Devin Volcano Flashcards

Questions and Answers

Explain the difference between caldera and crater.

Calderas are generally larger than craters; material comes from a magma chamber for calderas, while material for craters comes out of a vent. Calderas form when the magma chamber roof collapses, whereas craters form when the rim collapses back into the vent.

What is a caldera?

A caldera is formed when a magma chamber that supplies material to a volcano empties and its roof collapses, causing the ground to sink, leaving a large circular depression.

What is a crater?

A crater results from explosions of material out of the vent as well as the collapse of material from the crater's rim back into the vent.

How can ash from a volcanic eruption be hazardous? (Select all that apply)

Smothers and burns crops Signup and view all the answers

Why do cinder cone volcanoes have narrower bases and steeper sides than shield volcanoes?

They are made up of pyroclastic material. Signup and view all the answers

What two factors may cause solid rock to become magma?

An increase in temperature of the rock or a decrease in pressure on the rock. Signup and view all the answers

What is the Ring of Fire?

The Ring of Fire comprises tectonic plate boundaries surrounding the Pacific Ocean. Signup and view all the answers

Why do most volcanoes occur at the boundaries of tectonic plates?

It's easier for the magma to travel upward through the crust. Signup and view all the answers

What type of material does high pressure produce?

Solid. Signup and view all the answers

What type of material does low pressure form?

Liquid. Signup and view all the answers

How is a seismograph used to predict volcanic eruptions?

It detects many small earthquakes that occur before an eruption. Signup and view all the answers

How does a tiltmeter predict volcanic eruptions?

It measures the angle of slope; if it's bulging, magma is pushing against the inside of the volcano. Signup and view all the answers

What is the difference between lava and magma?

Lava is found above ground and comes out of volcanoes, while magma is found deep underground in chambers beneath volcanoes. Signup and view all the answers

What is the difference between lava and pyroclastic material?

Lava flows consist of molten rock, while pyroclastic materials consist of rock fragments and gases. Signup and view all the answers

What is the difference between a cinder cone volcano and a shield volcano?

A shield volcano has enormous, runny lava with non-explosive eruptions, spreading out over a wide area; a cinder cone volcano is small, has moderately explosive eruptions, made of pyroclastic material, with steep slopes and a narrow base. Signup and view all the answers

Name four types of lava.

Pillow Signup and view all the answers

Describe blocky lava.

Blocky lava is cool, stiff, and thick in consistency, barely creeping along the ground. Signup and view all the answers

Describe pahoehoe lava.

Pahoehoe lava flows slowly, forming a glassy surface with rounded wrinkles. Signup and view all the answers

Describe Aa lava.

Aa lava has a jagged surface, pours out quickly, and forms a brittle crust. Signup and view all the answers

Describe pillow lava.

Pillow lava forms when lava erupts underwater, creating rounded lumps that are the size and shape of pillows. Signup and view all the answers

The type of magma that often produces a violent eruption is what?

Thick due to high silica content. Signup and view all the answers

When lava hardens quickly to form ropy formations, it is called what?

Aa. Signup and view all the answers

Volcanic dust & ash can remain in the atmosphere for months or years, causing what?

Decreased solar reflection and lower temperatures. Signup and view all the answers

Mount St. Helens covers the city of Spokane, WA with tons of ash. Its eruption would most likely be described as what?

Explosive, producing lava. Signup and view all the answers

Magma forms within the mantle most often as a result of what?

High temperature and low pressure. Signup and view all the answers

Study Notes

Volcano Definitions and Differences

Caldera: A large circular depression formed by the collapse of the ground after a magma chamber empties.
Crater: A smaller depression that results from explosive material ejection and the collapse of the rim back into the vent.
Comparison: Caldera generally larger than craters; calderas form from magma chamber collapse, while craters form from vent ejecta.

Volcanic Hazards

Ash Hazards: Ash can block sunlight, damage trees and buildings, harm crops by smothering and burning, and cause flooding by plugging rivers.

Types of Volcanoes

Cinder Cone Volcanoes: Have narrower bases and steeper sides; composed of pyroclastic materials leading to their structure.
Shield Volcanoes: Characterized by broad bases and gentle slopes; formed from runny lava with non-explosive eruptions.

Magma Formation

Solid to Magma Transition: Solid rock becomes magma when temperature increases or pressure decreases.

Tectonic Plates and Volcanoes

Ring of Fire: A region of tectonic plate boundaries surrounding the Pacific Ocean, known for high volcanic activity.
Volcano Location: Most volcanoes occur at tectonic plate boundaries where magma can easily travel to the surface.

Pressure and Material States

High Pressure: Leads to solid material.
Low Pressure: Results in liquid material.

Volcanic Prediction Technology

Seismograph: Detects small earthquakes that often occur prior to an eruption, aiding in prediction.
Tiltmeter: Measures slope angle; bulging indicates magma movement within the volcano.

Lava vs. Magma

Magma: Found underground in chambers beneath volcanoes.
Lava: The molten rock that reaches the Earth’s surface.

Lava Types Comparison

Lava vs. Pyroclastic Material: Lava consists of varied molten rock types; pyroclastic includes rock fragments and gases.

Types of Lava

Blocky Lava: Thick and stiff; moves slowly across the ground.
Pahoehoe Lava: Forms a smooth, glassy surface with rounded wrinkles; flows slowly.
Aa Lava: Quick flowing; has a jagged surface and forms a brittle crust.
Pillow Lava: Forms underwater, creating rounded lumps resembling pillows.

Eruption Characteristics

Violent Eruptions: Often produced by thick magma with high silica content.
Explosive Eruptions: Characterized by significant ash production and explosive lava activity.

Environmental Impact

Volcanic Dust: Can linger in the atmosphere for extended periods, causing decreased solar reflection and lower temperatures.
Mount St. Helens Eruption: Described as explosive, impacting regions with a significant ash fall, such as Spokane, WA.

Magma Formation Conditions

Common Process: Most magma forms in the mantle due to high temperatures and low pressure conditions.

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Description

Explore the key concepts of volcanic formations through these flashcards. Learn the differences between calderas and craters, including their definitions and characteristics. Perfect for students studying geology or anyone interested in volcanology.