Hotspot volcanoes

Gacad: volcanoes explained – SUNSTAR

THE VOLCANOES are the geological architects of the Earth. They created over 80 percent of our planet’s surface, laying the foundation that allowed life to thrive. Their explosive force makes mountains as well as craters. Rivers of lava spread across dark landscapes. But as time passes, the elements break down these volcanic rocks, releasing nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to thrive.

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active in the world today. But every volcano is different.

Some were brought to life in explosive eruptions, like the eruption of Mount Pinatubo in 1991, and others burp rivers of lava in what is called an effusive eruption, like the 2018 activity of the Kilauea volcano in Hawaii.

These differences are all due to the chemistry behind the molten activity.

Effusive eruptions are more common when the magma is less viscous or flowing, allowing gas to escape and magma to flow down the slopes of the volcano. However, explosive eruptions occur when viscous molten rock traps gases, creating pressure until it is violently released.

The majority of the world’s volcanoes form along the boundaries of the vast massive expanses of the Earth’s tectonic plates of our planet’s lithosphere that are continually moving, colliding with each other.

When tectonic plates collide, one often plunges deep below the other in what is called a subduction zone. As the descending landmass sinks deep into the Earth, temperatures and pressures rise, releasing water from the rocks. The water slightly reduces the melting point of the overlying rock, forming magma that can rise to the surface. However, not all volcanoes are related to subduction.

Another way volcanoes can form is known as hot spot volcanism. In this situation, an area of ​​magmatic activity or a hot spot in the middle of a tectonic plate can rise through the crust to form a volcano. Although the hotspot itself is considered largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface.

Some 75 percent of the world’s active volcanoes are positioned around the Ring of Fire, a 25,000-mile-long horseshoe-shaped area that stretches from the southern tip of South America to the coast. western North America, passing through the Bering Sea to Japan, then New Zealand. This region is where the edges of the Pacific and Nazca plates collide with a set of other tectonic plates.

Importantly, however, the ring volcanoes are not geologically connected. In other words, a volcanic eruption in Indonesia is unrelated to an eruption in Alaska, and it couldn’t stir up the infamous Yellowstone supervolcano.

Volcanic eruptions present many dangers apart from lava flows. It is important to heed the advice of local authorities during active eruptions and to evacuate areas if necessary.

A particular danger is created by pyroclastic flows, avalanches of hot rocks, ash and toxic gases that hurtle down slopes at speeds of up to 450 miles per hour. Likewise, volcanic mudslides called lahars can be very destructive. These swift waves of mud and debris can hurtle down the sides of a volcano, burying entire cities.

Ash is another volcanic hazard. Unlike the soft, fluffy pieces of charred wood left behind after a campfire, volcanic ash is made up of sharp fragments of rock and volcanic glass less than two millimeters in diameter each. Ashes form as gases in the rising magma expand, breaking up cooling rocks as they spring from the volcano’s mouth. Not only is it dangerous to inhale, it is also heavy and accumulates quickly. Volcanic ash can collapse weak structures, cause power outages, and is a challenge to remove after an eruption.

Volcanoes give warning of an impending eruption, making it vital for scientists to closely monitor all volcanoes near major population centers. Warning signs include small earthquakes, swelling or bulging of the volcano’s flanks, and increased gas emissions from its vents. None of these signs necessarily mean an eruption is imminent, but they can help scientists assess the condition of the volcano when magma forms.

However, it is impossible to say exactly when, or even if, a given volcano will erupt. Volcanoes do not operate on a schedule like a train. This means that it’s impossible for someone to be “late” for a rash no matter what the headlines say.

The deadliest eruption in recorded history was the 1815 Mount Tabora explosion in Indonesia. The explosion was one of the most powerful ever documented and created a caldera that is essentially a crater four miles in diameter and over 3,600 feet deep.

A superheated plume of hot ash and gas was hurled 45 kilometers into the sky, producing numerous pyroclastic flows as it collapsed.

The eruption and its immediate dangers killed around 10,000 people. But that wasn’t his only impact. Volcanic ash and gas injected into the atmosphere obscured the sun and increased the reflectivity of the Earth, cooling its surface and causing what is known as the year without summer.

Famine and disease during this period killed an additional 82,000 people. Although there have been several large eruptions in recorded history, volcanic eruptions today are no more frequent than they were a decade or even a century ago. At least a dozen volcanoes erupt every day. As monitoring capacity and interest in volcanic eruptions increases, coverage of the activity appears more frequently in the news and on social media.

“The world isn’t more volcanically active, we’re just more aware of volcanism.” | -Erik Klemetti, associate professor of geosciences at Denison University

(Source: Maya Wei-Haas, “Volcanoes, Explained”

“The fact that a cloud from a minor volcanic eruption in Iceland, a small disturbance in the complex mechanism of life on Earth can stop air traffic across an entire continent is a reminder of how, with all its power to transform nature, humanity remains just another species on planet Earth. ” ~ Slavoj éiûek

“Despite our affinity and oneness with nature, all the evidence suggests that nature doesn’t care about us at all. Tornadoes, hurricanes, floods, earthquakes and volcanic eruptions happen without the slightest consideration. for human inhabitants. “~ Alan Lightman