St. 5 hours and a Mount Pinatubo-sized eruption twice daily. The Global Volcanism Program (GVP) seeks better understanding of all volcanoes through documenting their eruptions--small as well as large--during the past 12,000 years. Geological Survey Volcano Hazards Program FAQs: "There are about 169 volcanoes in the United States that scientists consider active. 53; 14. and drifted as far as 2,255 km ESE during 31 October-1 November. 11. Out of an estimated 1,350 active volcanoes worldwide, about 45 have continuing eruptions, and about 80 erupt each year, spewing steam, ash, toxic gases, and. So, if you’re looking for an adventure that takes your breath away, climbing Acatenango is a must. Type of Volcano: Stratovolcano. Located off the coast of southern Italy, it is among the world's. More than a dozen volcanos are erupting at the same time worldwide, and. They add more land to the surface of the Earth and, when weathered, provide us with a nutrient-rich soil for agriculture. 63°E / 42. Without volcanoes, most of Earth's water would still be trapped in the crust and mantle. (Image credit: NASA. List of volcanoes in Italy. . Volcano: Directed by Mick Jackson. There are multiple types of volcanoes in Mexico. Explain that hotspots are not stable and do not remain at the same location at all times. Herðubreið 17 17. Structure of volcanoes. VOLCANO definition: 1. Mount Yasur, Vanuatu . Ash emissions, glowing lava bombs and emissions of steam and gas were ejected off the. Indeed, the type of volcanic eruption that occurs plays an important role in the evolution of a volcanic landform, thus forming a significant link between eruptive. destructive plate boundaries. S. Where the Batak people came from. Volcanoes often form a hill or mountain as layers of rock and ash build up from repeated eruptions. Bárðarbunga 3 3. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of. Panarea, view of the pier San Pietro, Stromboli Volcano and the Basiluzzo Island and Dattilo. Main page; Contents; Current events; Random article; About Wikipedia; Contact us; DonateThe shield volcano is an active volcano with a caldera that tends to erupt basalt lava. There are about 170 potentially active volcanoes in the United States and its territories. Total Number = 529 DORMANT – volcanoes that have not erupted during historical times, but willWhich of the following statements correctly describes a parasitic cone? -A parasitic cone is a small cone on the side or base of a volcano that has formed as a result of the ejection of pyroclastic materials. 10; 12. ALASKA VOLCANO OBSERVATORY DAILY UPDATE U. 16222°N 97. VOLCANO definition: 1. Geological Survey's Volcanoes and Current Activity Alerts map shows the location and activity levels of all volcanoes in the United States. S. The Earth's crust has 17 major, rigid tectonic plates. They may be the world’s most dynamic landforms,. Volcano Online is a website that offers various online games, such as lotto, casino, dogs and more. Ash plumes rose as high as 14 km (45,900 ft) a. Volcanic explosivity index. In this Guide, we will focus on eight stratovolcanoes featured on the Stratovolcanoes of the World poster available from. A volcano is an opening in a planet or moon’s crust through which molten rock, hot gases, and other materials erupt. Volcanoes can produce ash, toxic gases, flash floods of hot water and debris called lahars, lava flows, and fast-moving flows of hot gases and debris called pyroclastic flows. When a volcano erupts, hot gases and melted rock from deep within Earth find their way up to the surface. Magma is molten rock - rock that is so hot it has. Although ash is not highly toxic, it can trouble infants, the elderly, and those with respiratory ailments. The remaining two groups are volcanoes of Halmahera, including its surrounding volcanic islands, and volcanoes of Sulawesi and the Sangihe. We deliver forecasts, warnings, and information about volcano hazards based on a. Current activity map of Alaska and Kamchatka volcanoes. Eyjafjallajökull 8 8. Volcanoes do not typically occur at transform boundaries. Most of these are located in Alaska, where eruptions. Volcanoes [1] are formed by the movement of tectonic plates . Geological Survey assesses and monitors hazards at volcanoes within the United States and its territories. Two basic classifications of volcanoes are based upon the type of eruption they produce: explosive (or central) and quiet (or fissure). Our Volcanoes for Kids video is a fun and engaging way to introduce volcanoes to children. The papier-mâché volcano is a real classic, but there are many other ways to make an even more exciting and interesting science project focused on volcanoes! To get started on your own volcano-based science project, you will want to first have an understanding of how volcanoes form. Volcanism on the Moon is represented by the presence of volcanoes, pyroclastic deposits and vast lava plains on the lunar surface. Cone-shaped volcano with alternating layers of lava and pyroclastic material. Nevado del Ruiz, Colombia. Helens, United States. Sakurajima is one of the most active volcanoes in the entire world, and its last eruption of May 2, 2017 is considered to be one of the most recent eruptions by any of the Decade Sixteen. Katmai National Park and Preserve in Alaska is one of the world’s most active volcanic areas with 10 volcanoes that have had historic eruptions. List, map and overview of all active volcanoes in Indonesia: updates and information about Krakatau, Merapi, Bromo, Semeru, Rinjani, and many more. Most volcanic cones have one volcanic crater, or central depression, at the top. history. Below is an alphabetical list of volcanoes. Volcanoes Can Affect Climate. 4. Shield Volcanoes of Hawaii Poster. The great width of these volcanoes relative to their height is the result of the low viscosities of erupted lavas that produce thin widespread lava flows, eruptions from both the summit and fissure vents on the volcano’s flanks, and widening and subsidence along the summit and rift zones. Brennisteinsfjöll 4 4. Currently, the eruption of Kilauea is taking place in the Halema’uma’u crater. The Global Volcanism Program (GVP) seeks better understanding of all volcanoes through documenting their eruptions--small as well as large--during the past 12,000 years. 827; 14. The process of formation is known as cryovolcanism. Put simply, a volcano is an opening in the Earth’s surface. The latest data suggest a "significant likelihood of a volcanic eruption in the coming days". List of volcanoes in Nicaragua. Expert shares why so many volcanoes are erupting around the world. Fatalities from effusive volcanoes are rare because people can usually outrun the lava. OK. Volcano Calendar 2019. Volcano Name Country Type Latitude (dd) Longitude (dd) Elevation (m) Abu: Japan : Shield : 34. Iceland has declared a state of emergency and more than 3,000 residents have been urged to evacuate the small, coastal town of Grindavík as the country’s. There are typically 40-50 continuing eruptions, and out of those generally. They are very explosive and made of ash. However, human contributions to the carbon cycle are more than 100 times those from all the volcanoes in the world - combined. Etna (Sicily, Italy): The INGV volcano observatory reported an increasing strombolian-style activity from the Southeast Crater at 03:36 UTC last night. They are built from particles and blobs of congealed lava ejected from a single vent. Eruptions are rapid and violent, often spewing lava, ash and volcanic. Lava fountains rose as high has 1 km above the summit and. “Mt. 63 ( Amiata) / 40. Composite, shield, cinder cones, and supervolcanoes are the main types of volcanoes. Tephra and lava build up around. The cinder cones are small volcanoes with steep sides. List of volcanoes in Hawaii. Tall, steep, and symmetrical. 3. List of volcanoes in Martinique. As a precaution, the park has closed Chain of Craters Road at the. Shield. Prepare students by reviewing the sources of volcanism, namely, hotspots in the mantle and plate tectonics. Vocabulary. a correlation spectrometer. Mount Mayon last violently erupted in 2018, displacing thousands of villagers and coating nearby towns in thick layers of ash. Magma is rock. / | ListDate: November 21, 2023 Contact: Jessica Ferracane, (808) 985-6018 HAWAII NATIONAL PARK, Hawaiʻi – Kīlauea volcano in Hawaiʻi Volcanoes National Park is not erupting but is showing more signs of increased unrest as earthquakes spike in the upper East Rift Zone near Puhimau Crater. Geological Survey. • 9 min read. Poisonous: toxic; can hurt or kill you. What's erupting? List & map of currently active volcanoes Updated: Nov 24, 2023 09:42 GMT - 5 minutes ago refresh =major eruption =erupting =minor activity /. gov. Eyjafjallajökull, Iceland. Reduce visibility through smog and harmful gases that may threaten low-lying areas. Volcanoes erupt because of the way heat moves beneath Earth ’s surface. The map allows for filtering based on both location and current volcano status. Though the hike to the summit is no walk in the park, it’ll leave you with memories that'll. -A parasitic cone is a small cone within the crater of a volcano that has formed during repeated conduit eruptions. Volcano Name Country Type Latitude (dd) Longitude (dd) Elevation (m) Abu: Japan : Shield : 34. Abstract. Geological Survey Saturday, November 25, 2023, 12:30 PM AKST (Saturday, November 25, 2023, 21:30 UTC). Eruption of material at the surface. This volcano forms from particles of solidified lava that. The state of Hawaii is part of the Hawaiian-Emperor Seamount chain, which extends all across the Pacific Ocean. Supervolcanoes are like the supervillains of the geologic world, as stories of their looming threat grow ever more exaggerated. Matt Loewen, Acting Scientist-in-Charge, USGS mloewen@usgs. 139 ( Campi Flegrei) / 37. 1. Shishaldin Volcano, or Mount Shishaldin ( / ʃɪˈʃældən / ), is a moderately active volcano on Unimak Island in the Aleutian Islands chain of Alaska in the United States. Volcanic Iceland, roughly speaking, erupts every five years. 10°N 12. Magma: liquid rock inside the earth. Explain that hotspots are not stable and do not remain at the same location at all times. Volcanoes. The range of volcanic behavior is great. 827°N 14. Good sources for information about volcanoes outside the United States include Oregon State University's Volcano World and the Smithsonian. Ash: dust made of bits of burnt rock. Geological Survey California Volcano Observatory (USGS CalVO) was formed in 2012 and is headquartered in Menlo Park and Moffett Field, CA. It is also considered to be the most dangerous volcano in the Lower 48, with destructive lahars being the greatest geologic hazard. Major Types of Volcanic Cones Composite cones. Neptune’s largest moon, Triton, is home to a number of cryovolcanoes. Senior Writer, General Assignment. These plates are. . A number of other national parks contain volcanoes that have had prehistoric eruptions. Shield volcanoes do not have such violent eruptions. S. The highest volcano in Nicaragua is San Cristóbal with a height of 5,725 feet. 3 ± 0. KILAUEA VOLCANO (VNUM #332010) 19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m) Current Volcano Alert Level: ADVISORY Current Aviation Color Code:. The meaning of VOLCANO is a vent in the crust of the earth or another planet or a moon from which usually molten or hot rock and steam issue; also : a hill or mountain composed wholly or in part of the ejected material. Mount Shasta, California. The Volcanoes of New Mexico. Volcanology is the study of the generation and movement of molten rock on Earth and other planetary bodies, primarily through volcanoes and volcanic eruptions. National parks contain many of the best known and most scenic volcanoes in the United States: Mount Rainier, Crater Lake, Lassen Peak, Kīlauea, Sunset Crater Volcano, Yellowstone. (Image credit: NASA. CANBERRA, Australia — The eruption of Papua New Guinea’s tallest volcano subsided Tuesday, but thick ash still billowed into. There are four major types of volcanoes: cinder cone, composite, shield, and lava domes. C inder cones are the simplest type of volcano. The geology of the Canary Islands is dominated by volcanic rock. In the upper 10 km of rock beneath the conterminous United States, it. The Ring of Fire is a large circle of explosive volcanoes around the Pacific Ocean. Russia. An expert from USGS shares his insight on why this is happening all at the same time. 331 of the 1,350 volcanoes found globally are in the United States. 1 / 19. Composite volcanoes are tall, steep cones that produce explosive eruptions. Volcano - Magma, Eruptions, Geothermal: Geothermal energy is plentiful, but geothermal power is not. Kilauea has been erupting almost constantly from its eastern rift zone since 1983. Mount St. One way is "material spewing from the top of a mountain", but there are other forms as well. Up to 8,000 feet (2,400 meters) Roughly 6 degrees near the base and roughly 30 degrees near the top. The USGS Volcano Hazards Program enhances public safety and minimize social and economic disruption from volcanic unrest and eruption. At least eight units of the National Park System contain composite volcanoes, including. C. Pacific Ring Of Fire. 5. The Kingdom of Tonga, located in the South Pacific, experienced one of the biggest eruptions in recorded history in 2022. Volcanic activity worldwide 24 Nov 2023: Etna volcano, Fuego, Popocatépetl, Ibu, Dukono, Reykjanes,. There are three types of volcano. Helens-sized eruption produces every 2. Type. Walk on ancient lava beds. S. S. By Anna Skinner. Volcano - Eruptions, Magma, Structure: The shape and size of a volcano are controlled by several factors. Dormant volcano. Volcano - Magma, Eruptions, Geothermal: Geothermal energy is plentiful, but geothermal power is not. - Volcanoes that erupted during 2022: 80. . In the wake of its recent fiery rampage, it's perhaps no surprise that Kīlauea in Hawaii tops the list as the most dangerous volcano in the U. 1. S. 4 Some Volcano Facts The total number of recognizable volcanoes is about 10,000 ACTIVE – volcanoes known to have erupted during historical times. These fiery peaks have belched up molten rock, hot ash, and gas since Earth formed billions of years ago. Eldfell 5 5. It tells a fictional story of a supereruption at Yellowstone. green NORMAL, 2023-11-01 20:26:32 UTC. That’s why mapping and predicting such hazards is crucial. Table of Contents show 1 1. The volcano is considered one of the most dangerous in the. Shield volcanoes have very gentle slopes of only a few percent that become even more gentle near the summit. indicates a volcano has been active within the last 2. Mount Rainier, Washington. is a Philippine national institution dedicated to provide information on the activities of volcanoes, earthquakes, and tsunamis, as well as other specialized information and services primarily for the protection of life and property and in support of economic, productivity, and sustainable development. In addition to volcanoes’ direct physical danger, they can also lead to power outages, poor air quality, wildfires, and disruptions to aviation. Shiveluch (Kamchatka) This volcano is one of the largest in the area and the one that has had the most violent eruptions. The island of Hawaii is home to four volcanoes monitored by volcanologists: Mauna Loa, Hualalai, Kilauea, and Mauna Kea. When the lava cools and hardens, it forms into the cone‐shaped mountain we think of as a volcano. Historically, it is the most active of the five volcanoes that together. On. S. Here are a few statistics (at last database update on 11 Oct 2023): - Volcanoes with continuing eruptions: 46. Geology. Arizona has seven volcanic fields, according to a publication by The University of Arizona's Arizona Geological Survey. Volcano Calendar 2019. The U. Naples - Castel Nuovo Maschio Angioino. Volcanic eruptions can cause disastrous loss of life and property. The Australian Museum respects and acknowledges the Gadigal people as the First. is being stressed by the northward movement of the Pacific Plate against the North America Plate, and the resulting. An intrusion is magma that moves up into a volcano without erupting. (shield volcano, caldera 2434 m / 7,985 ft) Newberry volcano east of the Cascade Range in Oregon, is one of the largest volcanoes on the US mainland. Volcanoes National Park is a national park in northwestern Rwanda. Volcanoes simultaneously erupting across the globe grabbed headlines this week, with eruptions recorded in Italy, Iceland, Japan, Mexico and Russia. [1] More than 300 million people (nearly 1 in 20) live in the shadow of active volcanoes, including Mount Vesuvius in Italy, Mount Rainier in the U. Learn about the major types of volcanoes, the geological process behind eruptions, and where the. The volcano's topographic contour lines are nearly perfect circles above 6,500 feet (1,981 m). On May 18, 1980, Mount Saint Helens experienced an explosive eruption, sending a column of ash, steam, and. Ebeko (Paramushir Island, Kuril Islands) Watch for possible. The most significant eruptions come from super volcanoes like Yellowstone or. Eighty miles west of Bogotá, Colombia, Nevado del Ruiz volcano stretches more than 17,000 feet into the air. Vent: opening to allow air, heat or steam to escape. Acatenango Volcano, Guatemala. Along with lava, volcanoes also release gases, ash, and, solid rock. Composite, AKA Strato. Toxic gases: Volcanoes also release toxic gasses, such as carbon dioxide, carbon monoxide, sulfur dioxide, and hydrogen chloride. A volcano is an opening on the surface of a planet or moon that allows material warmer than its surroundings to escape from its interior. It can be aerial or underwater. Not only did Io have volcanoes—they were active! This was the first time an erupting volcano had been found anywhere besides Earth. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Volcanic gases entering the atmosphere with tephra during eruption of Augustine Volcano, Alaska, 2006. A cryovolcano (sometimes informally called an ice volcano) is a type of volcano that erupts volatiles such as water, ammonia or methane into an extremely cold environment that is at or below their freezing point. Detailed quake stats. The five most dangerous volcanoes in the U. Volcanic eruptions are often discussed in relation to climate change because they release CO 2 (and other gases) into our atmosphere. When the Hunga Tonga-Hunga Ha'apai volcano erupted on January 15, 2022 in the South Pacific, it produced a shock wave felt around the world and triggered tsunamis in Tonga, Fiji, New Zealand. This video helps you understand what causes volcanoes to form. A volcano is an opening in the Earth’s crust that allows molten rock, gases, and debris to escape to the surface. Kīlauea (US: / ˌ k ɪ l ə ˈ w eɪ ə / KIL-ə-WAY-ə, Hawaiian: [kiːlɐwˈwɛjə]) is an active shield volcano in the Hawaiian Islands. Hofsjökull. miles) of forest. Pilot Knob (Austin, Texas) / 30. Overview Venus has more volcanoes than any other planet in the solar system. Shield volcanoes do not have such violent eruptions. The most powerful volcanic eruption observed in recent history was in 1815 at the Tambora. Volcanic eruptions can result in additional threats to health, such as floods, mudslides, power outages, drinking water contamination, and wildfires. NASA is unraveling Io's volcanic secrets. According to the U. It is only 1117 meters in height. Volcanism in the arc began about 37 million years ago; however, most of the. Askja 2 2. Besides water and air, volcanoes. Hot spots, areas in Earth's mantle that are hotter than. Material that flows to or reaches the ground comprises. Lava: the name for magma that has spewed from a volcano. Treehugger / Julie Bang. Shield. The meaning of VOLCANO is a vent in the crust of the earth or another planet or a moon from which usually molten or hot rock and steam issue; also : a hill or mountain composed wholly or in part of the ejected material. A volcano is an opening in a planet or moon’s crust through which molten rock, hot gases, and other materials erupt. 4. Two of the eruptions are considered some of the world's largest volcanic events. Volcanoes do not typically occur at transform boundaries. Canada has five potentially active volcanic areas, all of which are located in British Columbia and the Yukon Territory: the Garibaldi Volcanic Belt of southwest British Columbia (the northern extension of the American Cascade Arc) the Wells Gray-Clearwater volcanic field of. Cinder cones are the smallest volcanoes and result from accumulation of many small fragments of ejected. Most explosive volcanoes occur above subduction zones. Fri, 24 Nov 2023, 21:00. The following are geological features of volcanic activity: intrusive and extrusive igneous rock, volcanic necks, flood basalt plateaus, calderas and craters. Hekla 14 14. This molten rock is called magma when it is beneath the surface and lava when it erupts, or flows out, from a volcano. Russia. Eyjafjallajökull 8 8. There are volcanoes all around our solar system. A big question remains. Volcanic eruptions in Iceland lead scientists to startling disc…There are more than 1,500 potentially active volcanoes or volcanic areas around the world at any given time. Volcano News and Research. S. Earth's plates can also move away. They've created more than. Some volcanoes can produce eruptions so powerful they release oceans of dust and toxic gases into the air, blocking out sunlight and changing a planet. Volcanoes are powerful displays of Earth in action. In addition, about 10 percent of the more than 1,500 volcanoes that have erupted in the past 10,000 years are located in the United States. [1]1 day ago · Rwanda is a country of breathtaking landscapes and rich biodiversity, a perfect haven for wildlife enthusiasts. When a part of the earth's upper mantle or lower crust melts, magma forms. These volcanoes tend to have gentle slopes and their runnier lava spreads. California is host to every type of volcano. Hekla 14 14. Guadeloupe has only one recognized volcano, La Grande Soufrière. These float on a hotter, softer layer in its mantle. These volcanoes tend to have gentle slopes and their runnier lava spreads. Watch these forces at work. Mount Etna in Sicily, Italy, is an example of a composite volcano. Scientists have determined that three forces within Earth can create a volcano. Helens blew its top–and one whole side of the mountain–killing 60 people and leveling 600 square kilometers (232 sq. List of volcanoes in Honduras. Volcano Online Ancient people believed that volcanoes were under the control of the gods. Gases and igneous rocks shoot up and splash over or fill the. A volcano is a landform, a mountain, where molten rocks erupt through the surface of the planet. Volcano Sushi Bar & Hibachi (Norman) 3700 W Robinson St Suite 164, Norman, OK 73072, United States. Almost half the states in the U. An intense eruption at Klyuchevskoy began on 31 October, prompting KVERT to raise the Aviation Color Code to Red (the highest level on a four-color scale). Type. Additionally, students should understand how plates move over time and the effects of. To put it in perspective, while volcanic eruptions do contribute to an increase in atmospheric CO2, human activities release an amount of CO2 equivalent to what a Mount St. The term volcano can also refer to the landform created by the accumulation of solidified lava and volcanic debris near the vent. Published April 23, 2019 • 4 min read “To me, volcanoes are the most tangible phenomena showing that our planet is alive,” says volcanologist Arianna Soldati, a National. The cinder cone tends to be the least vicious, with the stratovolcano being the most deadly. 70°E / 37. Ash can be hazardous to grazing livestock and can damage or force the shutdown. one that has not erupted recently but is expected to do so again. Here is our list of the most amazing volcanoes in the world. Latest scientific research on how volcanoes work, predicting volcanic eruptions, climate change due to volcanic eruption and more. “It’s just mind boggling,” says David Sandwell, a marine geophysicist at the Scripps Institution of Oceanography, who helped lead the work. Helens is an active volcano comes under the category of the stratovolcano. Strictly speaking there are two broad types of volcano, a stratovolcano and a shield volcano, although there are lots of different volcanic features that can form from erupted magma (such as cinder cones or lava domes) as well processes that shape volcanoes. The name “shield volcano” originated from its Roman shield-like shape and is often broad and flatter than the other types of volcanoes. The Global Volcanism Program (GVP) seeks better understanding of all volcanoes through documenting their eruptions--small as well as large--during the past 12,000 years. 139°E / 40. Volcanoes hold very hot liquid called magma. . Other states include California, Oregon, Washington, and Hawaii among others. Kilauea, Hawaii. When this happens, some of the magma rises to the top. With a summit elevation of 3,794 metres (12,448 ft), it is located in the Ross. A volcano is an opening on the surface of a planet or moon that allows material warmer than its surroundings to escape from its interior. Geological Survey Wednesday, November 22, 2023, 9:07 AM HST (Wednesday, November 22, 2023, 19:07 UTC). Nov 14, 2023 at 1:21 PM EST. Cinder cones are the most common type of volcano in the National Park System. How to use volcano in a sentence. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. The most volcanically active world in the solar system, Jupiter's moon Io, may possess a global ocean of magma underneath its surface, as well as mysteriously warm. Natural Hazards Interactive Map. 2 miles north of the island of Grenada. The mission of the USGS Volcano Hazards Program is to enhance public safety and minimize social and economic disruption from volcanic unrest and eruption through our National Volcano Early Warning System. Follow evacuation or shelter orders. Heat is conveyed from the planet’s interior to its surface largely by convection —the transfer of heat by movement of a heated fluid. Enjoy this fun filled science lesson for kids on volcanoes! Join Mr. The severity of the hazard generally decreases with distance from the volcano vent. indicates a volcano was active in the Holocene. Volcanoes are formed by the movement of tectonic plates. Volcano - Eruptions, Types, Magma: Volcanoes are frequently classified by their size and shape (as is described in the section Volcanic landforms), but they can also be classified by their eruptive habits. The huge explosion caused ash, lava and other debris to be expelled from the side of the mountain. First, volcanic eruptions produce major quantities of carbon dioxide (CO 2 ), a gas known to. List of volcanoes in Mexico. Stratovolcanoes of the World Poster. Volcanoes spew hot, dangerous gases, ash, lava, and rock that are powerfully destructive. CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE U. can boast a volcano or two. NASA provides unique data products and insights to assist with mapping damage and tracking air quality impacts from volcanoes. Newhall of the United States Geological Survey and Stephen Self in 1982. Geological Survey defines a volcano as a vent in Earth's surface, either on land or on the seafloor, from which molten rock called magma, as well as ash and gases, can erupt or ooze. gov. An eruption can be explosive, sending material high into the sky. Significant Volcanic Eruptions Poster.