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What Does Volcano Mean In Geography

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Geography Lesson: What is a Volcano? | Twig


In 2019, Alert Level 1 was raised on the volcano because of frequent volcanic activities since March. Based on the 24-hour monitoring of the Taal Volcano’s seismic network, 57 volcanic earthquakes were observed from the morning of November 11 to the morning of November 12.

The volcano erupted on the afternoon of January 12, 2020, with the alert level of the Philippine Institute of Volcanology and Seismology escalating from Alert Level 2 to Alert Level 4. It was an eruption from the main crater on Volcano Island. The eruption spewed ashes to Calabarzon, Metro Manila, some parts of Central Luzon, and Pangasinan, in the Ilocos Region, which cancelled classes, work schedules, and flights. Ashfalls and volcanic thunderstorms were reported, and forced evacuations were made from the island. There were also warnings of a possible volcanic tsunami. The volcano produced volcanic lightning above its crater with ash clouds. The eruption progressed into magmatic eruption, characterized by a lava fountain with thunder and lightning. By January 26, 2020, PHIVOLCS observed an inconsistent, but decreasing volcanic activity in Taal, prompting the agency to downgrade its warning to Alert Level 3. On February 14, 2020, PHIVOLCS downgraded the volcano’s warning to Alert Level 2, due to consistent decreased volcanic activity. A total of 39 people died in the eruption, mostly because they refused to leave their homes or suffered health-related problems during the evacuation.


Can We Predict Volcanic Eruptions

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. This means it’s impossible for one to be overdue for eruptionno matter what news headlines say.

See a Spectacular Lava “Waterfall” Pour Into the Ocean

A Scientific Look At Volcanic Eruptions

Volcanic eruptions are usually heralded by earthquake swarms. They indicate the motion of molten rock beneath the surface. Once an eruption is about to happen, the volcano can spew out lava in two forms, plus ash, and heated gases.

Most people are familiar with the sinuous-looking ropy “pahoehoe” lava . It has the consistency of molten peanut butter. It cools very quickly to make thick black rock layers. The other type of lava that flows from volcanoes is called “A’a” . It looks like a moving pile of coal clinkers.

Both types of lava carry gases, which they release as they flow. Their temperatures can be more than 1,200° C. The hot gases released in volcanic eruptions include carbon dioxide, sulfur dioxide, nitrogen, argon, methane, and carbon monoxide, as well as water vapor. Ash, which can be as small as dust particles and large as rocks and pebbles, is made of cooled rock and is flung out from the volcano. These gases can be quite deadly, even in small amounts, even on a relatively quiet mountain.

In very explosive volcanic eruptions, ash and gases are mixed together in what’s called a “pyroclastic flow”. Such a mixture moves very fast and can be quite deadly. During the eruption of Mt. St. Helens in Washington, the blast from Mount Pinatubo in the Philippines, and the eruptions near Pompeii in ancient Rome, most people died when they were overcome by such killer gas and ash flows. Others were buried in the ash or mud floods that followed the eruption.

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What Are Some Of The Dangers From A Volcano

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 450 miles an hour. Such an event was responsible for wiping out the people of Pompeii and Herculaneum after Mount Vesuvius erupted in A.D. 79.

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.

Shaping The Planets: Volcanism

Volcano " Science Fair"

What is volcanism?Volcanism is the eruption of molten rock onto the surface of a planet. A volcano is the vent through which magma and gases are discharged. Magma that reaches the surface is called âlava.â Volcanos are named for Vulcan â the Roman god of fire!

Why and where do volcanos form? Volcanism is the result of a planet losing its internal heat. Volcanos can form where rock near the surface becomes hot enough to melt. On Earth, this often happens in association with plate boundaries . Where two plates move apart, such as at mid-ocean volcanic ridges, material from Earth’s interior slowly rises up, melts when it reaches lower pressures, and fills in the gap. Where one plate is being subducted under another, chambers of magma may form. These magma bodies feed the volcanic islands that mark subduction zones.

Although most volcanic activity takes place at plate boundaries, volcanism also can occur within the plate interiors at hotspots. Hotspots are thought to be from large âplumesâ of extremely hot material rising from deep in Earth’s interior. The hot material rises slowly, eventually melting as it reaches lower pressures near Earth’s surface. When the material erupts it forms massive lava flows of fine-grained dark volcanic rock â basalt. The broad, gentle shield volcanos of Hawai’i come from a hotspot.

Dark regions on the Moon are lunar maria. These are low, smooth regions of dark, fine-grained volcanic rock â basalt.

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How Many Volcanoes Are There

USGS scientists monitor 161 active and potentially active volcanoes that are erupting now or could erupt at some point in the future. Most of these volcanoes are located in Alaska, a state where eruptions occur almost every year. The rest of the volcanoes are located throughout the American West, and in Hawaii . Klauea volcano on the Island of Hawaii is one of the most active volcanoes on Earth. It has been erupting almost nonstop since 1983!

East Summit is on the left skyline, and North Summit, to its right, is topped by an ice-filled crater from which a blocky dacite lava flow extends 1 km toward the camera. Central summit, the highest point on the mountain at just over 7,100 ft rises on the background skyline, 7 km southwest of North Summit. Alaska Volcano Observatory photo

There are about 1,350 potentially active volcanoes worldwide, not counting the volcanoes under the oceans. About 500 of these have erupted in the past 100 years. Many of these are located around the Pacific Ocean in what is known as the “Ring of Fire.” In the U.S., volcanoes along the west coast and in Alaska are part of the Ring of Fire, while Yellowstone and Hawaiian volcanoes form over a “hot spot.”

Volcanoes As Part Of Planetary Geology

Volcanoes are often closely related to continental plate movements. Deep under the surface of our planet, huge tectonic plates are slowly moving and jostling against each other. At the boundaries between plates, where two or more come together, magma creeps up to the surface. The volcanoes of the Pacific Rim have been built up this way, where plates slide together creating friction and heat, allowing lava to flow freely. Deep-sea volcanoes also erupt with magma and gases. We don’t always see the eruptions, but clouds of pumice eventually make their way to the surface and create long rock “rivers” on the surface.

As mentioned earlier, the Hawaiian islands are actually the result of what’s called a volcanic “plume” underneath the Pacific Plate. Here are some more scientific details about how that works: the Pacific Plate is moving slowly to the southeast, and as it does, the plume is heating the crust and sending material to the surface. As the plate moves southward, new spots are heated, and a new island gets built from molten lava forcing its way to the surface. The Big Island is the youngest of the islands to rise above the surface of the Pacific Ocean, although there’s a newer one being built as the plate slides. It’s called Loihi and it’s still underwater.

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Eruptions At Hot Spots

The chain of islands that form Hawaii lie at the centre of the Pacific Ocean, thousands of miles away from a plate margin. Hawaii was formed due to a volcanic hot spot. This is a fixed area of volcanic activity where magma rises from a mantle plume. As the Pacific Plate moves north-west over the plume huge amounts of basalt have accumulated on the ocean floor to produce the Hawaiian islands. As the plate moves away from the hot spot active volcanoes lose their source of magma and become extinct. Not all volcanoes that form at hot spots are shield volcanoes. El Tiede on Tenerife is a strato-volcano.

Reason Behind The Eruption Of Volcanoes:

GCSE Geography: Causes of Volcanoes

The volcano eruption begins with the formation of magma in the lower section of the earths crust. The earths crust is made up of massive slabs called plates, which fit together like a jigsaw puzzle. The friction during the movement of plates causes earthquakes and volcanic eruptions.

With pressure, it travels upwards with tremendous force hitting solid rocks and other material and creates a new passage to the earths surface. Once the magma reaches the air it is called lava.

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How Do Volcanoes Form

The majority of volcanoes in the world form along the boundaries of Earth’s tectonic platesmassive 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 surfacethe 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 activityor a hotspotin 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.

Follow a Lava Rivers Mesmerizing Path of Destruction

Volcanoes And Volcanic Eruptions

Volcanoes form when magma reaches the Earth’s surface, causing eruptions of lava and ash. Find out about different types of volcano, how to measure their strength and preparing for volcanoes.

Volcanoes can be described in terms of activity and can be:

  • still active and erupt frequently
  • dormant
  • extinct

Volcanoes can also be described by their shape or type – shield or composite.

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Volcanoes Are Necessary To Planetary Evolution

Volcanoes and volcanic flows have affected our planet since the earliest history of the solar system. They have enriched the atmosphere and soils, at the same time they have posed drastic changes and threatened life. They’re part of living on an active planet and have valuable lessons to teach on other worlds where the volcanic activity takes place.

Geologists study volcanic eruptions and related activities and work to classify each type of volcanic land feature. What they learn gives them more insight into the interior workings of our planet and other worlds where volcanic activity takes place.

Do You Know How To Prepare For A Volcanic Eruption

What causes a volcanic eruption?

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 , 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. Pay particular attention to vulnerable people and support them to evacuate or shelter in place.

Follow official instructions from local authorities on whether to evacuate or take shelter. If you get warning prior to ash fall, return home from school or work and shelter in place. If the ash fall is heavy, do not remain in a building that has a low-pitched or flat roof. Make sure you have additional supplies such as dust masks, eye protection, cleaning supplies, a flashlight and an evacuation bag to hand. Collect and store clean water and clean up outside carefully when it is declared safe to do so.

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Cumbre Vieja Lava Flows

Since Cumbre Vieja is located above a hotspot, the lava associated with the volcano has a rather low viscosity, which allows it to travel down the side of the volcano at a large speed.

By contrast, lava typically produced from volcanic eruptions at a destructive plate boundary is much thicker, and often results in eruptions that have huge pyroclastic flows, including those around much of the Pacific Ring of Fire.

This explains why, although some explosions have occurred during the current Cumbre Vieja eruption, they have been nowhere near as severe as, for example, the 1991 eruption of Mount Pinatubo.

During the 2021 eruption of Cumbre Vieja, the lava flow began at the time of eruption within a day, it had reached a height of 20 feet , and a speed of up to 1,000 feet per hour, destroying everything in its path as it ran down the steep slopes of the volcano.

On October 9th, a new flow emerged as a result of the cinder cone collapsing, reaching speeds of up to 2,300 feet per hour. Some of the flow has been even faster, with eye-witnesses describing a tsunami of lava, flowing as if it were a river of water.

Parts of the lava flow have even reached up to a mile across. The nature of the flow, often erratic and unpredictable due to changes in flow speed and lateral spread, means that it is difficult to predict exactly where it will flow next.

What Are Active Dormant And Extinct Volcanoes

Volcanoes are found in three states extinct, dormant and active. However, there is some disagreement between scientists about the definition of what an extinct, dormant and active volcano is. For most, an active volcano is one that has experienced some activity within the last 10,000 years. The problem with this definition is that a volcano may have erupted some 3000 years ago but is unlikely to erupt again in the future. Others suggest that active volcanoes must be currently displaying some sort of activity, and not limited to eruption. This activity could be the release of gases or frequent seismic activity.

The most active volcano in the world is Kilauea volcano on Hawaii. This is followed by Etna in Italy and Piton de la Fournaise on La Réunion island.

A dormant volcano is said to be one that has not erupted in the last 10 000 years but may erupt again in the future. Some believe that a volcano is dormant, rather than extinct, if there is some record of its past activity.

In comparison, dormant volcanoes have not erupted since the last ice age and are unlikely to erupt again in the future. However, it is very difficult to suggest a volcano will never erupt again in the future. One example of this is Four-Peaked Mountain in Alaska. This volcano was considered to be extinct until 2006, when it began exhibiting signs of activity, and is now classed as dormant.

The image below shows the Kerid Crater, a dormant volcano in Iceland.

Kerid Crater, Iceland.

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Eruption Of Cumbre Vieja

On the 19th September 2021, at 3:12 pm local time, the volcano sprung into life, the first volcanic activity on La Palma in 50 years.

The initial eruption was incredibly forceful, producing huge lava fountains that reached hundreds of feet into the air, and causing giant rivers of molten rock to pour down the western side of the volcano.

Although the Cumbre Vieja eruption has produced numerous explosions, and has discharged ash into the air that has deposited over much of the island, the large lava flows have caused the most destruction.

At the time of writing, lava flows have destroyed 1,400 buildings and displaced around 6,400 people, many of whom live on the western side of La Palma. Roads and other infrastructure lying in the path of the lava flows have also been removed.

The eruption currently shows no signs of stopping, and since the initial eruption in September, several more fissure vents have opened up around the volcano, erupting more molten rock to the surface.

As of mid-October 2021, many scientists have estimated that the eruption could last for a few more months.

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