Can volcanic eruptions endanger helicopters and other aircraft?

Yes. Encounters between aircraft and clouds of volcanic ash are a serious concern. Jet engines and other aircraft components are vulnerable to damage by fine, abrasive volcanic ash, which can drift in dangerous concentrations hundreds of miles downwind from an erupting volcano.

In the past, many aircraft have accidentally encountered volcanic ash clouds, and in some cases jet engines have temporarily lost power. An international consortium of government agencies (including the USGS, the Federal Aviation Administration, and the National Weather Service), now monitors ash-producing volcanoes and tracks volcanic ash clouds to reduce the likelihood of future encounters.

Learn more: Airborne Volcanic Ash; A Global Threat to Aviation

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Which volcanic eruptions were the deadliest?

Deadliest Volcanic Eruptions Since 1500 A.D. Eruption Year Casualties Major Cause Nevado del Ruiz, Colombia 1985 25,000 1,3 Mudflows 3 Mont Pelée, Martinique 1902 30,000 1 (29,025) 2 Pyroclastic flows 2 Krakatau, Indonesia 1883 36,000 1 (36,417) 2 Tsunami 2 Tambora, Indonesia 1815 92,000 1,2 Starvation 2 Unzendake, Japan 1792 15,000 1 (14,030) 2...

How far would ash travel if Yellowstone had a large explosive eruption?

Knowledge about past eruptions of Yellowstone combined with mathematical models of volcanic ash dispersion help scientists determine where and how much ashfall will occur in possible future eruptions. During the three caldera-forming eruptions that occurred between 2.1 million and 640,000 years ago, tiny particles of volcanic ash covered much of...

Does ash ever erupt from Kīlauea Volcano??

Kīlauea Volcano is renowned for its relatively benign eruptions of fluid lava flows. Therefore, many people were surprised by the small explosions that occurred in Halema`uma`u Crater in 2008 and 2018, and even more surprised to learn that volcanic ash was being erupted from a new gas vent. However, ash emissions from Halema`uma`u Crater are part...

What is "vog"? How is it related to sulfur dioxide (SO2) emissions?

Vog (volcanic smog) is a visible haze comprised of gas and an aerosol of tiny particles and acidic droplets created when sulfur dioxide (SO2) and other gases emitted from a volcano chemically interact with sunlight and atmospheric oxygen, moisture, and dust. Volcanic gas emissions can pose environmental and health risks to nearby communities. Vog...

How much ash was there from the May 18, 1980 eruption of Mount St. Helens?

During the 9 hours of vigorous eruptive activity on May 18, 1980, about 540 million tons of ash from Mount St. Helens fell over an area of more than 22,000 square miles (57,000 square kilometers). The total volume of the ash before its compaction by rainfall was about 0.3 cubic mile (1.3 cubic kilometers), equivalent to an area the size of a...

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 19, 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, or >1,500 °F ), 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...

Can lakes near volcanoes become acidic enough to be dangerous to people and animals?

Yes. Crater lakes atop volcanoes are typically the most acid, with pH values as low as 0.1 (very strong acid). Normal lake waters, in contrast, have relatively neutral pH values near 7.0. The crater lake at El Chichon volcano in Mexico had a pH of 0.5 in 1983 and Mount Pinatubo's crater lake had a pH of 1.9 in 1992. The acid waters of these lakes...

What was the largest volcanic eruption in the 20th century?

The world's largest eruption of the 20th century occurred in 1912 at Novarupta on the Alaska Peninsula. An estimated 15 cubic kilometers of magma was explosively erupted during 60 hours beginning on June 6th. This volume is equivalent to 230 years of eruption at Kilauea (Hawaii) or about 30 times the volume erupted by Mount St. Helens (Washington...

Do volcanoes affect weather?

Yes, volcanoes can affect weather and the Earth's climate . Following the 1991 eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that...

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: 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: April 25, 2016

Citizen Science – Volcanic Ash Collection Workshop and Public Lecture

Two public events are scheduled next week in the City of Kodiak, Alaska about monitoring old volcanic ash resuspended by high winds. Scientists invite the local community to learn more about the potential impacts of resuspended volcanic ash and how to assist in volcano hazards research by collecting samples of the redistributed volcanic ash and dust.

Date published: September 3, 2015

Media Advisory: Remobilized 100-Year-Old Volcanic Ash: Is It a Health Hazard?

Two community events about monitoring old volcanic ash resuspended by high winds are scheduled next week in the City of Kodiak and in Larsen Bay, Alaska.

Attribution: Region 11: Alaska
Date published: August 26, 2014

Volcano Watch — Do Hawaiian eruptions pose a threat to aircraft?

As we work to increase monitoring capabilities on our restless neighbor Mauna Loa Volcano, our colleagues at the The threat posed by ash injected into the atmosphere by explosive eruptions is so well known that seven centers have been established to monitor it worldwide.

Date published: July 1, 2013

New Tool for Reporting Alaska Volcanic Ash Fall Allows Residents to Assist Scientific Monitoring

Wilderness pilots, hikers, boaters and people in Alaskan communities can now report online to authorities if they witness falling ash or an ash cloud from an erupting volcano. The  Alaska Volcano Observatory has developed a new online tool for reporting visible volcanic ash. 

Attribution: Region 11: Alaska
Date published: May 31, 2006

Emergency Drill to Focus on Volcanic Ash

The U.S. Geological Survey (USGS) is among more than 40 local, state, and federal agencies within Clark County, Washington that will be participating in a coordinated practice drill on May 31, 2006, to test their abilities to respond to and recover from a disaster.

Date published: August 23, 1995


Volcanic ash clouds can threaten the lives and safety of airline pilots and passengers. In the past 15 years, more than 80 jet aircraft have been damaged by drifting clouds of volcanic ash, and more than 1,500 people put at risk when engines failed temporarily on 7 airliners. 

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Map of Aleutian Island chain with locations of volcanoes and commercial air traffic routes indicated
March 3, 2017

Air traffic over active volcanoes in the Aleutians

North Pacific and Russian Far East air routes (gray lines) pass over or near more than a hundred potentially active volcanoes (red triangles). Aircraft flying along these routes, some of the busiest in the world, carry more than 50,000 passengers and millions of dollars of cargo each day to and from Asia, North America, and Europe. In the North Pacific region, several

Image shows gray ash covering cars and a house
July 18, 2016

Ash Coating from Rabaul Volcanic Eruption

Ash buries cars and buildings after the 1984 eruption of Rabaul, Papua New Guinea. Credit: USGS

aerial view of airplane hangers collapsed under the weight of wet volcanic ash.
June 13, 2016

Damage to Clark Air Force Base hangers from Pinatubo eruption

Damage to Clark Air Force Base airplane hangers collapsed under the weight of wet volcanic ash from the eruption of Mount Pinatubo in 1991.

May 26, 2016

Forecasting Ashfall Impacts from a Yellowstone Supereruption

  • Yellowstone is one of a few dozen volcanoes on earth capable of "supereruptions" that expel more than 1,000 cubic km of ash and debris.
  • The plumes from such eruptions can rise 30 to 50 km into the atmosphere, three to five times as high as most jets fly.
  • Yellowstone has produced three supereruptions in the past 2.1 million years. The most recent was
Attribution: Yellowstone
Lassen Peak Eruption
April 18, 2016

Lassen Peak Eruption

Satellite image of eruption cloud from Pavlof Volcano in November 2014
November 15, 2014

Satellite image of eruption cloud from Pavlof Volcano in November 2014

Satellite image from the USGS/NASA Landsat-8 satellite showing the eruption cloud at Pavlof Volcano on November 15 at 12:46 pm AKST (21:46 UTC). This is just a portion of the eruption cloud, which extended for more than 250 miles to the northwest at the time this image was collected. In this image, the distance from the erupting vent to the upper left corner of the image

video thumbnail: Volcano Hazards
July 30, 2012

Volcano Hazards

The United States has 169 active volcanoes. More than half of them could erupt explosively, sending ash up to 20,000 or 30,000 feet where commercial air traffic flies. USGS scientists are working to improve our understanding of volcano hazards to help protect communities and reduce the risks.

Video Sections:

  • Volcanoes: Monitoring Volcanoes
May 9, 2012

Volcano Web Shorts 4 - Instruments

USGS technologist Rick LaHusen describes how the development and deployment of instruments plays a crucial role in mitigating volcanic hazards.

May 9, 2012

Volcano Web Shorts 5 - Volcanic Ash Impacts

Volcanic ash is geographically the most widespread of all volcanic hazards. USGS geologist Larry Mastin describes how volcanic ash can disrupt lives many thousands of miles from an erupting volcano. The development of ash cloud models and ash cloud disruption to air traffic is highlighted.

Image: Eyjafjallajökull Eruption
April 17, 2010

Eyjafjallajökull Eruption

Photograph of the eruption from the summit of Eyjafjallajökull from the north looking to the south across the Gígjökull outlet glacier, its "missing" proglacial (ice-margin) lake caused by the jökulhlaup that filled in the lake. 


November 17, 2009

Public Lecture Sneak Peek: Geohazards of the Aleutian Islands -- Great Earthquakes, Great Waves, and Great Volcanic Explosions!

To increase to increase public awareness during Native American Indian National Heritage Month, we will be discussing the anthropology of indigenous peoples in the Aleutian Islands and how continued scientific research can help future forecasting of mega-earthquake and transoceanic tsunami probabilities.