About 50-60 volcanoes erupt every year.
About half are effusive (lava flows) and half are explosive.|
(1) The 6th century Krakatoa eruption is still speculative, but it seems to be the best explanation for severe climate changes in 535-36.
|Where ||When ||VEI * ||Casualties||Comments
|Yellowstone ||2.1M, 1.3M, 0.6M |
|8|| ||2.1 mya Huckleberry Ridge Tuff, Big Bend Ridge, Snake River, and Red Mountains caldera segments. |
2,450 cu. km. (km3) of ash
|Yellowstone ||1.3M |
|7|| ||Mesa Falls Tuff, Henrys Fork Caldera |
|Long Valley, CA ||760,000 |
|7|| ||590 km3
|Yellowstone ||640,000 |
|8|| ||Lava Creek Tuff, Yellowstone Caldera |
|Toba, Sumatra, Indonesia ||73,000 years ago ||8 || || 2,800 km3 of ash.
|Mount Mazama, Oregon ||4650 B.C. || Plinian || ||Formed Crater Lake
|Taupo, New Zeland ||186 || || ||Pyroclastic flows travelled 100 km. More than 80 km3 of ash.
|Krakatoa, Indonesia ||c. 535 (1) ||6 || ||
|Tambora, Indonesia ||1815 ||7 ||38-92,000 ||Global climatic effects for several years. 50-150 km3 of ash.
|Krakatoa, Indonesia ||1883 ||6 ||37,000 ||Blast heard 5,000 km away. More killed by Tsunami. 10 km3
Martinique ||1902 ||? Pelean ||28,000 ||Pyroclastic Flow
Columbia ||1985 ||? ||23,000||Mudflow
|Unzen, Japan ||1720 ||? ||14,500
|Kelut, Java ||1586 ||? ||10,000
|Kelut, Java ||1919 ||? ||5,000
|Santa Maria, Guatemala ||1919 ||? ||4,000||Ash falls, Disease, Starvation
|El Chichon, Mexico ||1982 ||? ||1,800||Ash falls
|Laki, Iceland ||1783 ||? ||9,350
|Pinatubo, Philippines ||1991 ||6 Plinian ||800||4.8-10 km3
| Katmai (at
Novarupta), Alaska ||1912 ||6 ||? ||10 km3
|Mt. St. Helens, OR ||1980 ||5 Plinian||57||0.4-1 km3
Southern Chile ||1991 ||5||?
|| 1707-08 ||5||?
|Vesuvius, Italy || 79 AD ||5 Plinian||16,000||The famous Pompeii eruption.
|Mono-Inyo (Long Valley),
Calif. ||last 5,000 yrs. ||1-4 || ||About 20 small to moderate eruptions have occurred between Mammoth Lakes (Inyo) and Mono Lake in the last 5,000 years. The latest started about 600 years ago.
|Examples of Recent Smaller Volcanoes
|Shishaldin, Alaska ||1999 ||4||?||
|Rabaul, Papua New Guinea ||1994 ||4||?
|Augustine, Alaska ||1986 ||4||?
|Galunggung, Java, Indonesia ||1982 ||4||?
|Tungurahua, Ecuador ||2001 ||3||?
|Vesuvius ||1631 || ||4,000
|Tungurahua, Ecuador ||2001 || ||?
|Mono Lake (Long Valley), CA ||1750 ||?
|Lassen Peak, CA ||1915 ||3||?
|Mount Baker, WA ||1870 ||?||?
|Mount Hood, OR ||1865 ||?||?
|Mount Rainier, WA ||1820 ? ||?||?
|Mount Shasta, CA ||1786 ? ||?||?
|Mayon, Philippines ||1968 ||? Pelean||?
* Volcanic Explosivity Index (VEI) at USGS (U.S. Geological Survey) Volcanoes page
Source: Eruption Scale at U. North Dakota
|VEI ||Type ||Plume Height ||Volume ||Classification ||Frequency ||Example
|8 ||Megacolossal ||> 25 km ||>1000 km3 ||Ultra-Plinian ||>10,000 yr ||Yellowstone 2 Ma
|7 ||Supercolossal ||> 25 km ||>100 km3 ||Ultra-Plinian ||>1000 yr ||Tambora 1815
|6 ||Colassal ||> 25 km ||>10 km3 ||Plin/Ultra-Plinian ||>100 yr ||Krakatoa 1883
|5 ||Paroxysmal ||> 25 km ||>1 km3 ||Plinian ||>100 yr ||St Helens 1981
|4 ||Cataclysmic ||10-25 km ||>0.1 km3 ||Vulc/Plinian ||>10 yr ||Galunggung 1982
|3 ||Severe ||3-15 km ||>10.6 m3 ||Vulcanian ||yearly ||Ruiz 1985
|2 ||Explosive ||1-5 km ||>105 m3 ||Strom/Vulcanian ||weekly ||Galeras 1992
|1 ||Gentle ||100-1000 m ||>104 m3 ||Haw/Strombolian ||daily ||Sromboli
|0 ||non-explosive ||<100m ||>1,000 m3 ||Hawaiian ||daily ||Kilauea
See Also: VEI at the Smithsonian
U.S. Volcanoes since 1980
Source: An Assessment of Volcanic Threat and Monitoring Capabilities in the United States:
Framework for a National Volcano Early Warning System (NVEWS)
|VOLCANO ||ERUPTION YEAR ||UNREST EPISODE
|Hawaiian Volcano Observatory (HVO)|
|Kilauea, Hawaii ||1983-present ||
|Mauna Loa, Hawaii ||1984 ||2002-2004, inflation and deep seismicity
|Cascades Volcano Observatory|
|Mt. St. Helens, Washington ||1980-1986, 2004-2005 ||1989-2003, occasional earthquake bursts, minor phreatic explosions, small mudflows
|Mt. Hood, Oregon || ||Occasional earthquake swarms
|Three Sisters, Oregon || ||Uplift began 1997; earthquake swarm March 2004
|Medicine Lake, CA || ||1988-1989 earthquake swarm
|Long Valley Observatory (LVO>|
|Long Valley, California || || CA - In May of 1980, a strong earthquake swarm that included four magnitude 6 earthquakes struck the southern margin of Long Valley Caldera associated with a 25-cm, dome-shaped uplift of the caldera floor. CO2 emission from ground since 1989. Caldera unrest continues to this day, although earthquake activity within and adjacent to the caldera has remained low since mid-1999.
| Yellowstone Volcano Observatory (YVO) |
|Yellowstone National Park || ||Recurrent earthquake swarms and ground deformation (uplift & subsidence), changes in hydrothermal features. In April 2004 there was an increase in earthquake activity, called a swarm, at Yellowstone National Park that drew interest from scientists and the public. There have been many swarms recorded over the past 40 years at Yellowstone.
|Alaska Volcano Observatory|
|Redoubt, Alaska ||1989-1990 ||
|Spurr, Alaska ||1992 ||2004-2005 earthquake swarms and melt pit at summit. Overall rate of seismicity is diminishing.
|Augustine, Alaska ||1986 ||
|Iliamna, Alaska || ||1996 earthquake swarm and elevated gas emission
|Veniaminof, Alaska ||1983-1984, 1993-1995, 2004-2005 ||
|Pavlof, Alaska ||1980, 1981, 1983, 1986-1988, 1996-1997 ||
|Shishaldin, Alaska ||1986-1987, 1995-1996, 1999 ||2004-2005 earthquakes and tremor, thermal anomalies
|Westdahl, Alaska ||1991-1992 ||
|Dutton, Alaska || ||1984 earthquake swarm; 1988 earthquake swarm and intrusion
|Shrub Mud Volcano, Alaska || ||1996-1999 carbon dioxide/mud eruption
|Becharof Lake, Alaska || ||1998 earthquake swarm
|Chiginigak, Alaska || ||1997-1998 fumarolic activity
|Akutan, Alaska ||1980, 1987, 1988, 1992 ||Intense earthquake swarm and intrusion with ground cracks in 1996.
|Makushin, Alaska ||1980 ||
|Bogoslof, Alaska ||1992
|Okmok, Alaska ||1981, 1983, 1986-1988, 1997
|Cleveland, Alaska ||1986, 1987, 1994, 2001
|Amukta, Alaska ||1987, 1996?
|Seguam, Alaska ||1992, 1993
|Korovin, Alaska ||1987, 1998
|Kanaga, Alaska ||1993-1995
|Gareloi, Alaska ||1980, 1982
|Kiska, Alaska ||1987?
|Pagan, Mariana Islands ||1981-1996
|Anatahan, Mariana Islands ||2003-2005
Active Volcanoes Worldwide
Potential future re-activation of volcanoes in the United States
- Chikurachki, Russia
- Shiveluch, Russia
- Karymsky, Russia
- Anatahan, Mariana Islands
- Soufrière Hills, Montserrat
- Tungurahua, Ecuador
- Colima, México
- Kilauea, Hawaii, USA - Erupting since 1983.
- Mauna Loa, Hawaii, USA
- Mayon, Philippines
- Mt. St. Helens, Oregon - Erupted in 1980. Reawakened on Oct. 1, 2004. Growth of the new lava dome inside the crater of Mount St. Helens continues, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. Oct. 2005 code: Orange
See Volcanoes Hazards Updates, Smithsonian's Global Volcanism Program's (GVP).
At the USGS's An Assessment of Volcanic Threat and Monitoring Capabilities in the United States:
Framework for a National Volcano Early Warning System (NVEWS), (April, 2005), they categorize volcanoes by threat score. "Volcanic threat is the combination of hazards (the dangerous or destructive natural phenomena produced by a volcano) and exposure (the people and property at risk from the volcanic phenomena)."
The NVEWS threat assessment is not a formal risk assessment of U.S. volcanoes. The latter requires that probabilities of particular hazards occurring at individual volcanoes within a set time period be calculated and that the vulnerability of people and property to the hazards be estimated as expected losses in dollars. Such an analysis for so many volcanoes is beyond the scope of this work.
Their goal is to establish monitoring levels consistent with the threat. Currently only 3 of the 18 very high threat areas are well-monitored in real-time: Mount St. Helens, Washington; Kilauea, HI; and Long Valley caldera, CA. All 18 have at least a minimal level of ground based monitoring.
|Threat ||Num. ||Volcanoes
|Very High |
|18 ||Alaska: Akutan (AI), Augustine (CI), Makushin (AI), Redoubt (CI), Spurr (CI)
[Regions: Alaska Peninsula (AP), Aleutian islands (AI) Cook Inlet SW of Anchorage (CI)]
California: Lassen, Long Valley Caldera, Shasta
Hawaii: Kilauea, Mauna Loa
Oregon: Crater Lake, Hood, Newberry, South Sister
Washington: Baker, Glacier Peak, Rainier, St. Helens
|37 ||Alaska: Aniakchak (AP), Atka (AI), Churchill (Wrangell), Dutton (AP), Gareloi (AI), Great Sitkin (AI), Griggs (AP), Hayes (CI), Iliamna (CI), Kaguyak (AP), Kanaga (AI), Katmai (AP), Mageik, Martin, Novarupta, Okmok, Pavlof, Pavlof Sister, Seguam, Semisopochnoi, Shishaldin, Trident, Ugashik-Peulik, Veniaminof, Westdahl, Wrangell
California: Clear Lake, Inyo Craters, Medicine Lake, Mono Craters
Mariana Islands: Agrigan, Alamagan, Anatahan, Pagan,
|48 ||Alaska: Adagdak, Amak, Amukta, Black Peak, Bogoslof, Chiginigak, Cleveland, Dana, Denison, Douglas, Edgecumbe, Emmons Lake, Fisher, Frosty, Kasatochi, Kialagvik, Kiska, Kukak, Kupreanof, Little Sitkin, Moffett, Recheschnoi, Roundtop, Sanford, Snowy Mountain, Steller, Tanaga, Ukinrek Maars, Vsevidof, Yantarni, Yunaska,
Arizona: Sunset Crater
California: Coso Volc. Field, Mono Lake Volc Field, Red Cones, Ubehebe Craters
Hawaii: Haleakala, Mauna Kea
Mariana Islands: Asuncion, Farallon de Pajaros, Guguan, Sarigan
Nevada: Steamboat Springs (20 km south of Reno)
New Mexico: Valles Caldera
Oregon: Bachelor, North Sister Field
Utah: Black Rock Desert
|34 ||Alaska: Bobrof, Buldir, Buzzard Creek, Carlisle, Chagulak, Davidof, Duncan Canal. Fourpeaked, Herbert, Ingakslugwat Hills, Isanotski, Kagamil, Koniuji, Nunivak Island, Segula, Sergief, Stepovak, St.Michael, Table Top-Wide Bay, Takawangha, Uliaga, Unnamed
Idaho: Craters of the Moon, Hell's Half Acre, Shoshone Lava Field, Wapi Lava Field
Mariana Islands: Esmeralda Bank, Maug Islands, Ruby
Oregon: Belknap, Blue Lake Crater
Utah: Markagunt Plateau
Washington: Indian Heaven, West Crater
|Very Low |
|32 ||Alaska: Behm Canal-Rudyerd Bay, Gordon, Imuruk Lake, Kookooligit Mountains, St. Paul Island, Tlevak Strait-Suemez Island
Arizona: Uinkaret Field
California: Amboy, Big Cave, Brushy Butte, Eagle Lake Field, Golden Trout Creek, Lavic Lake, Tumble Buttes, Twin Buttes
Mariana Islands: Ahyi, Supply Reef
New Mexico: Carrizozo, Zuni-Bandera
Oregon: Cinnamon Butte, Davis Lake, Devils Garden, Diamond Craters, Four Craters Lava Field, Jackies Butte, Jefferson, Jordan Craters, Lava Mountain, Sand Mountain Field, Washington
Utah: Bald Knoll, Santa Clara
Map of Volcanoes of Canada and the western USA. at the Smithsonian.
A hotspot under yellowstone had created three supervolcanos;
There are 30 such hotspots, where magma is close to the surface, across the world, but yellowstone is the only one under land.
- 2.1 million years ago created a widespread volcanic deposit known as the Huckleberry Ridge Tuff. This titanic event, one of the five largest individual volcanic eruptions known anywhere on the Earth, formed a caldera more than 60 miles (100 km) across. 5.1 cubic miles mi3 of magma.
- A similar, smaller but still huge eruption occurred 1.3 million years ago. This eruption formed the Henrys Fork Caldera.
- 640,000 years ago created the 35-mile-wide, 50-mile-long (55 by 80 km) Yellowstone Caldera.
This hotspot was created 16 million years ago. During that time the north american plate has moved 400 miles over it and left a trail of eruptions from western Idaho to Yellowstone.
Since the last large eruption 640,000 years ago there have been 30 smaller lava flows, the latest 70,000 years ago.
See Yellowstone Volcano Observatory (YVO) a partnership among the U.S. , Geological Survey (USGS), Yellowstone National Park, and University of Utah
Volcanic History of Yellowstone,
Steam Explosions, Earthquakes, and Volcanic Eruptions - What's in Yellowstone's Future?
In 2005 the BBC and the Discovery Channel produced
docudrama and documentary, "Supervolcano", about Yellowstone.
See: Weekly Volcanic Activity Report at the Smithsonian
Active and Potentially Active Volcanoes in California
Ejecta: Material that is thrown out by a volcano, including pyroclastic material (tephra) and lava bombs.
Lava: Magma which has reached the surface through a volcanic eruption. The term is most commonly applied to streams of liquid rock that flow from a crater or fissure. It also refers to cooled and solidified rock.
Magma: Molten rock beneath the surface of the earth.
Pyroclastic: Pertaining to fragmented (clastic) rock material formed by a volcanic explosion or ejection from a volcanic vent.
Pyroclastic Flow (nuées ardentes): Lateral flowage of a turbulent mixture of hot gases and unsorted pyroclastic material (volcanic fragments, crystals, ash, pumice, and glass shards) that can move at high speed (100 to 500 miles an hour.) The term also can refer to the deposit so formed. Types.
Tuff: Rock formed of pyroclastic material.
Type of eruption:
- Named after the Italian volcano, Stromboli, eject small to medium sized lava fragments to form incandescent arcs which can be traced in photographs. Cinder cones often use this eruptive style.
- Named for the Italian volcano, Vulcano, produce short blast-like eruptions of gas and ash. These and all such eruptions occur due to the gas content of the magma being expelled.
- Named after the guy who reported Vesuvius to the Romans (Pliny the Younger), are the most violent there are. The most famous plinian eruption for Americans is probably the eruption of Mt. St. Helens. Plinian eruptions are long duration explosions which send ash and debris billowing kilometers into the atmosphere. Fine ash can be dispersed over very large areas. They typically last hours and can expel truly massive quantities of debris. Fast-moving deadly pyroclastic flows are also commonly associated with plinian eruptions.
- Similar to plinian, but are not so enormous. They release large amounts of ash and gas while the cloud typically forms a sort of cauliflower shape. Vesuvian eruptions are named after the Italian Mt. Vesuvius, which destroyed the cities of Pompeii and Herculaneum.
- Pelean [Peléean, Nuée Ardente (glowing cloud)]
- Pelean eruptions occur when the vent is held at an angle so that the eruption shoots out laterally, not up. Named for Mont Pelee in the West Indies.
Peleean eruption involve viscous magma and share characteristics with Vulcanian eruptions. The key characteristic of Peleean eruptions is the eruption of glowing avalanches of hot ash.
Eruptions may occur along fissures or fractures that serve as linear vents, such as during the eruption of Mauna Loa Volcano in Hawaii in 1950; or they may occur at a central vent such as during the 1959 eruption in Kilauea Iki Crater of Kilauea Volcano, Hawaii. In fissure-type eruptions, molten, incandescent lava spurts from a fissure on the volcano's rift zone and feeds lava streams that flow downslope. In central-vent eruptions, a fountain of fiery lava spurts to a height of several hundred feet or more. Such lava may collect in old pit craters to form lava lakes, or form cones, or feed radiating flows.
- Phreatic (or steam-blast)
eruptions are driven by explosive expanding steam resulting from cold ground or surface water coming into contact with hot rock or magma. The distinguishing feature of phreatic explosions is that they only blast out fragments of preexisting solid rock from the volcanic conduit; no new magma is erupted. Phreatic activity is generally weak, but can be quite violent in some cases, such as the 1965 eruption of Taal Volcano, Philippines, and the 1975-76 activity at La Soufri¸re, Guadeloupe (Lesser Antilles).
Sources: Types of Volcanic Erujptions, Basics of Volcanology, Kinds Of Volcanic Eruptions
See: Volcanic and Geologic Terms
Index to Volcanoes at the USGS Cascades Volcano Observatory (CVO), Vancouver, Washington
The Smithsonian Institution Global Volcanism Program : Volcanoes of the World (Region Map,
Weekly World Volcanic Activity Report & Activity Map)
Top Ten Earthquakes and Volcanic Eruptions
Volcanoes at MTU
Volcano Live by John Seach, Australia
last updated 4 Oct 2005