What is the largest glacier on Mount Rainier?
191265#1
Mount Rainier is circled by the Wonderland Trail and is covered by glaciers and snowfields totaling about . Carbon Glacier is the largest glacier by volume in the contiguous United States, while Emmons Glacier is the largest glacier by area. Mount Rainier is a popular peak for mountaineering with some 10,000 attempts per year with approximately 50% making it to the summit.
Mount Rainier National Park
1427181#0
Emmons Glacier is on the northeast flank of Mount Rainier, in Washington. At , it has the largest surface area of any glacier in the contiguous United States. The glacier was named after the geologist Samuel Franklin Emmons after his involvement in a survey of Mount Rainier in 1870.
Emmons Glacier
21251533#36
Mountain climbing on Mount Rainier is difficult, involving traversing the largest glaciers in the U.S. south of Alaska. Most climbers require two to three days to reach the summit, with a success rate of approximately 50%, with weather and physical conditioning of the climbers being the most common reasons for failure. About 8,000 to 13,000 people attempt the climb each year, about 90% via routes from Camp Muir on the southeast flank, and most of the rest ascend Emmons Glacier via Camp Schurman on the northeast. Climbing teams require experience in glacier travel, self-rescue, and wilderness travel. All climbers who plan to climb above the high camps, Camp Muir and Camp Schurman, are required by law to purchase a Mount Rainier Climbing Pass and register for their climb. 
Additionally, solo climbers must fill out a solo climbing request form and receive written permission from the Superintendent before attempting to climb.
Mount Rainier
21251533#24
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 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 of the White River Campground.
Mount Rainier
21251533#43
The worst mountaineering accident on Mount Rainier occurred in 1981, when eleven people lost their lives in an ice fall on the Ingraham Glacier.
This was the largest number of fatalities on Mount Rainier in a single incident since 32 people were killed in a 1946 plane crash on the South Tahoma Glacier.
Mount Rainier
11285624#0
The Wilson Glacier is a medium-sized tributary glacier located on the southeast flank of Mount Rainier in Washington. Named after A.D. Wilson, who was part of an early ascent of Mount Rainier, the body of ice has an area of and has a volume of 1.9 billion feet (54 million m). The glacier is directly feeds ice to the adjacent, but much larger Nisqually Glacier. Starting from the head at , the glacier flows downhill southward. One part of the glacier meets the Nisqually Glacier at and the other part of the glacier ends on a cliff in between the Wilson and Nisqually Glacier at . Meltwater from the glacier feeds the Nisqually River.
Wilson Glacier (Mount Rainier)
21251533#9
With 26 major glaciers and of permanent snowfields and glaciers, Mount Rainier is the most heavily glaciated peak in the lower 48 states. The summit is topped by two volcanic craters, each more than 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 cave network within the ice-filled craters, with nearly of passages.
A small crater lake about in size and deep, the highest in North America with a surface elevation of , occupies the lowest portion of the west crater below more than of ice and is accessible only via the caves.
Mount Rainier
11285332#0
The Russell Glacier is a medium-sized glacier on the north flank of Mount Rainier, Washington. Named for the geologist Israel Russell, it covers and contains 3.1 billion ft (88 million m) of ice. Starting from its highest point at , the Russell Glacier flows northeast towards the Carbon Glacier and contributes ice to the larger glacier before becoming distinct below . With most of the ice located from to , the glacier only descends to , unlike the much lower extent of the Carbon Glacier. Echo Rock and Observation Rock, two minor sub-peaks of Rainier, lie northwest of this glacier. Meltwater from the glacier eventually reaches the Carbon River.
Russell Glacier (Mount Rainier)
8535323#0
The Nisqually Glacier is one of the larger glaciers on the southwestern face of Mount Rainier in the U.S. state of Washington. The glacier is one of the most easily viewed on the mountain, and is accessible from the Paradise visitor facilities in Mount Rainier National Park. The glacier has had periods of advance and retreat since 1850 when it was much more extensive. It is currently retreating. Measurements made at altitude show that glacier got thicker between 1994 and 1997, suggesting that it will probably begin advancing in the first decade of the 21st century. Nisqually Glacier is the source of the Nisqually River.
Nisqually Glacier
21251533#18
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 Saint Helens, Mount Adams, Glacier Peak, and Mount Baker in Washington, and Mount Cayley, Mount Garibaldi, Silverthrone Caldera, and Mount Meager in British Columbia. All 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 behave and what they are capable of in the future, including Mount Rainier. Of these, only two have 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 have 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, and Mt. Rainier's closest neighbor, Mount St. Helens, produced the largest 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.
Mount Rainier is currently listed as a Decade Volcano, or one of the 16 volcanoes with the greatest likelihood of causing great loss of life and property if eruptive activity resumes. If Mt. 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, the vastly more heavily populated areas surrounding Rainier, and the simple fact that Mt Rainier is a much bigger volcano, almost twice the size of St. Helens. Lahars from Rainier pose the most risk to life and property, 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. 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 Osceola mudflow would destroy Enumclaw, Orting, Kent, Auburn, Puyallup, Sumner and all of Renton. 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. Rainier is also capable of producing pyroclastic flows and expelling lava.
According to K. Scott, a scientist with the USGS:
Mount Rainier