How many volcanoes are there

Downloaded 11 Nov How many active volcanoes are there? What volcanoes have the most people living nearby? What volcanoes have had the longest eruptions? Has volcanic activity been increasing? What are some benefits of volcanic eruptions? Over geologic time, volcanic eruptions and related processes have directly and indirectly benefited mankind: Volcanic materials ultimately break down and weather to form some of the most fertile soils on Earth, cultivation of which has produced abundant food and fostered civilizations.

The internal heat associated with young volcanic systems has Can an eruption at one volcano trigger an eruption at another volcano? There are a few historic examples of simultaneous eruptions from volcanoes or volcanic vents located within about 10 kilometers 6 miles of each other, but it's difficult to Do volcanoes affect weather? Yes, volcanoes can affect weather and the Earth's climate.

Following the eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that Filter Total Items: Stovall, Wendy K. View Citation. Stovall, W. Geological Survey Fact Sheet —, 6 p.

Year Published: update to the U. Geological Survey national volcanic threat assessment When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location.

Ewert, John W. Ewert, J. Geological Survey national volcanic threat assessment: U. Geological Survey Scientific Investigations Report —, 40 p. Year Published: The Volcano Disaster Assistance Program—Helping to save lives worldwide for more than 30 years What do you do when a sleeping volcano roars back to life?

Lowenstern, Jacob B. Lowenstern, J. Year Published: U. Geological Survey Volcano Hazards Program—Assess, forecast, prepare, engage At least volcanoes in 12 States and 2 territories have erupted in the past 12, years and have the potential to erupt again.

Geological Survey Fact Sheet —, 4 p. Year Published: Eruptions of Hawaiian volcanoes - Past, present, and future Viewing an erupting volcano is a memorable experience, one that has inspired fear, superstition, worship, curiosity, and fascination since before the dawn of civilization. Tilling, Robert I. Venezky, Dina Y. Year Published: Eruptions in the Cascade Range during the past 4, years Volcanoes have been erupting in the Cascade Range for over , years.

Myers, Bobbie; Driedger, Carolyn L. Year Published: This dynamic planet: World map of volcanoes, earthquakes, impact craters and plate tectonics Our Earth is a dynamic planet, as clearly illustrated on the main map by its topography, over volcanoes, 44, earthquakes, and impact craters. Simkin, Tom; Tilling, Robert I. Dzurisin, Daniel; Stauffer, Peter H. Year Published: This dynamic earth: the story of plate tectonics In the early s, the emergence of the theory of plate tectonics started a revolution in the earth sciences.

Kious, W. Jacquelyne; Tilling, Robert I. While most volcanoes occur around borders of moving plates, they can also occur in the middle of plates too. In Hawaii, a hot spot in the middle of the Pacific plate allows magma to reach the surface in a weakness in the plate there.

In East Africa, spreading and shifting of plates has created the modern day Middle East there while also creating an area ripe with volcanic activity.

While plate tectonics helped sheer Saudi Arabia off of the African continent, creating the Red Sea in the process, the continental crust continues to stretch thin in this area. With the crust thinning there, magma below the surface is able to work its way through cracks and weaknesses in the thin crust, creating many volcanoes there. Alaska is home to many volcanoes, though; there are more than volcanoes and volcanic fields which have been active within the geologically young last 2 million years.

Another place famous for its volcanoes is Hawaii; on the Big Island of Hawaii, Kilauea, Mauna Loa, and Hualalai are considered active and potential threats, however none are erupting as of today. Kilauea did start a fresh eruption in December , but that eruption came to an end just weeks ago. The most famous is Mount St.

The Mount St. Helens eruption of was by far the most noteworthy in the U. Another notable erupting volcano is Lassen Peak in California. A series of steam blasts began on May 30, and an eruption occurred 12 months later on May 21, Minor activity continued there through the middle of After being dormant for over 1, years, Mount Hood in Oregon has an eruptive period beginning in that lasted for about a decade.

Some 75 percent of the world's active volcanoes are positioned around the ring of fire , a 25,mile long, horseshoe-shaped zone that stretches from the southern tip of South America across the West Coast of North America, through the Bering Sea to Japan, and on to New Zealand.

This region is where the edges of the Pacific and Nazca plates butt up against an array of other tectonic plates. Importantly, however, the volcanoes of the ring aren't geologically connected. In other words, a volcanic eruption in Indonesia is not related to one in Alaska, and it could not stir the infamous Yellowstone supervolcano.

Volcanic eruptions pose many dangers aside from lava flows. It's important to heed local authorities' advice during active eruptions and evacuate regions when necessary. One particular danger is pyroclastic flows, avalanches of hot rocks, ash, and toxic gas that race down slopes at speeds as high as miles an hour. Such an event was responsible for wiping out the people of Pompeii and Herculaneum after Mount Vesuvius erupted in A.

Similarly, volcanic mudflows called lahars can be very destructive. These fast-flowing waves of mud and debris can race down a volcano's flanks, burying entire towns. Ash is another volcanic danger.

Unlike the soft, fluffy bits of charred wood left after a campfire, volcanic ash is made of sharp fragments of rocks and volcanic glass each less than two millimeters across. The ash forms as the gasses within rising magma expand, shattering the cooling rocks as they burst from the volcano's mouth.

It's not only dangerous to inhale , it's heavy and builds up quickly. Volcanic ash can collapse weak structures, cause power outages, and is a challenge to shovel away post-eruption.

Volcanoes give some warning of pending eruption, making it vital for scientists to closely monitor any volcanoes near large population centers.

Warning signs include small earthquakes, swelling or bulging of the volcano's sides, and increased emission of gasses from its vents. None of those signs necessarily mean an eruption is imminent, but they can help scientists evaluate the state of the volcano when magma is building. However, it's impossible to say exactly when, or even if, any given volcano will erupt. Volcanoes don't run on a timetable like a train. The deadliest eruption in recorded history was the explosion of Mount Tabora in Indonesia.

The blast was one of the most powerful ever documented and created a caldera —essentially a crater—4 miles across and more than 3, feet deep.