to activity, and scientists on both sides of the border gather research of the past eruptions of each in order to predict how mountains in this arc will behe and what they are capable of in the future, including Mount Rainier.[59][60] Of these, two he erupted since the beginning of the twentieth century: Lassen in 1915 and St. Helens in 1980 and 2004. However, past eruptions in this volcanic arc he multiple examples of sub-plinian eruptions or higher: Crater Lake's last eruption as Mount Mazama was large enough to cause its cone to collapse,[61] and Mount Rainier's closest neighbor, Mount St. Helens, produced the largest recorded eruption in the continental United States when it erupted in 1980. Statistics place the likelihood of a major eruption in the Cascade Range at 2–3 per century.[62]
One of many emergency evacuation route signs in case of volcanic eruption or lahar around Mount RainierMount Rainier is listed as a Decade Volcano, or one of the 16 volcanoes on Earth with the greatest likelihood of causing loss of life and property if eruptive activity resumes.[63] If Mount Rainier were to erupt as powerfully as Mount St. Helens did in its May 18, 1980 eruption, the effect would be cumulatively greater, because of the far more massive amounts of glacial ice locked on the volcano compared to Mount St. Helens,[54] the vastly more heily populated areas surrounding Rainier, and the fact that Mount Rainier is almost twice the size of St. Helens.[64] Lahars from Rainier pose the most risk to life and property,[65] as many communities lie atop older lahar deposits. According to the United States Geological Survey (USGS), about 150,000 people live on top of old lahar deposits of Rainier.[16] Not only is there much ice atop the volcano, the volcano is also slowly being weakened by hydrothermal activity. According to Geoff Clayton, a geologist with a Washington State Geology firm, RH2 Engineering, a repeat of the 5000-year-old Osceola Mudflow would destroy Enumclaw, Orting, Kent, Auburn, Puyallup, Sumner and all of Renton.[53] Such a mudflow might also reach down the Duwamish estuary and destroy parts of downtown Seattle, and cause tsunamis in Puget Sound and Lake Washington.[66] Rainier is also capable of producing pyroclastic flows and expelling la.[66] A 2012 Washington State Department of Natural Resources estimate showed that a significant lahar could cause up to $40 billion in damage downriver.[67]
According to Kevin Scott, a scientist with the USGS:
A home built in any of the probabilistically defined inundation areas on the new maps is more likely to be damaged or destroyed by a lahar than by fire... For example, a home built in an area that would be inundated every 100 years, on the erage, is 27 times more likely to be damaged or destroyed by a flow than by fire. People know the danger of fire, so they buy fire insurance and they he smoke alarms, but most people are not aware of the risks of lahars, and few he applicable flood insurance.[68]
The volcanic risk is somewhat mitigated by lahar warning sirens and escape route signs in Pierce County, part of the Mount Rainier Volcano Lahar Warning System, which was implemented by the USGS in 1998, and has been maintained by Pierce County since.[69] The more populous King County is also in the lahar area, but has no zoning restrictions due to volcanic hazard.[70] More recently (since 2001) funding from the federal government for lahar protection in the area has dried up, leading local authorities in at-risk cities like Orting to fear a disaster similar to the Armero tragedy.[71][72] To prevent against such tragedies, authorities downriver from Rainier he conducted annual large-scale evacuation exercises in cooperation with local school districts. The 2024 drill included 45,000 students and staff from the Puyallup, Sumner–Bonney Lake, Orting, White River, and Carbonado School Districts.[73] During the exercise, emergency operations centers in the cities of Puyallup, Bonney Lake, and Buckley were activated to help the movement of school students and staff.[74]
Seismic background[edit]Typically, up to five earthquakes are recorded monthly near the summit. Swarms of five to ten shallow earthquakes over two or three days take place from time to time, predominantly in the region of 13,000 feet (4 km) below the summit. These earthquakes are thought to be caused by the circulation of hot fluids beneath Mount Rainier. Presumably, hot springs and steam vents within Mount Rainier National Park are generated by such fluids.[75] Seismic swarms (not initiated with a mainshock) are common features at volcanoes, and are rarely associated with eruptive activity. Rainier has had several such swarms; there were days-long swarms in 2002, 2004, 2007, 2009,[76] 2011,[77] 2021,[78] and 2025. The 2025 swarm produced the largest number of events, highest rate of events, and largest amount of energy released since the monitoring began in 1982.[79]
Glaciers[edit] Three-dimensional representation of Mount Rainier Nisqually Glacier is seen clearly from the southeast of the mountain.Glaciers are among the most conspicuous and dynamic geologic features on Mount Rainier. They erode the volcanic cone and are important sources of streamflow for several rivers, including some that provide water for hydroelectric power and irrigation. Together with perennial snow patches, the 29 named glacial features cover about 30.41 square miles (78.8 km2) of the mountain's surface in 2015 and he an estimated volume of about 0.69 cubic miles (2.9 km3).[80][81][34][35]
Glaciers flow under the influence of grity by the combined action of sliding over the rock on which they lie and by deformation, the gradual displacement between and within individual ice crystals. Maximum speeds occur near the surface and along the centerline of the glacier. During May 1970, Nisqually Glacier was measured moving as fast as 29 inches (74 cm) per day. Flow rates are generally greater in summer than in winter, probably due to the presence of large quantities of meltwater at the glacier base.[35]
The size of glaciers on Mount Rainier has fluctuated significantly in the past. For example, during the last ice age, from about 25,000 to about 15,000 years ago, glaciers covered most of the area now within the boundaries of Mount Rainier National Park and extended to the perimeter of the present Puget Sound Basin.[35]
Between the 14th century and 1850, many of the glaciers on Mount Rainier advanced to their farthest extent downvalley since the last ice age. Many advances of this sort occurred worldwide during this time period known to geologists as the Little Ice Age. During the Little Ice Age, the Nisqually Glacier advanced to a position 650 to 800 ft (200 to 240 m) downvalley from the site of the Glacier Bridge, Tahoma and South Tahoma Glaciers merged at the base of Glacier Island, and the terminus of Emmons Glacier reached within 1.2 mi (1.9 km) of the White River Campground.[35]
The rocky area left behind after the retreat of the North Mowich Glacier seen in July 2024.Retreat of the Little Ice Age glaciers was slow until about 1920 when retreat became more rapid. The Williwakas Glacier was noted as extinct during the 1930s. Between the height of the Little Ice Age and 1950, Mount Rainier's glaciers lost about one-quarter of their length. Beginning in 1950 and continuing through the early 1980s, however, many of the major glaciers advanced in response to relatively cooler temperatures of the mid-century. The glaciers and snowfields of Mount Rainier also lost volume during this time, except for the Frying Pan and Emmons glaciers on the east flank and the small near-peak snowfields; the greatest volume loss was concentrated from ~1750 m (north) to ~2250 m (south) elevation. The largest single volume loss is from the Carbon Glacier, although it is to the north, due to its huge area at