When a volcano erupts, it spews out hot lava and gases from an opening in the Earth. This can lead to people having to leave their homes quickly because the flowing lava can be dangerous. The most common result is that many people have to move to safer areas to avoid getting hurt by the moving lava.

Types of Volcanic Eruptions

Volcanic activity and volcanic areas are commonly divided into six major types:

• Icelandic volcanoes are known for spewing molten basaltic lava through long, parallel cracks. This often results in the formation of lava plateaus.
• Hawaiian volcanoes share similarities with Icelandic ones. However, in Hawaiian volcanoes, fluid lava flows from the summit and radial cracks, creating large shield volcanoes with gentle slopes.
• Strombolian eruptions involve moderate bursts of expanding gases that release glowing lava clots in cyclical or nearly continuous small explosions. The Stromboli volcano in Italy, situated on Stromboli Island, is nicknamed the “lighthouse of the Mediterranean” due to its frequent, small outbursts.
• Named after Vulcano Island near Stromboli, Vulcanian eruptions involve moderate explosions of gas filled with volcanic ash. These eruptions generate dark, turbulent clouds that swiftly ascend and expand in intricate shapes.
• Pelean eruptions are associated with explosive outbursts, generating pyroclastic flows—dense mixtures of hot volcanic fragments and gas. These flows, heavier than air but with low viscosity, race down valleys and slopes, causing significant destruction.
• Plinian eruptions are intensely violent. Gases escaping from gas-rich magma create massive, continuous jetting blasts that carve out the magma conduit. The resulting eruption clouds resemble a gigantic rocket blast, reaching into the stratosphere and sometimes lasting for several hours.

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Causes of Volcanic Eruption

• The Earth’s mantle is super hot, ranging from 1000 to 3000 degrees Celsius.
• The melted rock, now a light liquid called magma, rises up because it’s lighter than the solid rocks around it. It’s like how wood floats on water.
• This magma mix includes andesitic and rhyolitic stuff, plus dissolved water, sulfur dioxide, and carbon dioxide. Think of it as a bubbly, molten cocktail.
• As the magma gets closer to the surface, bubbles form because of the decreasing pressure. Imagine opening a fizzy soda – bubbles rise, right? Same idea.
• When about 75% of the magma turns into bubbles, it’s like a volcanic party. The magma bursts, breaking into fiery bits called pyroclasts.
• The main reasons for these volcanic outbursts are:
  • Magma’s Weight Watchers: Magma’s buoyancy – it wants to float up because it’s lighter.
  • Gas Pressure Drama: Gases in the magma create pressure, pushing the magma upward. It’s like soda fizzing up in a can.
  • Chamber Lid Issues: Increased pressure on the chamber’s “lid” (the crust) is like trying to contain a soda can that’s about to burst.

How do Volcanoes Eruption?

• Earth’s inner heat causes rocks deep within to slowly melt, forming a thick, flowing substance called magma.
• As magma is lighter than solid rock, it rises and gathers in magma chambers beneath the Earth’s surface.
• Over time, some magma forces its way through cracks and openings in the Earth’s crust.
• A volcanic eruption results in the emergence of molten rock known as lava on the surface.

Now, let’s break down Earth’s structure:

• The outermost layer, called the lithosphere, is at the top. It includes both the upper crust and mantle.
• Silicate rock primarily makes up the Earth’s crust, with thickness ranging from 10km to 100km, especially in mountainous regions.

Why do Volcanoes Eruption?

• The Earth’s mantle, located within the crust, has different sections based on seismology.
• There’s the upper mantle (8 – 35 km to 410 km), the transition zone (400 to 660 km), and the lower mantle (660 – 2891 km).
• As you go deeper into the Earth, the pressure and temperature dramatically increase, reaching up to 1000°C.
• This leads to the formation of viscous and molten rock, collecting in large chambers within the Earth’s crust.
• Magma, being lighter than surrounding rock, rises toward the surface, seeking out cracks and weaknesses in the mantle.
• Eventually, it erupts from the peak of a volcano, spewing ash and molten rock.
• Eruptions build up rocks, lava, and ash around the volcanic vent.
• The type of eruption depends on the viscosity of the magma.
• Flowing magma creates broad shield volcanoes, while thicker magma forms the classic cone shape.
• Extremely thick lava can accumulate in the volcano and explode, creating lava domes.

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Magma vs Lava: The difference

Magma refers to molten rocks and materials beneath the Earth’s surface, often originating from the softer mantle layer known as the asthenosphere. When this molten material emerges through a volcano’s vent, it becomes lava. In simpler terms, lava is essentially magma on the Earth’s surface. The overall process of materials escaping from the Earth’s interior to its surface is termed volcanism.

Volcanic Activity

Volcanoes are often found in areas with significant folding and faulting, commonly along coastal mountains, islands, and in the mid-ocean regions. The interior parts of continents generally experience fewer volcanic activities. The Pacific Ring of Fire, known for its high volcanic activity, hosts the majority of active volcanoes around the world.