Why volcanic eruptions

Ash particles may contain crystalline silica, a material that causes a respiratory disease called silicosis. Most gases from a volcano quickly blow away. However, heavy gases such as carbon dioxide and hydrogen sulfide can collect in low-lying areas.

The most common volcanic gas is water vapor, followed by carbon dioxide and sulfur dioxide. Sulfur dioxide can cause breathing problems in both healthy people and people with asthma and other respiratory problems. Other volcanic gases include hydrogen chloride, carbon monoxide, and hydrogen fluoride. Amounts of these gases vary widely from one volcanic eruption to the next.

Although gases usually blow away rapidly, it is possible that people who are close to the volcano or who are in the low-lying areas downwind may be exposed to levels that may affect health. At low levels, gases can irritate the eyes, nose, and throat. At higher levels, gases can cause rapid breathing, headache, dizziness, swelling and spasm of the throat, and suffocation. Skip directly to site content Skip directly to page options Skip directly to A-Z link.

Natural Disasters and Severe Weather. Basaltic lava allows gas to escape easily, resulting in smaller eruptions, while andesitic and rhyolotic lava makes it harder for the gas to escape, leading to larger eruptions. Lava is often thought to be the main danger of a volcanic eruption, but this is not the case. Numerous hazards result from eruptions and they can have a range of consequences. The most dangerous are the pyroclastic clouds, which destroy anything in their path.

Other hazards include ash clouds, ash rain, mudslides, earthquakes, tsunamis, odd weather patterns and glacial flooding. Originally published by Cosmos as Why do volcanic eruptions occur? Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science.

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Share Tweet. What causes a volcanic eruption? Plate tectonics is, however, not the only cause of eruptions. What are the different types of volcano? There are three main types of volcano. A shield volcano has a flat dome-like appearance and releases basaltic lava in a gentle manner that is often slow and easy for humans to outrun.

A stratovolcano has the classic cone shape and releases andesitic magma. Safety is, however, always the primary concern because volcanoes can be dangerous places. USGS scientists try hard to understand the risk inherent in any situation, then train Will extinct volcanoes on the east coast of the U. The geologic forces that generated volcanoes in the eastern United States millions of years ago no longer exist.

Through plate tectonics, the eastern U. So new volcanic activity is not possible now or in Where is the largest active volcano in the world? Rising gradually to more than 4 km 2. Its submarine flanks descend to the sea floor an additional 5 km 3 mi , and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km 5 mi.

This makes the volcano's summit about 17 km What is the difference between "magma" and "lava"? Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth's surface.

What kind of school training do you need to become a volcanologist? There are many paths to becoming a volcanologist. Most include a college or graduate school education in a scientific or technical field, but the range of specialties is very large. Training in geology, geophysics, geochemistry, biology, biochemistry, mathematics, statistics, engineering, atmospheric science, remote sensing, and related fields can 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 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 How many active volcanoes are there on Earth?

There are about 1, potentially active volcanoes worldwide, aside from the continuous belts of volcanoes on the ocean floor at spreading centers like the Mid-Atlantic Ridge. About of those 1, volcanoes have erupted in historical time. Many of those are located along the Pacific Rim in what is known as the " Ring of Fire. 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 Filter Total Items: Year Published: When volcanoes fall down—Catastrophic collapse and debris avalanches Despite their seeming permanence, volcanoes are prone to catastrophic collapse that can affect vast areas in a matter of minutes.

Siebert, Lee; Reid, Mark E. View Citation. Siebert, L. Geological Survey Fact Sheet , 6 p. Stovall, Wendy K. 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: 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: A sight "fearfully grand": eruptions of Lassen Peak, California, to On May 22, , a large explosive eruption at the summit of Lassen Peak, California, the southernmost active volcano in the Cascade Range, devastated nearby areas and rained volcanic ash as far away as miles to the east.

Clynne, Michael A. Clynne, M. 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. 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: Geologic hazards at volcanoes Most volcano hazards are associated with eruptions. 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. Year Published: Volcanoes! Geological Survey. Year Published: What are volcano hazards? Myers, Bobbie; Brantley, Steven R. Myers, B. Geological Survey Fact Sheet —97, 2 p.