How volcanoes erupt

Stratovolcano Stratovolcanoes or composite volcanoes are tall conical mountains composed of lava flows and other ejecta in alternate layers, the strata that gives rise to the name.

How volcanoes erupt

A volcano is also a mountain formed by the accumulation How volcanoes erupt these eruptive products.

How volcanoes erupt

Volcanoes can and have existed on other worlds as well: Researchers are currently striving to find ways to predict when volcanic eruptions might happen on Earth by analyzing clues such as crystals and gases linked with volcanoes.

It is broken up into seven major and smaller pieces called tectonic plates, according to a paper by Christopher Harrison at the University of Miami.

These plates float on a layer of magma — semi-liquid rock and dissolved gases. At the boundaries of these plates — where they move past, are pushed under, or move away from each other — magma, which is lighter than the surrounding solid rock, is often able to force its way up through cracks and fissures.

Magma can explode from the vent, or it can flow out of the volcano like an overflowing cup. Magma that has erupted is called lava. They may occur as single volcanoes or as secondary volcanoes known as "parasitic cones" on the sides of stratovolcanoes or shield volcanoes.

Airborne fragments of lava, called tephra, are ejected from a single vent. The lava cools rapidly and fall as cinders that build up around the vent, forming a crater at the summit, according to the U.

Cinder cone volcanoes are fairly small, generally only about feet 91 meters tall and not rising more than 1, feet meters. They can build up over short periods of a few months or years. Stratovolcanoes are also called composite volcanoes because they are built of layers of alternating lava flow, ash and blocks of unmelted stone, according to the U.

They are larger than cinder cones, rising up to 8, feet 2, meters. Stratovolcanoes result from a conduit system of vents leading from a magma reservoir beneath the surface. When dormant, they typically have steep concave sides that sweep together at the top around a relatively small crater.

Stratovolcanoes can erupt with great violence. Pressure builds in the magma chamber as gases, under immense heat and pressure, are dissolved in the liquid rock.

When the magma reaches the conduits the pressure is released and the gases explode, like soda spewing out of a soda can that you shook up and opened suddenly, according to San Diego State University. Because they form in a system of underground conduits, stratovolcanoes may blow out the sides of the cone as well as the summit crater.

Stratovolcanoes are considered the most violent. Helensin Washington state, is a stratovolcano that erupted on May 18, Approximately square miles square kilometers of forest was completely obliterated and 57 people were killed. Over the course of the day, winds blew million tons of ash eastward across the United States and caused complete darkness in Spokane, Washington, miles kilometers from the volcano, according to the U.

Shield volcanoes are huge, gently sloping volcanoes built of very thin lava spreading out in all directions from a central vent.

They have wide bases several miles in diameter with steeper middle slopes and a flatter summit. Eruptions of these volcanoes are not generally explosive, but are more like liquid overflowing around the edges of a container.

Mauna Loa is about 55, feet 17, meters from its base beneath the ocean to the summit, which is 13, feet 4, meters above sea level. The most recent eruption was in Lava domes are built up when the lava is too viscous to flowaccording to the U.

A bubble or plug of cooling rock forms over a fissure. This cooler, thick lava usually rises near the end of an explosive eruption and lava domes often form within the craters of stratovolcanoes.

Helens has several well-defined lava domes inside the crateraccording to NASA. Other volcanic landforms Besides well-known symmetrical volcanoes such as Mount Fuji in Japan and Kilimanjaro in Tanzania, volcanic activity is responsible for several other distinctive landforms.

A caldera is a bowl-shaped depression formed when a volcano collapses into the void left when its magma chamber is emptied. There are three typesaccording to San Diego State University. The first type is a crater lake caldera.

Why are there volcanoes? Why do they erupt?

This is the result of a stratovolcano collapsing into its magma chamber during a violent eruption. Basaltic calderas have a concentric ring pattern resulting from a series of gradual collapses rather than a single event.

They are often found at the summit of shield volcanoes such as the craters at the tops of Mauna Loa and Kilauea. Resurgent calderas are the largest volcanic structures on Earth.

They are the result of catastrophic eruptions that dwarf any eruptions ever recorded by human beings.Feb 26,  · Before volcanoes erupt, the magma sloshes around in the upper mantle. Magma may cool and form igneous rocks and crystals below the surface, but it may also move into magma chambers, which are large pools of magma below the Earth's schwenkreis.coms: The Volcano Adventure Guide: Excellent information and background for anyone wishing to visit active volcanoes safely and book presents guidelines to .

May 04,  · Watch video · Hawaii's most active volcano: Here's the latest on Kilauea's eruption. Believe it or not, Kilauea has been erupting continuously since , with only occasional pauses of .

Volcanoes are as dangerous as they are majestic. Over 50 eruptions rock our planet every year. This video helps you understand what causes volcanoes to form and erupt—and shows where they are.

How volcanoes erupt

Volcanic eruptions can either be effusive or explosive. An effusive volcanic eruption occurs when the lava pours out onto the ground from the volcano's vent. When the molten rock or magma is thin and runny, gases can easily escape and the lava flows freely and travels far. An explosive volcanic. Scientists within the USGS Volcano Hazards Program operate from within five U.S.

volcano observatories. One of the primary goals of the observatories is to be an authoritative source for enlightening information about our Nation's volcanoes.

How Do Volcanoes Erupt? |