Tungurahua, also called the Black Giant, is one of Ecuador's most active volcanoes. Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive.
Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes. But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish.
There are volcanoes on every continent, even Antarctica. Some 1, volcanoes are still considered potentially active around the world today; of those—over 10 percent—sit within the boundaries of the United States. But each volcano is different. Some burst to life in explosive eruptions, like the eruption of Mount Pinatubo , and others burp rivers of lava in what's known as an effusive eruption, like the activity of Hawaii's Kilauea volcano. These differences are all thanks to the chemistry driving the molten activity.
Effusive eruptions are more common when the magma is less viscous, or runny, which allows gas to escape and the magma to flow down the volcano's slopes. Explosive eruptions, however, happen when viscous molten rock traps the gasses, building pressure until it violently breaks free. The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates—massive expanses of our planet's lithosphere that continually shift, bumping into one another.
When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone. As the descending landmass sinks deep into the Earth, temperatures and pressures climb, releasing water from the rocks.
The water slightly reduces the melting point of the overlying rock, forming magma that can work its way to the surface—the spark of life to reawaken a slumbering volcano. Not all volcanoes are related to subduction, however. Another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity —or a hotspot—in the middle of a tectonic plate can push up through the crust to form a volcano.
Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface. This mechanism is thought to be behind the Hawaii volcanic chain.
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.
They are generally found where tectonic plates come together or separate but they can also occur in the middle of plates due to volcanic hotspots. A volcanic eruption is when lava and gas are released from a volcano—sometimes explosively. The most dangerous type of eruption is called a 'glowing avalanche' which is when freshly erupted magma flows down the sides of a volcano.
They can travel quickly and reach temperatures of up to 1, degrees Fahrenheit. Other hazards include ash fall, and lahars mud or debris flows. Volcanoes often cause population displacement and food shortages. Learn your volcano risks and warning signs and look out for unusual physical changes around volcanoes, such as increased ash fall or vegetation drying up.
Learn and participate in early warning systems and develop plans for both evacuating and sheltering in place. Be aware of secondary hazards such as landslides, lahars mudflows , ash and thunderstorms. Protect your home from volcanic ash and cover water sources if time allows. Avoid driving during and after ash fall when visibility can be very low and roads are slippery.
Protect your lungs and eyes by wearing protective gear such as goggles and masks. 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. It produces violent large eruptions and often leads to pyroclastic flows and mudflows. The active Mount Agung volcano in Bali falls under this category.
A caldera volcano has a circular basin-shaped appearance and releases thick rhyolotic lava which is between to degrees Celsius. Its shape is due to the magnitude of its eruptions, which cause the magma chamber walls to collapse. This occurs as the entire chamber empties, leaving it unsupported and liable to cave in.
This process is cyclical, and does not mean the volcano is dormant. Cross-sections of 3 types of volcano. Vertical scale is somewhat exaggerated. More on:.
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