The Twenty Most Dangerous Volcanoes in the United States

The United States is home to 161 active volcanoes, any of which could erupt at any time.

Here will enumerate for you the twenty most dangerous volcanoes in the United States of America:

The most dangerous volcanoes: when a volcano on New Zealand’s Isle of Wight erupted on December 9, 2019, 17 people were killed. Dozens of people are still in hospitals receiving treatment for burns sustained when steam and molten rock erupted from the volcano. Could the same thing happen in the United States?

There are currently 161 active volcanoes in the United States, and the USGS keeps tabs on them in the National Volcanic Threat Assessment. So the danger posed by a volcano depends on its location and volcanic style, and the list evaluates the volcanoes that require the greatest effort to mitigate the risks.

There are at least more than 20 active volcanoes in the United States that must be monitored.

1. Ilia Mina Volcano, Alaska

Alaska volcano
Source: NPS

US Geological Survey Threat Score: 115, Aviation Threat: 34

Located 134 miles (215 km) southwest of Anchorage, Alaska, Mount Ilia Mina is a 1,016-foot (3,053 m) volcano capped by glaciers in the Aleutian Range. Also known to have erupted in 5050 BC, 2050 BC, 450 BC, and in 1650 AD, 1867 AD, and 1876 AD. Moreover, Mount Elia Mina produces an almost constant plume of steam and sulfur gases, and seismic swarms were detected on the mountain in 1996–97 and in 2011–13 that’s why it’s one of the most dangerous volcanoes.

2. Mount Okmok – Alaska

Source: USGS

US Geological Survey Threat Score: 117, Aviation Threat: 47

In addition, Mount Okmok is located on Amnak Island in the East Aleutian Islands. Also, the 9.3-kilometer-wide circular crater, or caldera, was filled by a 150-meter-deep crater lake. Okmok volcano erupted between 8,300 and 2,400 years ago, and again on July 12, 2008, when it spewed a column of ash 15,000 m into the sky. This eruption lasted for five and a half days and created a cone 800 feet high. Huge volcanic mudflows, or lahars, stretched all the way from the caldera to the seacoast.

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3. Long Valley Caldera – California

Source: BLM/Facebook

USGS Threat Score: 129. Aviation Threat: 29

Located next to Mammoth Mountain, Lung Valley Caldera is one of the largest volcanic lakes on Earth. It is 20 miles (32 km) long from east to west, 18 km from north to south, and 910 m deep.

In May 1980, four magnitude 6 earthquakes struck the southern rim of Long Valley, and the caldera floor rose by 250 mm. Since 1980, there have been seismic swarms, uplifts, changes in thermal springs, and gas emissions. In April 2006, three ski patrollers at Mammoth Mountain Ski Area died from carbon dioxide asphyxiation when they fell into a fumarole, or steam vent, on the mountain.

4. Crater Lake Volcano, Oregon

Crater Lake Oregon
Source: Planet Labs

US Geological Survey threat score: 129; aviation threat: 37

Located in south-central Oregon, 97 km northwest of Klamath Falls, and about 130 km northeast of Medford lies Crater Lake. At 594 meters deep, it is the deepest lake in the United States. The lake was formed after when a massive volcanic eruption of Mount Mazama 7,700 years ago occurred. Also, the volcanic eruption caused 50 cubic kilometers of land to erupt.

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5. Mauna Loa – Hawaii

Source: USGS

US Geological Survey Threat Score: 131, Aviation Threat: 4.

In addition, Mauna Loa is one of the largest active volcanoes on Earth. Covering half of the island of Hawaii, it last erupted in 1984 when lava flowed 7.75 km from Hilo, the island’s largest population center. As well eruptions in 1926 and 1950 destroyed villages and the city of Hilo was built on lava flows from volcanic eruptions in the late 19th century.

Mauna Loa erupted 700,000 years ago, and only emerged above sea level 400,000 years ago. Its magma comes from a hotspot in Hawaii that created the Hawaiian island chain. The movement of the Pacific tectonic plate will move Mauna Loa away from the hotspots between 500,000 and 1 million years from now, and the Mauna Loa volcano will become extinct.

6. Glacier Peak – Washington

Glacier Peak
Source: Walter Siegmund/Wikimedia Commons

US Geological Survey Threat Score: 135, Aviation Threat: 37

Glacier Peak is the fourth-highest peak in the state of Washington and is located in Snohomish County, 110 km northeast of downtown Seattle. The ice cap has erupted five times in the past three thousand years. They erupted in 3550 BC, 3150 BC, 850 BC, 200 AD (lasting over 50 years), 900 AD (±50 years), 1300 AD (300 years), and 1700 AD (±100 years). About 13,000 years ago, it produced a series of eruptions and lava flows that mixed with snow, ice, and water, forming lavas. This filled the North Fork of the Stillaguamish River and the Skagit River.

A 2005 study by the US Geological Survey identified Glacier Peak as one of nine volcanoes that are considered “hazardous volcanoes with insufficient monitoring.”

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7. Mount Baker, Washington

Mount Baker Washington
Source: Lhb1239/Wikimedia Commons

US Geological Survey Threat Score: 139. Aviation Threat: 15.

Mount Baker is located about 30 miles east of Bellingham, Washington, in the northern Cascade Mountains. It is located at an elevation of 3,286 meters and is the second most active thermal crater in the Cascade Range, after Mount St. Helens.

There are hundreds of fumaroles in the mountain’s vent gases, primarily water vapor, carbon dioxide, and hydrogen sulfide. A volcanic eruption 6,600 years ago deposited a layer of ash that extended more than 64 kilometers to the east. In 1891, a lahar area of 15 km³ covered 2.6 km².

In March 1975, the heat coming from the volcano increased tenfold, and authorities closed public access to the Baker Lake Recreation Area.

8. Newberry Volcano, Oregon

Newberry Volcano Oregon
Source: QDM/Wikimedia Commons

US Geological Survey Threat Score: 146, Aviation Threat: 30

Newberry Volcano is located 32 kilometers south of Bend, Oregon, and is a large volcano. It extends 121 km from north to south and 43 km from east to west and has more than 400 vents, the largest of any volcano in the contiguous United States.

The Newberry eruption began 600,000 years ago, and the last eruption occurred 1,300 years ago. Today, the volcano is located 31 km away from 16,400 people and 100 km away from almost 200,000 people, and any eruption with lava flows, landslides, ash, earthquakes, avalanches, and floods poses a great danger to life.

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9. Augustine Volcano – Alaska

Augustine volcano
Source: USGS

US Geological Survey Threat Score: 151, Aviation Threat: 48

Augustine Volcano forms Augustine Island, an 83.9-square-kilometer area located in southwest Cook Inlet on the Kenai Peninsula. Located 280 km southwest of Anchorage, Augustine Volcano is 7.5 miles (12 km) east to west, 10 km north to south, and has an elevation of 1,260 meters.

Augustine erupted in 1883, 1935, 1963–64, 1976, 1986, and 2006. Minor eruptions occurred in 1812, 1885, 1908, 1944, and 1971. On March 27, 1986, an eruption left ash over Anchorage, and air traffic was disrupted. In April 2005, a new eruption began that continued until March 2006, with an explosion occurring on January 11, 2006.

10. Lassen Volcano – California

At the foot of Lassen Peak, Lake Helen
Source: NPS

US Geological Survey Threat Score: 153, Aviation Threat: 32

Lassen Volcano is located at an altitude of 3,187 meters above the North Sacramento Valley. The lava dome has a volume of 2.5 cubic kilometers, making it the largest lava dome on Earth. Lassen has undergone at least one explosive eruption, creating a crater 110 meters deep and 300 meters in diameter.

In May 1914, Lassen became volcanically active after 27,000 years of dormancy. A column of volcanic ash and gas was released at an altitude of more than 9,100 meters, and when the column collapsed in a lava flow, it destroyed 7.8 square kilometers of land and spewed lava that extended 24 km from the volcano.

Both the National Park Service and the US Geological Survey actively monitor Lassen’s fumaroles, hot springs, and mud pools. Recent surveys have shown that Lassen, along with three other chain volcanoes, is experiencing subsidence, with the summit of Lassen volcano sinking 10 mm into the ground each year.

11. Spur Mountain – Alaska

Mount Spurr
Source: USGS

US Geological Survey Threat Score: 160, Aviation Threat: 48

Mount Spur is located 142 km west of Anchorage and is the highest volcano in the Aleutian Arc. It is a caldera 5 km wide and open to the south. The Spur erupted in 1953 and 1992, and in July 2004, the Spur had an increasing number of earthquakes.

In August 2004, a heating event melted snow and ice and created a small crater lake. By 2005, sorties revealed that the water in this lake had dried up. Mount Spur lies along major trans-Pacific aviation routes, and an eruption could significantly disrupt air travel, with jet engines clogged with ash.

12. Makushin Volcano – Alaska

Source: USGS

US Geological Survey Threat Score: 161, Aviation Threat: 47

Makushin is located on the island of Alaska in the Aleutian Range, at 2,036 meters. Caldera is 2.5 km by 3 km. Over the past millennia, Makushin has erupted more than two dozen times, most recently in 1995.

During that eruption, which occurred on January 30, 1995, ash was sent 2.5 km high. The closest towns to Makushin are Alaska and Danish Port, and studies have shown that tapping the geothermal reservoir beneath the volcano could provide electrical power to both towns.

13. Akutan Volcano – Alaska

Mount Akutan
Source: USGS

US Geological Survey Threat Score: 161, Aviation Threat: 47

Akutan Peak in the Aleutian Islands is 1,303 m high, and a 2 km-wide caldera was formed during an eruption that occurred 1,600 years ago. The Alaska Volcano Observatory recorded 33 volcanic eruptions at Akutan, giving it the title of the most explosive volcanic eruption in Alaska.

The volcano last erupted in 1992; however, in March 1996, a swarm of earthquakes was followed by a rise on the western side and a fall on the eastern side of the volcano.

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14. The Three Sisters – Oregon

The three sisters oregon
Source: USGS

US Geological Survey Threat Score: 165, Aviation Threat: 30

The three peaks, known as North Sister, Middle Sister, and South Sister, are each more than 3,000 meters high. Neither the North Sister nor the Middle Sister have erupted in the last 14,000 years and most likely will not erupt again.

However, the South Sister last erupted 2,000 years ago and remains a threat. If the Southern Sister erupts, it would cover the city of Bend, Oregon, 36.5 km away, with ash to a depth of 25 to 51 mm.

The volcano could unleash lava flows and mudflows. During the 2000s, the South Sisters saw a rise of 28 cm, but the Sirba earthquake in 2004 caused the rise to halt.

15. Mount Hood – Oregon

Mount Hood
Source: FHWA

US Geological Survey Threat Score: 178. Aviation Threat: 30.

Mount Hood is located 80 km southeast of Portland, Oregon, at an elevation of 3,426 meters, and according to the USGS, the chances of Mount Hood erupting in the next 30 years are between 3% and 7%. There have been four major volcanic eruptions over the past 15,000 years, with the last three occurring within the past 1,800 years. The last major eruption occurred in 1781–82, and the last minor eruption occurred in August 1907.

In July 1980 and June 2002, there were several earthquake shocks on the mountain, and sulfur gases and hot springs were activated.

16. Mount Shasta – California

Mount Shasta
Source: Ewen Denney/Wikimedia Commons

US Geological Survey Threat Score: 178, Aviation Threat: 39

The mountain is located at an altitude of 4,322 meters and consists of four overlapping dormant volcanic cones. Over the past 4,500 years, Mount Shasta has erupted every 600 years, and deposits from these eruptions can be found in nearby cities.

Mount Shasta’s last eruption is believed to have occurred around 1250 AD, but if the mountain erupts again, the cities of Lake Shasta, Redding, and Anderson, California, along with Ashland, Oregon, would be exposed to volcanic ash and lava flows.

17. Redoubt Volcano – Alaska

Redoubt Volcano
Source: Alaska Volcano Observatory/Wikimedia Commons

US Geological Survey Threat Score: 201, Aviation Threat: 48

Redbut Mountain is located 180 km southwest of Anchorage, at an elevation of 3,108 m. It erupted in 1902, 1966, 1989, and 2009. The 1989 eruption sent volcanic ash reaching 14,000 m and stopped the engines of KLM Flight 867, a Boeing 747, as it flew through the volcanic plume.

Fortunately, the pilots could restart the engines, and the plane landed safely in Anchorage. Ash from that eruption covered an area of 20,000 square kilometers, and lava and volcanic flows reached Cook Inlet, 35 km away.

On March 22, 2009, Mount Redoubt began erupting and continued to erupt for several months. Ash clouds reached a height of 20,000 m, and the cities of Anchorage and Valdez were covered in ash. On March 28, ash forced the closure of Anchorage Airport for more than 12 hours.

Since 2009, there have been small earthquakes, gas vents, and collapses. The mountain emits more than 10,000 metric tons of carbon dioxide and sulfur dioxide daily.

18. Mount Rainier – Washington

Mount Rainier
Source: Stan Shebs/Wikimedia Commons

US Geological Survey threat score: 203; aviation threat: 37

Mount Rainier is located 95 kilometers southeast of Seattle, Washington, at an elevation of 4,392 meters. It is considered one of the most dangerous volcanoes in the world, and due to the large amount of ice on its summit and sides, it can produce huge fires that could threaten 80,000 people living in its vicinity.

Mount Rainier could produce lava flows and mudflows that would devastate the communities of Enumclaw, Orting, Cant, Auburn, Bailope, Sumner, and Renton and could cause tsunamis in both Puget Sound and Lake Washington. Reflecting the danger posed by Mount Rainier, Pierce County, south of Seattle’s King County, installed sirens and posted signs for escape routes.

19. Mount St. Helens – Washington

St. Helen Volcano
Source: Lyn Topinka/Wikimedia Commons

USGS Threat Score: 235; Aviation Threat: 59

St. Helens is located 80 km northeast of Portland, Oregon, and 154 km south of Seattle, Washington. In March 1980, Mount St. Helens experienced an earthquake and a steam vent, and in April 1980, the north side of the mountain began to swell. On May 18, 1980, a 5.1-magnitude earthquake collapsed the mountain’s north face, causing the largest debris avalanche in recorded history.

Magma erupted from the volcano in a lava flow that flattened trees and buildings over an area of more than 600 square kilometers and released more than 1.5 million metric tons of sulfur dioxide into the atmosphere. 57 people were killed, 250 homes were destroyed, 47 bridges, 24 km of railway lines, and 298 km of highway were destroyed. The ash plume reached 27 km in height and moved east at 100 km per hour, reaching Idaho and Edmonton in Alberta, Canada. Lava flowed down the Tuttle and Cowlitz Rivers into the Columbia River.

The volcanic eruption reduced the mountain’s height from 2,950 meters to 2,549 meters and left a 1-mile-wide, 1.6-kilometer horseshoe-shaped crater. Small eruptions continued, and a new lava dome formed. On March 8, 2005, a new eruption sent a column of steam and ash 11,000 meters high into the sky.

20. Kilauea Volcano – Hawaii

Kilauea Fissure
Source: USGS

US Geological Survey threat score: 263, aviation threat: 48

Located on the Big Island of Hawaii, Kilauea did not emerge from the sea until about 100,000 years ago. It was created by the hot spot of the Hawaiian Emperor Mountains and erupted almost continuously from 1983 to 2018. Lava from Kilauea destroyed the towns of Kalapana and Keemu, and in 2018, twenty lava vents erupted in the city of Puna, forcing the evacuation of thousands of people.

On May 17, 2018, the volcano erupted, spewing ash 9,144 meters into the air. Lava destroyed Hawaii’s largest natural freshwater lake, covered most of the Leilaini and Llanipuna parks, and flooded the communities of Kapoho, Hawai’i, and most of the beach areas in Kapoho. Upon reaching the ocean, the lava extended up the coast for about a mile out to sea and formed a lake that is formed when lava mixes with seawater and consists of toxic hydrochloric acid and glass particles.

In all, the lava destroyed 716 homes. On December 5, 2018, the eruption that began in 1983 was officially declared over.  In June 2019, the USGS released a study indicating that Kilauea’s shallow-topped magma chamber was slowly being refilled.

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