Philips ConnorThe most dangerous volcanoes in the US may not be as dangerous as those in other countries, but they do pose significant dangers in several ways. Within the territory of the US is the volcano with the loudest eruption on record.
Others are a lot more subtle; with their activity being only barely observable. This information is curated based on a combination of factors including eruption history, potential impact on populations and infrastructure, aviation threats, and geological activity. This is informed by the U.S. Geological Survey (USGS) National Volcanic Threat Assessment, with additions for geographic diversity and potential hazards.
Most Dangerous Volcanoes In The US
1. Kīlauea (Hawaii)
Kīlauea is one of the world’s most active volcanoes, located on Hawaii’s Big Island. Known for its persistent lava flows and frequent eruptions, it has caused significant property damage and reshaped landscapes, especially during the 2018 eruption. While its eruptions are usually non-explosive, the proximity to populated areas makes it a constant threat. Its volcanic activity also contributes to air quality issues due to volcanic smog, or “vog.”
2. Mount St. Helens (Washington)
Mount St. Helens is infamous for its catastrophic 1980 eruption, which caused 57 deaths and widespread destruction. Located in southwestern Washington, it remains highly active with frequent earthquakes, dome-building eruptions, and glacier-related hazards. Its history of explosive behavior, coupled with proximity to populated areas and infrastructure, makes it a top concern. The landscape around the volcano is still recovering from the massive lateral blast and subsequent lahars.
3. Mount Rainier (Washington)
Mount Rainier is a massive stratovolcano towering over the Seattle-Tacoma region. Though it hasn’t erupted in over a century, it poses a serious threat due to its extensive glacial coverage, which could generate deadly lahars during an eruption. With over 3 million people living in downstream valleys, an eruption or even a major landslide could be catastrophic. Rainier’s steep slopes and seismic activity make it a constant monitoring priority.
4. Redoubt Volcano (Alaska)
Located in the Aleutian Range, Redoubt Volcano is an active stratovolcano best known for its explosive eruptions, particularly in 1989–90 and 2009, which disrupted air traffic with massive ash clouds. Though remote, its ash plumes threaten major flight paths, including those to and from Anchorage. The volcano’s frequent seismicity, glacier-covered flanks, and past lahar events make it one of Alaska’s most hazardous volcanoes despite its isolation.
5. Mount Shasta (California)
Mount Shasta, located in northern California, is a prominent and potentially explosive stratovolcano with a history of pyroclastic flows and lava domes. Last erupting in the 18th century, it threatens nearby communities like Mount Shasta City and Redding. Its symmetrical shape belies its capacity for violent eruptions, and lahars could impact areas far downstream. It’s a vital part of the Cascade Volcanic Arc and is closely monitored by USGS.
6. Mount Hood (Oregon)
Mount Hood, the highest peak in Oregon, is a glacier-covered stratovolcano known for its potential to erupt explosively or effusively. Though its last significant eruption was over 200 years ago, it remains seismically active. An eruption could melt glaciers and trigger lahars that threaten communities along the Columbia River. Its proximity to Portland and reliance on it for recreation and water resources increase the risk of societal disruption.
7. Three Sisters (Oregon)
The Three Sisters are a volcanic trio in central Oregon—North, Middle, and South Sister—each with distinct volcanic histories. South Sister has shown signs of ground uplift, suggesting magma intrusion. Though currently dormant, the area’s volcanic past and signs of unrest pose a future threat. The region is popular for recreation and close to the city of Bend, meaning even a moderate eruption could have significant local impacts.
8. Akutan Volcano (Alaska)
Akutan Volcano, located in the eastern Aleutians, is among Alaska’s most active volcanoes. Its eruptions are frequent and typically explosive, posing a threat to nearby air routes and the local community of Akutan. The volcano also has a geothermal area that produces steam and fumarolic activity. Though remote, its proximity to Unalaska and Dutch Harbor—key fishing industry hubs—makes Akutan a significant hazard in the region.
9. Makushin Volcano (Alaska)
Makushin Volcano is situated on Unalaska Island near Dutch Harbor, one of the busiest fishing ports in the U.S. Although its eruptions tend to be moderate, its frequent activity and the potential for large eruptions make it a concern. The volcano is ice-covered and shows signs of geothermal activity. An eruption could affect the nearby population and disrupt air travel and seafood operations critical to Alaska’s economy.
10. Mount Spurr (Alaska)
Mount Spurr is an active stratovolcano west of Anchorage, known for its explosive 1992 eruption that produced ash clouds disrupting aviation. It remains a critical concern due to its glacier-covered summit and frequent seismic activity. Though remote, it lies directly beneath major trans-Pacific flight routes. A significant eruption could create lahars and send ash into the heavily populated Anchorage area, making it one of the most closely watched Alaskan volcanoes.
11. Lassen Volcanic Center (California)
Lassen Volcanic Center in northern California last erupted in 1915, producing lava domes, pyroclastic flows, and ash. It features multiple geothermal areas and all four types of volcanoes. Though quiet today, it remains active and could erupt again, threatening nearby communities and infrastructure. The region’s hydrothermal systems, including boiling springs and fumaroles, show ongoing subsurface activity, making it a major hazard within the southern Cascade Range.
12. Augustine Volcano (Alaska)
Augustine Volcano, a steep-sided island volcano in Cook Inlet, has erupted multiple times since 1900, with the most recent in 2006. Its explosive activity can generate pyroclastic flows, ash plumes, and tsunamis. Despite its remote location, Augustine’s ash clouds pose a serious risk to aviation and nearby communities like Homer. The volcano’s active magma chamber and frequent unrest ensure it remains under continuous observation by volcanologists.
13. Newberry Volcano (Oregon)
Newberry Volcano is a large shield volcano with a massive caldera near Bend, Oregon. It last erupted about 1,300 years ago but remains active, with hot springs, fumaroles, and recent uplift. Unlike steep stratovolcanoes, it spreads over a vast area and is capable of both explosive and effusive eruptions. Future activity could impact local infrastructure, recreation areas, and air quality. It’s one of the largest volcanoes in the Cascades.
14. Crater Lake (Mount Mazama) (Oregon)
Crater Lake formed about 7,700 years ago when Mount Mazama collapsed after a massive eruption. The eruption ejected ash across North America and left a deep caldera now filled with water. Though dormant, Crater Lake’s magma chamber is not extinct, and future eruptions—though unlikely in the short term—could involve explosive activity or lava domes. It’s a high-threat system due to its cataclysmic past and active hydrothermal features.
15. Mount Baker (Washington)
Mount Baker, located in northwestern Washington, is an ice-clad volcano with a history of eruptions and frequent steam emissions. Although it hasn’t erupted since the mid-1800s, it remains active with fumaroles and seismic activity. Its glaciers could produce devastating lahars if disturbed by an eruption. Proximity to Bellingham and the Nooksack River basin heightens the threat, especially from flooding or mudflows that could reach populated valleys.
16. Glacier Peak (Washington)
Glacier Peak is a remote but dangerous stratovolcano in Washington’s Cascades, with a history of large, explosive eruptions. It produced massive lahars and ash deposits across the Puget Sound region thousands of years ago. Although it’s less well known than Mount Rainier, its eruptions are more explosive. Its inaccessibility makes monitoring difficult, but its potential to affect downstream communities and air traffic keeps it high on threat assessments.
17. Iliamna Volcano (Alaska)
Iliamna Volcano lies southwest of Anchorage and is characterized by frequent fumarolic activity and occasional seismic swarms. Although it hasn’t erupted in historical times, its persistent unrest signals that magma may be present. Covered in glaciers, Iliamna could produce lahars if it erupts. Its position along major air corridors and proximity to populated areas contribute to its high hazard potential, even though it’s less visibly active than others.
18. Long Valley Caldera (California)
Long Valley Caldera is one of the largest and most geologically complex volcanic systems in the U.S., formed by a supereruption about 760,000 years ago. Located near Mammoth Lakes, it continues to show signs of unrest through earthquake swarms, ground uplift, and geothermal activity. Though quiet since a small eruption 300 years ago, the caldera has the potential for large explosive eruptions, making it a top concern in eastern California.
19. Aniakchak Caldera (Alaska)
Aniakchak Caldera is a massive volcanic depression in a remote part of Alaska’s Aleutian Range, formed by a colossal eruption around 3,500 years ago. Despite its isolation, it is considered very dangerous due to its explosive history and potential to disrupt air traffic. The caldera includes a lake and recent lava domes. Its extreme remoteness complicates monitoring and response but doesn’t diminish its threat level due to its eruption scale.
20. Westdahl Volcano (Alaska)
Westdahl Volcano is located on Unimak Island in the Aleutians and last erupted in 1992. It’s known for producing lava flows and ash plumes. Though not heavily populated nearby, its eruptions could disrupt trans-Pacific flights. Westdahl’s volcanic complex remains seismically active and closely monitored. Eruptions could impact remote installations or marine navigation. Its potential for further eruptions, even after long quiet periods, places it in the high-threat category.
21. Fisher Caldera (Alaska)
Fisher Caldera on Unimak Island was the site of one of the largest eruptions in U.S. history around 8700 years ago. While currently quiet, it retains the potential for massive explosive eruptions. Its remoteness masks its hazard to trans-Pacific flights and potential regional ashfall. Its caldera-forming past and little modern activity make it difficult to study, but its eruption history places it among the highest volcanic threats in Alaska.
22. Korovin Volcano (Alaska)
Korovin is a frequently active stratovolcano on Atka Island in the Aleutians. Its regular small eruptions and emissions pose a hazard to aircraft traveling over the North Pacific. Although it doesn’t threaten large populations directly, the nearby community of Atka could be affected. Korovin has shown ongoing seismic unrest and gas emissions, which are monitored closely due to its consistent activity and the possibility of stronger, unexpected eruptions.
23. Okmok Caldera (Alaska)
Okmok is a broad caldera on Umnak Island with a history of explosive eruptions, including a major event in 2008. The eruption filled the caldera with lava and ash, affecting air routes and blanketing nearby areas. The volcano remains seismically active and capable of large-scale events. Though the region is sparsely populated, Okmok’s frequent unrest and potential for large eruptions make it a critical hazard for aviation and research.
24. Veniaminof Volcano (Alaska)
Veniaminof is a massive, glacier-covered stratovolcano on the Alaska Peninsula, notable for eruptions in 2018 and earlier. It features a large caldera and an active central cone that produces ash and lava. Its remote location reduces direct population risk, but its size and frequent activity pose aviation hazards. The volcano is monitored for sudden changes that could lead to more significant eruptions, particularly due to its ice-covered structure.
25. Pavlof Volcano (Alaska)
Pavlof is one of the most consistently active volcanoes in Alaska, with numerous eruptions, including as recently as 2023. Its steep profile and frequent explosive activity generate ash clouds that disrupt air travel. Located near Cold Bay, Pavlof is closely monitored for signs of major events. Its accessibility and reliable unrest make it a prime candidate for hazard planning, especially due to its position under key air traffic routes.
26. Shishaldin Volcano (Alaska)
Shishaldin, the highest volcano in the Aleutians, is known for its nearly perfect conical shape and frequent strombolian eruptions. It erupted multiple times in recent years, producing lava fountains and ash plumes. Located on Unimak Island, it poses an ongoing aviation hazard. Its persistent activity and potential for stronger explosive eruptions place it among the most dangerous Alaskan volcanoes despite its remoteness from large population centers.
27. Cleveland Volcano (Alaska)
Cleveland Volcano, situated on Chuginadak Island, frequently erupts with little warning, producing ash plumes that rise quickly into flight paths. Its remote, unmonitored summit increases the challenge of forecasting eruptions. Cleveland is one of Alaska’s most active volcanoes and is capable of larger explosive events that could threaten aircraft and distant communities. The combination of frequent, unpredictable activity and aviation risk keeps Cleveland on the high-alert list.
28. Great Sitkin Volcano (Alaska)
Great Sitkin, located near Adak Island in the Aleutians, resumed eruptive activity in 2021, producing lava flows and explosions. Though the eruptions have been relatively moderate, the potential for stronger explosive events exists. The volcano is monitored due to its proximity to Adak, a key military and logistics hub. Ongoing lava dome growth indicates that pressure may be building, maintaining concern over future, larger-scale activity.
29. Hayes Volcano (Alaska)
Hidden beneath thick ice in the Alaska Range, Hayes Volcano wasn’t even identified until the 1990s. Despite its obscurity, geological evidence shows it has had multiple large explosive eruptions over the past 10,000 years. No historical eruptions are recorded, but seismic activity in the region warrants attention. An eruption would likely generate significant ashfall and lahars, impacting remote regions and potentially threatening the Cook Inlet area.
30. Trident Volcano (Alaska)
Trident is a complex volcano within Katmai National Park and erupted multiple times in the 20th century. It lies near the site of the 1912 Novarupta eruption, the largest in modern U.S. history. Trident’s activity includes lava flows and ash emissions, often affecting the surrounding wilderness and airspace. Its proximity to the popular Brooks Camp area and aviation routes keeps it under active surveillance despite its isolated location.
31. South Sister (Oregon)
South Sister is the most recently active of the Three Sisters in central Oregon. While it hasn’t erupted in over a millennium, recent ground uplift and seismic activity suggest magma movement. The potential for explosive eruptions and proximity to cities like Bend and recreational areas make it a concern. Its role in a broader volcanic system increases the complexity of forecasting, warranting close monitoring for signs of reactivation.
32. Reid Island Volcano (Alaska)
Reid Island Volcano is a poorly studied, remote volcanic center in the Aleutians. While no historic eruptions are known, its geologic features suggest the possibility of explosive activity. The lack of instrumentation and remoteness make it difficult to monitor or assess its full hazard potential. However, its inclusion on high-threat lists stems from its capacity for eruptions that could affect regional airspace and marine traffic unexpectedly.
33. Katmai Volcano (Alaska)
Katmai is famous for the 1912 eruption of nearby Novarupta, which created the Valley of Ten Thousand Smokes and is the largest 20th-century eruption globally. Katmai itself collapsed into a massive caldera during this event. While quiet since, it’s part of an active volcanic region with strong geothermal activity. Its historical power and potential for renewed activity, along with its tourist popularity, make it a significant ongoing hazard.
34. Medicine Lake Volcano (California)
Medicine Lake Volcano is a large shield volcano in northeastern California, with a vast area but relatively quiet eruptions. Its past activity includes lava flows and small explosions. Though not highly explosive, the volcano’s size and proximity to towns like Tulelake and Alturas make it important to monitor. Its geothermal features and history of slow-moving lava flows still present long-term risks to surrounding communities and ecosystems.
35. Mono-Inyo Craters (California)
The Mono-Inyo Craters chain includes domes, fissures, and explosion pits formed by violent eruptions over the past 40,000 years. The most recent eruptions occurred around 600 years ago and produced pyroclastic flows and domes. Located near Mammoth Lakes, the area is seismically active and geothermally heated, suggesting the magma system is still active. Future eruptions could be explosive, affecting tourism, water supplies, and local air quality.
36. Adagdak Volcano (Alaska)
Adagdak Volcano is a heavily eroded volcanic complex on Adak Island. It hasn’t erupted in historical times, but fumarolic activity and volcanic deposits confirm past eruptions. Though less of an immediate hazard than others, its proximity to Adak’s military and civilian infrastructure warrants monitoring. Erosion has masked some of its features, making hazard assessment difficult. If it reactivates, explosive activity and localized impacts would be possible.
37. Seguam Island Volcano (Alaska)
Seguam Island contains multiple overlapping volcanic cones, with frequent small eruptions and occasional larger events. The island is remote but sits along important North Pacific air routes. The volcano’s regular activity, including lava flows and ash plumes, makes it a persistent hazard to aircraft. Though it poses minimal risk to people directly, Seguam’s capacity for explosive eruptions in a poorly monitored region raises concern for aviation safety.
38. Chagulak Volcano (Alaska)
Chagulak is a stratovolcano on an isolated island in the Aleutians, largely unstudied due to its remoteness. No historical eruptions are known, but its youthful structure and volcanic deposits suggest potential activity. The lack of monitoring data and limited field access obscure its threat profile. However, if it were to erupt, the primary hazard would be ash clouds disrupting trans-Pacific flights and possibly affecting nearby maritime navigation routes.
39. Tanaga Volcano (Alaska)
Tanaga is an active stratovolcano on Tanaga Island with recent eruptions, including one in 2023. It has produced both explosive and effusive events. While unpopulated locally, its frequent unrest and potential for high-altitude ash plumes make it a concern for aircraft. Tanaga’s seismic swarms and gas emissions are monitored by the Alaska Volcano Observatory to assess risk and inform the aviation community of ongoing changes in activity.
40. Makushin’s Twin Peaks (Alaska)
Twin Peaks is part of the Makushin volcanic system on Unalaska Island. Though overshadowed by Makushin itself, it shows signs of past eruptions and shares geologic connections to the more active parts of the complex. The region’s geothermal activity suggests underlying heat and possible magma presence. If reactivated, Twin Peaks could pose localized threats to Dutch Harbor and aviation, especially given the area’s economic importance.
41. Kanaga Volcano (Alaska)
Kanaga Volcano is a steep-sided stratovolcano on Kanaga Island, known for its 1994 eruption. Its past activity includes lava flows and explosive events. The volcano’s symmetrical cone and active fumaroles indicate that magma remains beneath the surface. Though isolated, it is near key shipping lanes and air routes. Kanaga’s potential for explosive eruptions and poor monitoring coverage make it a persistent concern for volcanic hazard planning.
42. Ukinrek Maars (Alaska)
Ukinrek Maars erupted suddenly in 1977, forming two explosion craters over just 10 days. Located near Becharof Lake on the Alaska Peninsula, the eruption was small but violently explosive. It demonstrated how even little-known sites can erupt without warning. Though quiet since, the possibility of renewed activity, combined with the maars’ youth and unusual formation, makes them a geological curiosity and an enduring threat worth watching.
43. Tana Volcano (Alaska)
Tana is a relatively obscure volcanic complex in the central Aleutians. It has no confirmed historical eruptions but shows signs of past explosive activity. Its remote location and limited monitoring make it difficult to assess, but the presence of lava flows and caldera structures indicate potential for future hazards. If it were to erupt, the most likely consequences would be ash emissions affecting air traffic and local ecosystems.
44. Isanotski Peaks (Alaska)
Isanotski Peaks are part of a rugged volcanic complex near Unimak Pass. Although not frequently active in historic times, the area contains fumaroles and volcanic deposits suggesting past eruptions. The peaks are close to Pavlof Volcano and share geological features. The region’s remoteness belies its importance, as ash plumes from potential eruptions could disrupt major air and sea routes through the Aleutians and nearby communities.
45. Bogoslof Volcano (Alaska)
Bogoslof is a submarine volcano that erupted explosively from 2016 to 2017, rapidly reshaping its island. These violent events generated ash clouds that rose into commercial air corridors. Its underwater structure makes eruption forecasting extremely difficult. Though uninhabited, Bogoslof’s unpredictable nature, rapid landscape changes, and aviation threats make it one of the most hazardous volcanoes in the Aleutians despite its small size and remote location.
46. Mount Wrangell (Alaska)
Mount Wrangell is a massive shield volcano in Wrangell-St. Elias National Park. Though largely quiet, it continues to emit steam and gas from its summit, indicating ongoing heat below. It has erupted in the past few centuries, and its large size and glacier cover mean a future eruption could generate lahars or flooding. Its remoteness limits direct impact, but its size and activity level keep it on hazard lists.
47. Mount Edgecumbe (Alaska)
Mount Edgecumbe, near Sitka, Alaska, had been considered dormant until 2022 when magma movement caused ground uplift and earthquakes. Its last eruption occurred around 800–900 years ago. The volcano’s awakening startled locals and prompted renewed monitoring. If it erupts again, the proximity to Sitka could pose significant risk. Its reactivation highlights the need for vigilance even at seemingly quiet volcanic centers, especially those near population hubs.
48. Hualālai Volcano (Hawaii)
Hualālai is a potentially active volcano on Hawaii’s Big Island, last erupting in 1801. While dormant for over two centuries, it’s not extinct. Located near the Kona coast, an eruption could impact residential areas, resorts, and infrastructure. Lava flows remain the primary threat. Earthquakes and seismic swarms have been recorded, prompting concern over future activity. Its proximity to population centers makes it a notable volcanic hazard in Hawaii.
49. Mauna Loa (Hawaii)
Mauna Loa, the world’s largest volcano, erupted most recently in 2022 after nearly four decades of quiet. It produces large-volume lava flows that can reach the ocean and nearby communities. Its flanks are covered with lava from past eruptions that occurred with little warning. The volcano poses a major threat to infrastructure, roads, and homes on the Big Island. Constant monitoring is essential due to its sheer size and potential for widespread damage.
50. Mauna Kea (Hawaii)
Mauna Kea last erupted around 4,500 years ago but is still considered potentially active. It’s the tallest mountain on Earth when measured from seafloor to summit. Despite its dormancy, its past eruptions included lava flows that extended far from the summit. Scientific evidence shows it retains magma deep below. With observatories, highways, and towns nearby, Mauna Kea’s future eruptions, while unlikely soon, could still be possible.
Summary
The most dangerous volcanoes in the US are those with the highest likelihood of eruption. Sometimes, these volcanoes are part of mountain structures – overlooking cities and other populated areas. Other times, these volcanoes themselves are tourist attractions; drawing in people, and increasing the danger.