Volcanoes and Eruptions: Science 7 - 2nd Quarter - Week 2

A set of flashcards covering key vocabulary and concepts related to volcanoes and their eruptions.

Volcano

A depositional mountain landform built from solidified magma from deep within the Earth. An opening in Earth’s crust through which molten rock, rock fragments, and hot gases erupt.

Magma

Molten rock stored underground before it erupts as lava.

Lava

Molten rock that has reached the Earth's surface.

Where do volcanoes occur?

Subduction zones (one plate sinks under another), over hot spots, where plates are pulling apart.

Subduction Zone

An area where one tectonic plate sinks beneath another, often creating volcanoes.

Ring of Fire

A major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur.

Volcanic Ash

A mixture of powder-sized rocks, minerals, and gas particles ejected during a volcanic eruption.

Volcanic Bombs

Rocks and larger debris that are thrown into the air during an eruption.

Ash, steam, and gas

Cloud which is pushed out of the volcano

Crater

Circular depression at the top of the volcano.

Main vent

Main tube that connects the magma chamber to the surface.

Lava

Molten rock after it reaches the surface.

Secondary cone

A cone that builds up around secondary vents.

Secondary vent

A place where magma reaches the surface without going through the main vent.

Magma

Molten rock still underneath the ground.

Magma chamber

Store of underground magma.

Cinder Cone Volcano

The smallest and simplest type of volcano, formed from pyroclastic fragments around the main vent.

Composite Volcano

Also known as a stratovolcano, characterized by alternating layers of lava and tephra, and has acidic and sticky lava.

Composite volcano

Quiet or violent, basaltic or granitic, steep or gentle slopes, and layered of tephra.

Composite volcano

About 2400m (8000ft)

Shield volcano

Formed by quiet eruptions, slow-moving lava flows, basaltic lava builds up in flat layers, and largest with gently sloping slides.

Shield Volcano

A large, broad volcano with gentle slopes, primarily built from low-viscosity basaltic lava.

Active Volcano

A volcano that has erupted during historical times within the last 600 years.

Dormant Volcano

A volcano that is not currently erupting but is expected to erupt again in the future.

Extinct Volcano

A volcano that has not erupted in the last 10,000 years and is not expected to erupt again.

What determines how explosive an eruption is?

Water vapor: more water=bigger explosion

What determines how explosive an eruption is?

Trapped gases (water and CO₂): easy escape (low pressure)=quiet eruption

difficult to escape (high pressure)=explosive/violent eruption

What determines how explosive an eruption is?

Magma type: balastic (thin) =quiet eruption, granite/andestic (thick)=violent eruption

How do scientists monitor volcanoes?

Warning signs: earthquake, changes in the tilt of the ground, rising temperatures of openings, and changes in volcanic gases being tested.

Basaltic or Mafic

A dark colored mafic volcanic rock formed from dried-up iron-filled and magnesium filled lava. It is rich in Fe (iron), Mg, Ca (calcium), but low in K (potassium), and Na(sodium).

Andesitic or Intermediate

Contains an intermediate percentage of Fe (iron), Mg (magnesium), Ca (calcium), K (potassium), and Na (sodium). It has more silicates making it more viscous than basaltic magma.

Rhyolitic or felsic magma

Has the highest amount of silicates and gas content, as well as the highest viscosity among all types of magma.

Explosive Eruption

A type of volcanic eruption characterized by high viscosity magma, resulting in significant gas release and eruption force.

Effusive Eruption

An outpouring of basaltic lava that is relatively low in viscosity and gas content.

Hawaiian eruption

Fluid basaltic lava is thrown into the air, creating a lava fountain or lava flows.

Hawaiian eruption

This creates gentle slopes that form shield volcanoes that usually covers a large area.

Strombolian eruption

There is a burst of glowing lava due to the bursting of gas bubbles and the vents of the volcano.

Vulcanian eruption

Short, explosive, violent. The pressure is enough to blow off the overlying layer of solidified lava over entrapped gases in magma.

Plinian eruption

The most violent volcanic eruptions. It releases huge amounts of gases and ashes at great speeds, it is usually destructive to land and property.

Phreatic Eruption

A steam-driven explosion caused by the interaction of water and hot molten rock.

Phreatomagmatic Eruption

Eruption involving the interaction of magma with external water that produces steam and pyroclastic material.

Volcanic Ash

A mixture or powder-sized rocks, minerals, and gas particles.

Lapilli

“The stones” in Latin. Can range from 4 to 32 mm.

Volcanic blocks

Already solid when ejected during eruptions. More angular because they are not shaped and cooled in like volcanic bombs.