What type of eruptions does mt rainier have

Some of the breccias were deposited by moving water, but others were probably emplaced during volcanic explosions or by fragmentation of moving lava flows. The volcano is located about 35 km southeast of the Seattle-Tacoma metropolitan area see Figure 2. This metropolitan area is the high-technology industrial center of the Pacific Northwest and one of the commercial-aircraft-manufacturing centers of the United States.

The rivers draining the volcano empty into Puget Sound, which has two major shipping ports, and into the Columbia River, a major shipping lane and home. The approximate outline of the volcano is indicated by the solid fill in Mount Rainier National Park. The locations of Puget Sound and the Seattle-Tacoma metropolitan area are indicated by dark and light stippling, respectively.

Also shown are the generalized locations of the dammed reservoirs on the White, Nisqually, and Cowlitz rivers after Swanson and others, Incorporated areas and areas with population densities greater than or equal to persons per square mile are shaded. In other areas, population densities are denoted with dots, each dot representing people courtesy of Carol Jenner, State of Washington Office of Financial Management.

Mount Rainier is an active volcano. It last erupted approximately years ago Mullineaux, , and numerous large floods and debris flows have been generated on its slopes during this century. More than , people live on the extensive mudflow deposits that have filled the rivers and valleys draining the volcano during the past 10, years Table 2. A major volcanic eruption or debris flow that is not prepared for could kill hundreds or thousands of residents and cripple the economy of the Pacific Northwest.

Despite the potential for such danger, Mount Rainier has received little study. Most of the geologic work on Mount Rainier was done more than two decades ago. Fundamental topics such as the development, history, and stability of the volcano are poorly understood. The recent eruptions of Mount St. Public awareness of natural hazards has been heightened by the recent recognition of an active fault crossing Seattle Atwater and Moore, ; Bucknam and others, ; Jacoby and others, ; Karlin and Abella, ; Schuster and others, , which is considered capable of generating an earthquake of magnitude 7 or greater.

As explained later, such an earthquake could trigger a catastrophic collapse of a portion of Mount Rainier's volcanic edifice. The term volcanic hazard is used here to refer to a volcanic or related events that pose a threat to persons or property in surrounding regions. Table 2. Also shown in the table are provisional estimates of risk, defined as the. Parentheses indicate volume less than 0. Risk depends in part on proximity to the hazard, which is defined here in terms of distance from the volcanic edifice.

The proximal zone refers to areas on and adjacent to the volcanic edifice. The distal zone refers to areas beyond the edifice that could be affected significantly by volcanic activity. For Mount Rainier, the distal zone includes areas up to about km outside of the National Park.

Risk also depends on the size magnitude of the event and its frequency of occurrence. In general, high-magnitude events pose greater risks to people and property than low-magnitude events. Relatively little is known about magnitudes and frequencies of volcanic events at Mount Rainier, so the estimates of risk shown in Table 2. Studies of the geologic history of Mount Rainier and other Cascades volcanoes see Chapter 3 in this report suggest that major volcanic hazards are likely to include the following:.

Volcanic eruptions. The eruption of lava flows and tephra particulate materials such as ash. Edifice failure. The gravitational collapse of a portion of the volcano. The sudden release of meltwater from glaciers and snowpack or from glacier-dammed lakes on the edifice.

Lahars, or debris flows, and debris avalanches. Gravitational movement of commonly water-saturated volcanic debris down the steep slopes of the volcano and into nearby valleys. The most likely volcanic hazards at Mount Rainier are from debris avalanches, lahars, and floods like those of the past that have repeatedly swept down the valleys heading on the edifice Crandell and Mullineaux, ; Crandell, ; Scott and others, Frequency and magnitude estimates for such events can be made by reconstructing the spatial and.

Rock and debris ava- lanches b. For example, the frequency with which lahars have affected areas more than 20 km from the volcano in the past Table 2. An event of this magnitude would be expected to occur an average of once every 1, years. Similarly, lahars that extend to distances of 50 km or more from the volcano have an estimated annual probability of about 0.

An event of this magnitude would be expected to occur an average of once every 10, years. These larger lahars could affect the Puget Lowland, inundating tens to hundreds of square kilometers in relatively densely populated areas.

These probabilities should be considered as minimum estimates, because they are based on incomplete mapping of lahar distributions. As additional lahars are identified through field investigations, these probabilities could be revised upward.

That is, these events could be seen as occurring with greater frequency than present estimates would suggest. The most voluminous debris avalanches and lahars at Mount Rainier originated from parts of the volcano that contained large volumes of hydrothermally altered materials Crandell, ; Scott and others, Frank concluded that the upper west flank and the summit.

Figure 2. Consequently, rivers heading on the west and northwest sides of the volcano are particularly vulnerable to large debris avalanches and lahars. These include the Puyallup and Carbon rivers, which drain into Puget Sound through the densely populated Seattle-Tacoma metropolitan area Figure 2. Debris avalanches of large volume are most likely to occur during eruptions, but they could also occur during dormant periods Crandell, ; Frank, ; Scott and others, All the major rivers that drain Mount Rainier, except the Puyallup-Carbon system, are dammed at distances of 40 to 80 km downvalley from the summit Figure 2.

If reservoirs were empty or nearly so, these dams could probably contain all but the very largest expectable lahars and floods. However, if the reservoirs were full or nearly so, lahars could cause overtopping of the dams and significant downstream flooding. Damage to property and loss of life from debris flows could be substantial.

Geologic mapping of surficial deposits in Mount Rainier National Park by Crandell , and later investigations by Scott and others , have shown that numerous debris flows have entered the Puyallup, Nisqually, and White rivers in the past several thousand years.

The largest debris flow from Mount Rainier, the Osceola Mudflow, occurred about 4, to 5, years ago Scott and others, ; see Table 2. This mudflow traveled down the White River drainage system a distance of approximately km, transported at least 3 km 3 of rock debris Scott and others, , and buried parts of the Puget Lowland that are now heavily populated see Figures 2.

For comparison, the devastating debris flows of the eruption of Nevado del Ruiz that killed 25, people had a volume of 0. Recent excavations in this mudflow for construction in the town of Orting, about 50 km from the volcanic edifice, uncovered 2-m diameter Douglas fir stumps. The curved area of cliffs in the foreground rings Sunset Amphitheater, the source area for the Electron Mudflow.

The central point at the summit is Columbia Crest, formed 2, to 2, years ago. Photos courtesy of David Frank, U. Environmental Protection Agency. After Swanson and others with data from Crandell In the past 45 years, several dozen debris flows and outburst floods have occurred at Mount Rainier, the majority in the Tahoma Creek-Nisqually River drainage Table 2.

These flows did not directly threaten communities, but they did affect areas frequented by visitors to the National Park and required the expenditure of Park Service funds for cleanup and reconstruction.

One popular road remains closed. The largest debris flow extended about 16 km from its origin on the volcanic edifice Crandell, Debris flows of this magnitude are essentially unpredictable at current levels of understanding, but they serve as a reminder of the dynamic landscape surrounding Mount Rainier. Events such as edifice failures, glacier outburst floods, and debris flows can occur in the absence of volcanic eruptions.

Mount Rainier is the high- est volcano in the Cascade Range 4, m above sea level, with approximately 3, m of relief and contains about km 3 Sherrod and Smith, of structurally weak, locally altered rock capped by about 4.

The volcano is inherently unstable Figure 2. If a large lahar were generated in the upper Puyallup River valley without the precursors that typically herald volcanic unrest and eruption, it could arrive at the City of Orting as little as 40 minutes after the initial warning is sounded. Time could be short, and successful mitigation will depend on effective notification of people at risk, public understanding of the hazard, and prompt response by citizens.

This system for automatic detection and notification of a lahar reduces-but does not eliminate-risk in the lahar pathways. Volcanoes often show signs of unrest, such as increased seismicity earthquakes and emission of volcanic gases and swelling of the volcano, days to months in advance of an eruption.

When unrest is detected, scientists will notify emergency-management officials and increase monitoring efforts. The plan describes the responsibilities of agencies and how they will communicate with each other and the public during a volcanic crisis. Know the signs of debris flows and lahars. Experience from around the world shows that moving to high ground off the valley floor is the only way to ensure safety during a lahar. When hiking in valleys on the slopes of Mount Rainier during late summer or during intense rainfall, be alert for the signs of an approaching debris flow-ground shaking and roaring sound-and move up the valley wall to higher ground.

The same is true for lahars, but, because they affect much larger areas, people need to move out of threatened areas before lahars get close. Lahars are almost always preceded by volcanic unrest, so in most instances there will be time to warn people when there is an increased risk. Driedger and William E. Mount Rainier Mount Rainier: The flat floor of the Puyallup River valley near Orting, Washington, is formed by deposits of the year-old Electron lahar, which surged down from Mount Rainier in background.

Majestic Mount Rainier soars almost 3 miles 14, feet above sea level and looms over the expanding suburbs of Seattle and Tacoma, Washington. Each year almost two million visitors come to Mount Rainier National Park to admire the volcano and its glaciers , alpine meadows, and forested ridges.

However, the volcano's beauty is deceptive. It has been the source of countless eruptions and volcanic mudflows lahars that have surged down valleys on its flanks and buried broad areas now densely populated. To help people live more safely with the volcano, USGS scientists are working closely with local communities, emergency managers, and the National Park Service. Lahar at Nevado del Ruiz Armero, Colombia, was battered in by lahars generated by an eruption of glacier-clad Nevado del Ruiz volcano.

Mount Rainier Lahar and Flows Map Mount Rainier hazard zones: This map shows areas that could be affected by debris flows, lahars, lava flows, and pyroclastic flows from Mount Rainier if events similar in size to past events occurred today.

How to prepare for a lahar or other volcano hazard: Learn: Determine whether you live, work, or go to school in a lahar hazard zone. Learn about all volcanic processes that could affect your community. Plan: Develop an emergency plan with your family so that you are prepared for natural hazards and emergencies.

Inquire: Ask public officials to advise you about how to respond during any emergency. Osceola Mudflow Lahar Deposit Studying old lahar deposits: Geologists study the deposits of past lahars to assess potential future hazards. Spatter Cones Mount St. Find Other Topics on Geology. Maps Volcanoes World Maps. Facts About Mount Rainier. Where Are the Canary Islands? Spatter Cones. Mount St. Helens - 30 Years. Largest Volcano.

Yellowstone Supervolcano. Info Alerts Maps Calendar Reserve. Alerts In Effect Dismiss. Dismiss View all alerts. Mount Rainier as seen from the crater rim of Mount St. Helens, overlooking Spirit Lake. USGS Photo. Volcanic Features. Geologic Formations. Volcano evacuation route sign. Tags: volcano volcano monitoring. Stay Connected. Seismicity Seismicity is the study of earthquakes. Volcanic Features Mount Rainier is a volcano and many volcanic features can be found in the park.