How dangerous is Mount Rainier?

Although Mount Rainier has not produced a significant eruption in the past 500 years, it is potentially the most dangerous volcano in the Cascade Range because of its great height, frequent earthquakes, active hydrothermal system, and extensive glacier mantle.

Mount Rainier has 26 glaciers containing more than five times as much snow and ice as all the other Cascade volcanoes combined. If only a small part of this ice were melted by volcanic activity, it would yield enough water to trigger enormous lahars (debris flows and mudflows that originate on a volcano). Mount Rainier's potential for generating destructive mudflows is enhanced by its great height above surrounding valleys.

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How would an eruption of Mount Rainier compare to the 1980 eruption of Mount St. Helens?

Eruptions of Mount Rainier usually produce much less volcanic ash than do eruptions at Mount St. Helens. However, owing to the volcano's great height and widespread cover of snow and glacier ice, eruption-triggered debris flows ( lahars ) at Mount Rainier are likely to be much larger -- and will travel a greater distance -- than those at Mount St...

What is the greatest hazard presented by Mount Rainier?

Debris flows ( lahars ) pose the greatest hazard to people near Mount Rainier . A debris flow is a mixture of mud and rock debris that looks and behaves like flowing concrete. Giant debris flows sometimes develop when large masses of weak, water-saturated rock slide from the volcano's flanks. Many of these debris flows cannot be predicted and may...

How many eruptions have there been in the Cascades during the last 4,000 years?

Eruptions in the Cascades have occurred at an average rate of one to two per century during the last 4,000 years. Future eruptions are certain. Learn more: Eruptions in the Cascade Range During the Past 4,000 Years USGS Cascades Volcano Observatory

How far did the ash from Mount St. Helens travel?

The May 18, 1980 eruptive column at Mount St. Helens fluctuated in height through the day, but the eruption subsided by late afternoon. By early May 19th, the eruption had stopped. By that time the ash cloud had spread to the central United States. Two days later, even though the ash cloud had become more diffuse, fine ash was detected by systems...

How dangerous are pyroclastic flows?

A pyroclastic flow is a hot (typically >800 °C), chaotic mixture of rock fragments, gas, and ash that travels rapidly (tens of meters per second) away from a volcanic vent or collapsing flow front. Pyroclastic flows can be extremely destructive and deadly because of their high temperature and mobility. For example, during the 1902 eruption of...

Do earthquakes large enough to collapse buildings and roads accompany volcanic eruptions?

Not usually. Earthquakes associated with eruptions rarely exceed magnitude 5, and these moderate earthquakes are not big enough to destroy buildings and roads. The largest earthquakes at Mount St. Helens in 1980 were magnitude 5, large enough to sway trees and damage buildings, but not destroy them. During the huge eruption of Mount Pinatubo in...

Why is it important to monitor volcanoes?

The United States and its territories contain 169 geologically active volcanoes, of which 54 volcanoes are a high threat or very high threat to public safety. Many of these volcanoes have erupted in the recent past and will erupt again in the foreseeable future. As populations increase, areas near volcanoes are being developed and aviation routes...

How can we tell when a volcano will erupt?

Most volcanoes provide warnings before an eruption. Magmatic eruptions involve the rise of magma toward the surface, which normally generates detectable earthquakes. It can also deform the ground surface and cause anomalous heat flow or changes in the temperature and chemistry of the groundwater and spring waters. Steam-blast eruptions, however,...

What are some benefits of volcanic eruptions?

Over geologic time, volcanic eruptions and related processes have directly and indirectly benefited mankind. Volcanic materials ultimately break down and weather to form some of the most fertile soils on Earth, cultivation of which has produced abundant food and fostered civilizations. The internal heat associated with young volcanic systems has...

Can an eruption at one volcano trigger an eruption at another nearby volcano?

There are a few historic examples of simultaneous eruptions from volcanoes or vents located within about 10 km of each other, but it's very difficult to determine whether one eruption caused the other. To the extent that these erupting volcanoes or vents have common or overlapping magma reservoirs and hydrothermal systems, magma rising to erupt...

How Do Volcanoes Erupt?

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic...
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Date published: December 19, 2018

Which U.S. volcanoes pose a threat?

USGS Volcanic Threat Assessment updates the 2005 rankings.

Date published: May 16, 2017

EarthWord–Lahar

Which sounds more dangerous, lava or mud? The answer may surprise you...

Date published: May 1, 2017

May is Volcano Preparedness Month in Washington State

May is Volcano Preparedness Month in Washington, providing residents an opportunity to become more familiar with volcano hazards in their communities and learn about steps they can take to reduce potential impacts.

Date published: September 12, 2016

EarthWord–Subduction

It’s not flirting for submarines, but this week’s EarthWord does feature the ocean...

Date published: August 22, 2016

EarthWord–Tephra

Look! In the sky! It’s a bird, it’s a plane! Wait, run, it’s this week’s EarthWord!

Filter Total Items: 15
February 22, 2018

PubTalk 2/2018 — USGS Cascades Volcano Observatory

Title: The USGS Cascades Volcano Observatory - Research, monitoring, and the science of preparing society for low-probability, high-consequence events

  • Volcanoes in the Cascade Range erupt twice per century on average, with eruptions often lasting for years.
  • Although eruptions are generally not as high-consequence as large earthquakes, they are still
...
Attribution: Natural Hazards
Damage from Nevado del Ruiz Lahar
November 9, 2016

Damage from Nevado del Ruiz Lahar

In November 1985, a lahar (volcanic mudflow) originating from Nevado del Ruiz volcano inundated the town of Armero, destroying all infrastructure in its path and killing 23,000 people. VDAP was developed in response to this tragedy. Photograph credit: USGS/VDAP

 Mt. Rainier Lahar Hazard Map
November 9, 2016

Mt. Rainier Lahar Hazard Map

Volcano hazard map showing the extent of lahar hazards in towns and valleys surrounding Mt. Rainier in Washington. Image credit: USGS

Photograph of Mount Rainier and Orting, Washington
April 11, 2016

Photograph of Mount Rainier and Orting, Washington

Photograph of Mount Rainier and Orting, Washington, as seen from a ridge to the west. Orting is one of many communities that are in lahar-prone areas below the flanks of Mount Rainier. 

Image: Field Work on Mount Rainier
March 15, 2016

Field Work on Mount Rainier

Researcher Amanda Kissel pauses by a lake in Mt. Rainier National Park.

Image: View of Mount Rainier
August 1, 2015

View of Mount Rainier

A view during the 2015 Climate Boot Camp site visit to discuss landscape response to climate change at Mount Rainier, Washington.

Large snow-covered, cone shaped mountain in background, looming over suburban area in foreground
January 18, 2014

Mount Rainier Looms over the Puyallup Valley, Washington

Mount Rainier volcano looms over Puyallup Valley, near Orting, Washington.

May 9, 2012

Volcano Web Shorts 6: Societal Impacts of Volcanism

USGS geologist, Angie Diefenbach, describes how she uses GIS, (Geographic Information Systems) software to study volcanic eruptions and their impacts on society.

May 9, 2012

Volcano Web Shorts 2: Debris Flows

Debris flows are hazardous flows of rock, sediment and water that surge down mountain slopes and into adjacent valleys. Hydrologist Richard Iverson describes the nature of debris-flow research and explains how debris flow experiments are conducted at the USGS Debris Flow Flume, west of Eugene, Oregon. Spectacular debris flow footage, recorded by Franck Lavigne of the

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USGS
March 19, 2008

What is the greatest hazard presented by Mount Rainier?

Listen to hear the answer.

Image shows damage from a lahar from Pinatubo's 1991 eruption
November 30, 2000

Pinatubo Lahar Damage

Lahar devastation after the eruption of Mount Pinatubo, Philippines.