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Here Are The Most Threatening Volcanoes In The United States: Should We Be Worried?

Mar 24, 2020

Image: Kilaeua volcano fissure 8 - USGS/Public Domain
There are currently 169 active volcanoes in the United States according to With Mount Kilauea in Hawaii currently erupting, we’re reminded how powerful and destructive volcanoes truly are.
Volcanoes are a natural phenomenon that we have no control over. All we can do is try to get out of their way. But how many are an actual threat? From a string of volcanoes in the Cascade Mountain Range to a supervolcano beneath the grounds of Yellowstone National Park, these are the most active and threatening volcanoes in the United States.
Mount Rainer Volcano, Washington
The real fear behind the potential eruption of Mount Rainer is that it’s covered with more snow and ice than all of the other volcanoes in the Cascade Range combined. This means that it would lead to an unstoppable amount of lahars or volcanic mudflows.
In past eruptions, Rainer’s lahars have made it all the way to the Puget Sound which is more than 62 miles away. Currently, that is a very developed area, which would be right in the direction of the lahars. Rainer is known to have activity every 500 to 1,000 years with its last eruption being over 500 years ago. Luckily, it appears the volcano isn’t showing any signs of movement.
Mount Baker Volcano, Washington
After Mount Rainer, Mount Baker is the most glaciated mountain in the Cascades. Studies show that Baker seems to be less explosive and active than other peaks in the Cascades although it had a few minor eruptions in the 1800s.
However, because of the vast amounts of ice at the top, it doesn’t need a full-scale eruption to cause devastating lahars to rush down the mountainside. In 1975, there was fear of an eruption after an increase in heat flow and volcanic gases. Thankfully, it never happened. Although there doesn’t appear to be any imminent flow of magma, Mount Baker is still on watch.
Mount Mazama/Crater Lake Volcano, Oregon
Around 7,000 years ago, Mount Mazama, a stratovolcano collapsed to create what we know as Crater Lake. The caldera was six miles wide and was one of the most massive eruptions of the last 10,000 years. Eventually, the water caldera cooled which formed the lake.
No rivers or streams are coming in or out from the lake, and its only source of water is rain and snowmelt. With evaporation and added water, it is estimated that the water is completely replaced every 250 years. However, hydrothermal activity has shown signs on the lake’s floor that eventually Mount Mazama will most likely erupt again.
Hawaii has more than Mount Kilauea to worry about.
Mauna Loa Volcano, Hawaii
Although the most recent eruption of Hawaii’s Kilauea volcano has been devastating enough, there’s another volcano in Hawaii that has proven to be far more dangerous. The Mauna Loa Volcano is the largest volcano on earth and has erupted 33 times since it was first documented in 1843. Although it has been relatively dormant since 1984, it is still a looming threat.
The reason for its constant activity is because the Pacific crust in that area has been sinking below the continent. This contact with water causes melting and therefore creates volcanoes. The location of the volcano has made it part of the Decade Program, which promotes research of the world’s most dangerous volcanoes on earth.
Lassen Volcanic Center, California
Although Lassen Peak is an unpredictable volcano in Northern California, it is one of a string of volcanoes known as the Lassen Volcanic Center. All of these volcanoes are considered to be relatively dangerous and active.
The next eruption might not occur specifically on Lassen Peak but could be on a neighboring volcano, or a new one entirely. Lassen’s last eruption occurred between 1915 and 1917 and was similar to the Mount St. Helen’s eruption but on a smaller scale. The entire Lassen Volcanic Center has been under surveillance to record and predict any future eruptions in the area.
Redoubt Volcano, Alaska
Mount Redoubt or the Redoubt Volcano is an active stratovolcano on the Aleutian Range in Alaska. It is at the head of the Chigmit Mountains subrange in Lake Clark National Park and Preserve. It is the highest summit of the Aleutian Range at 10,197 feet in elevation.
Although it has been active for more than 1,000 years, it has erupted four times since it was first seen: 1902, 1966, 1989, and 2009. The eruption of 1989 was also the first eruption that was successfully predicted by long-period seismic events. Currently, the Alaska Volcano Observatory has rated Redbout at Aviation Alert Level Green and Volcano Alert level as normal. However, that does not put an eruption out of the question.
See why scientists are starting to take the Yellowstone supervolcano seriously.
Yellowstone Caldera, Wyoming
Beneath Yellowstone National park is a supervolcano with the potential to shoot upwards of 250 cubic miles of magma, ash, dust, and rocks into the sky in one eruption. Although an explosion of this magnitude hasn’t happened in over 600,000 years, the volcano is still considered to be active.
It has been noted that an eruption of this size would have potentially worldwide ramifications and would permanently change the geographics of the surrounding locations. However, scientists claim that it’s unlikely we will see an eruption like that in 1,000 or even 10,000 years. To be safe, NASA has even started considering strategies on how to defuse the supervolcano if it ever started showing clear signs of danger.
Any of the “Three Sisters” in Oregon could erupt next.
Three Sisters Volcanoes, Oregon
The South Sister Volcano is part of the Three Sisters volcanic hotbed that spans over 115 square miles west of Bend, Oregon. Although the South Sister has been labeled as a “very high threat” by the United States Geological Survey, it has been noted that next eruption could come from any one of the Three Sisters.
In the late 1990s and early 2000s, something now known as “the Buldge” began to develop between the Middle and South Sister. It was believed that this deformation was a collection of magma underground which could have led to an eruption. Although “the Bulge” has since decreased, it doesn’t mean that it won’t result in an eruption in the future.
Mount Augustine Volcano, Alaska
The Augustine Volcano forms Augustine Island in the Kenai Penninsula Borough of southcentral coastal Alaska. The island has an area of 32.4 square miles and is primarily made up of post-eruption deposits. The island is inhabited with a summit altitude of 4,134 feet. The summit also consists of overlapping lava dome complexes that have been formed over time in both prehistoric and modern eruptions.
In recent years, the volcano erupted on numerous occasions, with the largest being in 1986 when ash deposits reached Anchorage around 174 miles away. Because the island is uninhabited and relatively distant from most developed areas scientists keep an eye on it but without much worry.
Mount Shasta in Northern California is considered to be a “very high threat”.
Mount Shasta Volcano, California
Another volcano in California classified as “very high threat” by the United States Geological Survey is Mount Shasta. This volcano is concerning because there are densely populated communities at the base and on the face of the mountain.
The last reported eruption from the mountain was seen all the way from the Pacific Ocean in 1786. However, it is assumed that the explosion wasn’t all that disastrous. Although we haven’t seen an eruption from it for hundreds of years, it is still considered to be an active volcano that requires constant observation for fear of something happening in the future.
Long Valley Caldera, California
The Long Valley Caldera is a depression in the earth in eastern California. Located adjacent to Mammoth Mountain, it measures around 20 miles long, 11 miles wide, and 3,000 feet deep.
The caldera was formed after the eruption of a supervolcano over 760,000 years ago. This left a giant depression in the earth which now includes thermal springs and gas emissions which have been killing the trees and wildlife in the area. Over the last few decades, there has been various activity such as earthquakes, uplift in the dome, and changes in thermal spring and gas emissions. This has risen concern among scientists about a possible eruption in the future.
Mount Hood Volcano, Oregon
Located in Oregon, Mount Hood was very active during the end of the last Ice Age, with two significant eruptions over the course of the last 1,500 years. The last one is believed to have occurred not long before the Lewis and Clark expedition West.
Research has shown that the mountain may have recently stopped being dormant, meaning that there should be an expected eruption every few centuries starting soon. What’s threatening about volcanic activity on Mount Hood is that numerous highways and communities are right in the wake of any major eruption.
Glacier Peak, Washington
Glacier Peak is one of the most active volcanoes in the Cascades. However, it is the most remote of the active volcanoes in the region. Glacier Peak and Mount St. Helens are the only two volcanoes in Washington that have seen massive explosions over the last 15,000 years.
This is because their eruptions explode outward rather than flow generally from the top vent. Also, because it is covered in snow, eruptions lead to large lahar flows which cause extensive damage to the mountain. Its last explosion was 300 years ago, and the USGC believes we may not end up seeing another eruption from it in our lifetime. Nevertheless, it is monitored on a regular basis just in case.
Mount Akutan Volcano, Alaska
Mount Akutan is a stratovolcano located in the Aleutian Islands of Alaska. The mountain has 1.3-mile caldera that was formed after a significant eruption around 1,600 years ago. Over the years, there have been minor eruptions with a lava flow in 1978 reaching within a mile of the coast.
The most recent volcanic activity was back in 1992, yet there is still activity at the base of the Lava Point. Moreover, an earthquake swarm in 1996 led to some changes on the mountain and had people preparing for another eruption. Many people evacuated the island, yet nothing major ended up happening.
Mount Makushin Volcano, Alaska
Mount Makushin is an ice-covered volcano located on Unalaska Island in the Aleutian Islands of Alaska. Its summit is the highest point of the island at 6,680 feet in elevation. Out of all of the 52 active volcanoes in the state of Alaska, it is considered to be the most active.
Over the past several thousand years, it has erupted 24 times. It’s most recent activity was in 1995. Although these eruptions were small to moderate, for the most part, people are still concerned about the possibility of a bigger eruption in the future. This would be particularly dangerous because it is situated on an island.
Mount Cleveland is constantly erupting in Alaska. Check out how many times in the last few decades!
Mount Cleveland Volcano, Alaska
Mount Cleveland is an almost symmetrical volcano on Chuginadak Island in Alaska. It has an elevation of 5,675 feet and is one of the most active out of the 75 volcanoes in the Aleutian Arc. In the last 230 years, it has erupted over 22 times, causing one death in 1944.
In fact, it’s so active that it erupted three times in 2009, twice in 2010, and once in 2011, 2017 and 2018. Monitoring the volcano has proven difficult because of its remoteness and the Alaska Volcano Observatory relies on satellite images to watch its activity.
Mount Newberry Volcano, Oregon
The Newberry Volcano or Newberry Caldera is an active shield-shaped volcano located 35 miles east of the Cascade Range. Roughly the size of Rhode Island, it is the largest volcano in the Cascade Volcanic Arc with a total column of around 120 cubic miles. Within the caldera, there are two large lakes which have more than 400 vents, the most of any volcano in the United States.
Although it is a popular destination for fishing, hiking, boating, and camping, it still poses a threat. It is not far from a few populated areas and is expected to eventually erupt causing lava flows, lahars, floods, avalanches, and more. It is currently being monitored by the United States Geographical Survey.
Mount Spurr Volcano, Alaska
Located in Alaska, Mount Spurr is the highest volcano in the Aleutian Arc. It has a large lava dome at the top which is open to the south. In 2004, there was a heating event which melted the snow on top and created a lake, but by 2008, it began to fill with snow after significant cooling.
Although the volcano is currently at a Level of Concern Color Green Code, in 2004, it was raised to a yellow after an increasing amount of earthquakes. These earthquakes could have been the result of moving magma beneath the mountain, but nothing more came of it. At the moment, the biggest concern of an eruption would be disrupting air travel.
Mount St. Helens Volcano, Washington
On May 18, 1980, Mount St. Helens in Washington erupted, marking the most destructive volcanic eruption in United States history. It killed 57 people, blasting 520 million tons of volcanic ash into the air covering the sky for hundreds of miles in every direction.
The volcano has erupted more than any other volcano in the Cascade Range within the last 10,000 years and continues to do so on a smaller scale more recently. It is unlikely that there will be an explosion even close to the one in 1980 because the mountain is gone from the 1980 blast. However, that doesn’t mean that a new explosive cycle isn’t out of the question.
Mount Adams Volcano, Washington
Mount Adams is an active volcano in the Cascade Range of Washington. Although the mountain hasn’t erupted in over 1,000 years, it is still considered to be active. It is the biggest volcano in Washington and is the second largest in the Cascades.
The volcanic field which the mountain is established on has been active for over one million years with the most activity happening around 520,000 years ago. Although the volcano is also located more eastern than some others in the Cascades, it still hasn’t been written off as a potential threat.


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