Unit 15: Understanding Volcanoes
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Questions and Answers

In 1991, Mount Pinatubo erupted in the Philippines, ejecting 10 km³ of material into the atmosphere. What is the name of the local deity that the Aetas believe lives in the mountain?

Apung Pinatubo

What is the process called in which magma, which is buoyant against rock, rises to the surface and becomes lava?

  • Volcanism (correct)
  • Erosion
  • Tectonics
  • Subduction

What is the term for the process that occurs when volatiles are added to rocks, resulting in melting into magma?

  • Decompression melting
  • Flux melting (correct)
  • Magmatic differentiation
  • Anatexis

What is the name for a region of abnormally high temperature known as a hot spot, which triggers anatexis of the overlying oceanic or continental plate?

<p>Mantle plume (A)</p> Signup and view all the answers

The Hawaiian Islands and the Emperor Seamount Chain represent an example of ocean island basalts.

<p>True (A)</p> Signup and view all the answers

Which volcano classification is NOT characterized by its shape?

<p>Active volcanoes (A)</p> Signup and view all the answers

Lava dome mounds are roughly circular. These domes form when ______ lava cannot flow too far due to the viscosity and cools into a mound.

<p>viscous</p> Signup and view all the answers

Shield volcanoes are broad, gently sloping mounds shaped like a ______

<p>soldier's shield</p> Signup and view all the answers

What is the name for the layer of solidified volcanic material that forms around a conduit?

<p>Mound (B)</p> Signup and view all the answers

Composite volcanoes, also known as stratovolcanoes, are tall, steep, ______ mountains.

<p>conical</p> Signup and view all the answers

What are the smaller, steeper mounds composed of tephra, which represent the remnants of explosive eruptions, called?

<p>Pyroclastic cones (A)</p> Signup and view all the answers

Which of the following is NOT considered a type of eruption?

<p>Volcanoclastic (C)</p> Signup and view all the answers

What is the name given to the small, steep mounds composed of tephra or volcanic fragments formed by explosive eruptions?

<p>Pyroclastic cones (B)</p> Signup and view all the answers

What type of eruption produces lava flows exclusively, typically involving low-viscosity lavas?

<p>Effusive (B)</p> Signup and view all the answers

Which of the following is the primary cause of explosive eruptions?

<p>The increase of dissolved gases in the magma (D)</p> Signup and view all the answers

Which eruption type usually occurs in a shallow body of water, producing strong explosions as a result of magma coming into contact with water?

<p>Surtseyan (D)</p> Signup and view all the answers

Which type of eruption results from the extreme buildup of gases in the magma chamber, leading to a column of debris and ash that can reach more than 10 km high?

<p>Plinian (C)</p> Signup and view all the answers

Which eruption type results from the collapse of the eruption column into an incandescent pyroclastic flow?

<p>Pelean (B)</p> Signup and view all the answers

Which eruption type originates from viscous lava which slows down bubble formation and clogs up conduits, leading to build-up of pressure that causes an eruption column of 5-10 km?

<p>Vulcanian (A)</p> Signup and view all the answers

Which eruption type is characterized by sustained fissure eruptions, which produce curtains of basaltic lava, and often result in the formation large igneous provinces?

<p>Icelandic (C)</p> Signup and view all the answers

Which type of eruption is characterized by the bursting of clumps of gas bubbles at the surface, resulting in incandescent lava flows and pyroclastic debris, with an eruption column less than 5 km high?

<p>Strombolian (D)</p> Signup and view all the answers

The eruption of Mount Vesuvius, which destroyed Pompeii and Herculaneum, is an example of a Vulcanian eruption.

<p>False (B)</p> Signup and view all the answers

Which type of eruption is characterized by the violent thermal contraction of magma as it interacts with water, resulting in an explosion?

<p>Phreatomagmatic (C)</p> Signup and view all the answers

Which type of eruption is driven purely by steam generated in a volcanic source?

<p>Phreatic (C)</p> Signup and view all the answers

The type of eruption a volcano experiences is dependent on its size and shape.

<p>False (B)</p> Signup and view all the answers

What are the primary products of volcanic eruptions, which consist of molten rock materials that have risen to the surface?

<p>Lavas (B)</p> Signup and view all the answers

Volcanic glass is a type of volcanic rock that forms when lava cools quickly, preventing crystal formation.

<p>True (A)</p> Signup and view all the answers

What is the name given to the elongated, rod-like features that are formed as lava flows solidify, perpendicular to the direction of flow, creating hexagonal patterns?

<p>Columnar jointing (A)</p> Signup and view all the answers

Which type of lava produces the wrinkled, billowing, or ropey surface texture characteristic of pahoehoe flows?

<p>Basaltic (A)</p> Signup and view all the answers

What is the name given to the rough, broken, and rubble-like surface texture characteristic of aʼaʻ flows?

<p>Aʼaʻ (C)</p> Signup and view all the answers

When basaltic lava flows rapidly underwater, it is squeezed into blobs, called ______ lavas.

<p>pillow</p> Signup and view all the answers

What type of volcanic flow is characterized by high viscosity and tends to form mounds rather than flowing far distances?

<p>Andesitic (A)</p> Signup and view all the answers

What type of volcanic flow is known for its low viscosity and often forms lava domes?

<p>Rhyolitic (C)</p> Signup and view all the answers

What type of volcanic flow is characterized by its extreme viscosity, which makes it flow slowly and often forms domes?

<p>Rhyolitic (C)</p> Signup and view all the answers

The term "volcanoclastic deposit" refers exclusively to the fragments of lava that have been ejected from a volcano during an eruption.

<p>False (B)</p> Signup and view all the answers

What is the name given to the solid, solidified volcanic fragments that are ejected from a volcano, typically during explosive eruptions?

<p>Pyroclastic debris (C)</p> Signup and view all the answers

What is the name for the solid, frothy, mafic tuff that forms from the cooling of volcanic ash and lapilli, often with a bubbly appearance?

<p>Scoria (C)</p> Signup and view all the answers

What is the name for the welded tuff, a solidified and cemented deposit of volcanic ash that is formed by the heat of a pyroclastic flow?

<p>Ignimbrite (B)</p> Signup and view all the answers

Lahars are a type of volcanic flow that occurs when volcanic ash mixes with enough water to form a viscous slurry.

<p>True (A)</p> Signup and view all the answers

What are the gases that are released from magma during volcanic eruptions, which can range from water vapor to carbon dioxide and hydrogen sulfide?

<p>Volatiles (A)</p> Signup and view all the answers

Volatiles are essential for driving the majority of explosive eruptions as they create pressure build-up that is released through the explosion.

<p>True (A)</p> Signup and view all the answers

What is the primary source of geothermal energy?

<p>The Earth's internal heat (A)</p> Signup and view all the answers

What is the area where groundwater transfers heat from a source to a heat sink, serving as the basis for exploitation of geothermal energy?

<p>Geothermal system (A)</p> Signup and view all the answers

What is the name given to the hot, mineralized fluids that are found in geothermal reservoirs?

<p>Geothermal fluid (B)</p> Signup and view all the answers

What is the term used to describe the wells that are drilled into the geothermal reservoir for extracting hot fluids?

<p>Production wells (C)</p> Signup and view all the answers

What is the term for the process of injecting cold water back into the ground to replenish the geothermal reservoir after extraction of hot fluids?

<p>Re-injection (C)</p> Signup and view all the answers

Geothermal energy is renewable, sustainable, and generally considered environmentally friendly.

<p>True (A)</p> Signup and view all the answers

The Philippines, being a country with active volcanoes, has a significant geothermal resource potential, which is why it is one of the leading producers of geothermal energy in the world.

<p>True (A)</p> Signup and view all the answers

The Philippines has built a large number of geothermal power plants, utilizing its geothermal resource base.

<p>True (A)</p> Signup and view all the answers

What is the name of the largest geothermal power plant in the Philippines, located in Tongonan, Leyte?

<p>Tongonan Geothermal Power Plant (A)</p> Signup and view all the answers

Which of the following is a consequence of using geothermal energy that can pose environmental risks?

<p>Release of greenhouse gases (A)</p> Signup and view all the answers

A volcanic ______ is any vent or built-up mountain where lava, pyroclastic materials, or gases erupt.

<p>vent</p> Signup and view all the answers

Divergent boundaries occurring between two oceanic plates are known as ______ volcanoes.

<p>oceanic</p> Signup and view all the answers

Arcs growing on continents are known by this term: ______.

<p>continental arcs</p> Signup and view all the answers

The region of abnormally high temperature created by intraplate volcanism is known as a ______.

<p>hot spot</p> Signup and view all the answers

Many successive flood basalt eruptions can form a ______ of lava flows.

<p>plateau</p> Signup and view all the answers

At divergent boundaries, volcanism manifests as ridges or fissures where lavas erupt and produce ______ melting.

<p>flux</p> Signup and view all the answers

The suite of magmas typically produced at convergent boundaries is known for being highly ______.

<p>explosive</p> Signup and view all the answers

______ volcanism creates a series of eruptions that are characterized by the outpouring of large amounts of lava.

<p>Intraplate</p> Signup and view all the answers

Lava that is silica-depleted and has a low viscosity is called ______.

<p>basaltic</p> Signup and view all the answers

The volcanic flows characterized by an intermediate viscosity and forming mounds are known as ______.

<p>andesitic</p> Signup and view all the answers

The most silica-enriched volcanic flows are referred to as ______ flows.

<p>rhyolitic</p> Signup and view all the answers

Lava tubes are conduits within flows that allow the interior to remain hot and ______.

<p>molten</p> Signup and view all the answers

Pahoehoe is a type of lava flow that has a ______ surface texture.

<p>low-viscosity</p> Signup and view all the answers

When basaltic lava flows underwater, it is shaped into blobs known as ______ lavas.

<p>pillow</p> Signup and view all the answers

The unique structure formed from the cooling and contraction of lava into hexagonal columns is called ______.

<p>columnar jointing</p> Signup and view all the answers

As pahoehoe cools and increases in viscosity, it can evolve into ______ flow.

<p>a’a’</p> Signup and view all the answers

Magma accumulates underground in an open space known as a ______ vent.

<p>flank</p> Signup and view all the answers

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) monitors volcanic hazards in the ______.

<p>Philippines</p> Signup and view all the answers

Low-viscosity lava can form ______ volcanoes, which are broad and gently sloping.

<p>shield</p> Signup and view all the answers

The need to classify volcanoes is essential for assessing ______ risks.

<p>hazard</p> Signup and view all the answers

Multiple pyroclastic cones can form from one eruptive ______.

<p>event</p> Signup and view all the answers

In the case of lava flows, viscosity refers to the ______ of the lava.

<p>thickness</p> Signup and view all the answers

Lahars form when volcanic ash mixes with enough ______ to create a slurry.

<p>water</p> Signup and view all the answers

The process in which magma rises to the surface and becomes ______ is known as volcanism.

<p>lava</p> Signup and view all the answers

The eruption of Mount Pinatubo in 1991 is an example of a significant ______ event.

<p>volcanic</p> Signup and view all the answers

At divergent boundaries, volcanism manifests as ridges or ______ where lavas erupt.

<p>fissures</p> Signup and view all the answers

Divergent boundaries mostly occur between two ______ plates.

<p>oceanic</p> Signup and view all the answers

Volcanism at mid-ocean ridges accounts for the production of new oceanic ______.

<p>crust</p> Signup and view all the answers

Decompression melting occurs when portions of Earth's mantle move to an area of lower ______.

<p>pressure</p> Signup and view all the answers

Most eruptions occur along plate ______, while some occur at intraplate hot spots.

<p>boundaries</p> Signup and view all the answers

Volcanism is influenced by plate interactions at their ______.

<p>boundaries</p> Signup and view all the answers

Magma becomes ______ when it rises and erupts through a volcano.

<p>lava</p> Signup and view all the answers

__________ eruptions are sustained fissure eruptions, producing curtains of basaltic lava.

<p>Icelandic</p> Signup and view all the answers

__________ eruptions produce low-viscosity basaltic lava flows and fountains.

<p>Strombolian</p> Signup and view all the answers

__________ eruptions are the result of the bursting of clumps of gas bubbles at the surface.

<p>Vulcanian</p> Signup and view all the answers

__________ eruptions result from more viscous lava, which slows down bubble formation and clogs up conduits.

<p>Plinian</p> Signup and view all the answers

__________ eruptions result from the extreme buildup of gases in the magma chamber and conduit.

<p>Phreatomagmatic</p> Signup and view all the answers

__________ are purely steam-driven, caused by the expansion of water into steam when heated by a nearby magma chamber or volcanic source.

<p>Phreatic eruptions</p> Signup and view all the answers

Over time, Hawaiian eruptions produce __________ volcanoes.

<p>shield</p> Signup and view all the answers

Prolonged Icelandic eruptions produce __________.

<p>large igneous provinces</p> Signup and view all the answers

Plinian eruptions result from the extreme buildup of gases in the magma chamber and conduit, which become as much as ______% gas.

<p>75</p> Signup and view all the answers

Peléan eruptions are characterized by nuée ardente or 'glowing ______,' which result from the collapse of the eruption column.

<p>avalanches</p> Signup and view all the answers

Vulcanian eruptions result from more viscous lava, which slows down bubble formation and clogs up ______.

<p>conduits</p> Signup and view all the answers

Strombolian eruptions result from the bursting of clumps of gas bubbles at the surface, throwing up clots of ______.

<p>lava</p> Signup and view all the answers

Hawaiian eruptions produce low-viscosity basaltic lava flows and ______.

<p>fountains</p> Signup and view all the answers

A Surtseyan eruption occurs in a shallow body of water, characterized by strong ______ as magma comes in contact with water.

<p>explosions</p> Signup and view all the answers

Phreatomagmatic eruptions are driven by the violent thermal contraction of magma when it interacts with ______.

<p>water</p> Signup and view all the answers

Icelandic eruptions produce curtains of basaltic ______.

<p>lava</p> Signup and view all the answers

Flashcards

Volcanism

The process by which magma rises to the surface and becomes lava.

Volcano

A vent or built-up mountain where lava, pyroclastic materials, and/or gases erupt.

Decompression melting

The process where portions of Earth's mantle move to an area of lower pressure, resulting in melting of rocks into magma.

Anatexis

Partial melting of rocks due to decreased lithostatic pressure.

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Lava

Magma that has erupted onto the surface.

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Mid-ocean ridges

Elongated volcanic chains parallel and proximal to the plate boundary, or ridge axis.

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Continental rifts

Divergent boundaries occurring within continental plates.

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Flux melting

Melting of rocks due to the addition of substances like volatiles and water.

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Arcs

Curving volcanic chains that follow the shape of trenches.

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Island arcs

Arcs growing on the oceanic crust.

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Continental volcanic arcs

Arcs growing on continents.

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Hot spot

A region of abnormally high temperature caused by the ascent of mantle plumes to the base of the lithosphere.

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Hot spot volcanic chains

Chains of extinct volcanoes formed by hot spot volcanism.

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Flood basalts

Massive sheets of lava flows.

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Large igneous provinces (LIPs)

Plateaus of lava flows formed by many successive flood basalt eruptions.

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Magma chamber

The accumulation of magma underground in an open space.

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Conduits

Openings through which magma rises to the surface.

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Dikes

Rock sheets that form from magma seeping into cracks in rocks.

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Sills

Beds of rocks that form between layers of older materials.

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Crater

The end of a pipe-like conduit at the top of a volcanic mound.

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Flank vent

Smaller conduits issuing from a central vent.

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Fissure

Elongated cracks through which magma erupts.

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Caldera

Large circular depression with steep walls formed by the collapse of a volcanic mound.

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Lava domes

Roughly circular mounds formed when viscous lava cools into a mound.

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Shield volcanoes

Broad gently-sloping mounds shaped like a shield.

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Composite Volcanoes/Stratovolcanoes

Tall, steep, conical mountains formed by the accumulation of various erupted materials.

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Pyroclastic cones

Small, steep mounds composed of tephra or volcanic fragments formed by explosive eruptions.

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Cinders/Lapilli

Lava fragments 2-64 mm in size.

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Blocks

Large (>64 mm) angular fragments tore off the volcano or blasted apart by the explosion.

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Ash

The finest fragments of volcanic debris.

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Cinders/Lapilli

Drops and clumps of lava ejected into the air by a volcanic eruption.

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Pele's tears

Glass droplets formed from lava during flight.

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Pele's hair

Glass filaments formed from lava during flight.

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Spatter

Blobs of spatter ejected by lava fountains.

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Spatter cones/ramparts

Cones and ramparts built from accumulated spatter.

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What is Volcanism?

The process in which magma, which is buoyant against rock, rises to the surface and becomes lava.

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What is a Volcano?

Any vent or built-up mountain where lava, pyroclastic materials, and/or gases erupt.

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Where do Mid-Ocean Ridges occur?

Divergent boundaries mostly occur between two oceanic plates, and the volcanism at these boundaries manifest as mid-ocean ridges.

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Why are volcanic locations important?

The location where volcanism occurs largely dictates the types of magma generated, and thus the style of volcanism.

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What is Decompression melting?

The process where portions of Earth's mantle move to an area of lower pressure, resulting in melting of rocks into magma.

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What is Anatexis?

Partial melting of rocks due to decreased lithostatic pressure.

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Where does volcanism occur at divergent boundaries?

At divergent boundaries, volcanism manifests as ridges or fissures where lavas erupt.

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How do rocks melt due to pressure change?

Rocks start to melt even with low temperature due to difference in pressures.

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Effusive eruption

A volcanic eruption where lava flows smoothly from the volcano's vent.

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Explosive eruption

A volcanic eruption characterized by the explosive release of volcanic materials, often accompanied by ash clouds and debris.

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Magmatic eruption

A type of volcanic eruption driven by the pressure of expanding gases within the magma.

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Icelandic eruption

Sustained fissure eruptions, where lava flows out like a curtain from a crack in the Earth.

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Plinian eruption

A violent volcanic eruption in which massive amounts of ash and volcanic debris are expelled, forming a towering eruption column.

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Strombolian eruption

A type of volcanic eruption characterized by the ejection of glowing fragments of incandescent lava and gas.

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Vulcanian eruption

A type of volcanic eruption characterized by bursts of incandescent lava and gas, often making intense 'boom' sounds.

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What is a caldera?

A large, circular depression formed by the collapse of a volcanic mound after a major eruption.

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What is a flank vent?

Magma accumulates underground in a large, open space or a highly fractured area, typically beneath the surface.

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Phreatic eruption

A volcanic eruption that occurs when groundwater is heated by magma, causing it to flash into steam and explosively erupt.

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Why is it important to classify volcanoes?

Volcanoes are classified to help scientists better understand their behavior and potential hazards.

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What is an active volcano?

A volcano that has erupted in the past and is likely to erupt again.

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What is an inactive volcano?

A volcano that has not erupted in recorded history and is considered unlikely to erupt again.

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What is PHIVOLCS?

The Philippine Institute of Volcanology and Seismology (PHIVOLCS) is responsible for monitoring and providing warning systems for volcanic hazards in the Philippines.

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Mid-ocean ridge volcanoes

Volcanoes located at divergent boundaries between two oceanic plates. They are characterized by their relatively gentle slopes and the eruption of basalt lava, often creating mid-ocean ridges.

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Continental hot spots

Regions where mantle plumes rise to the base of the lithosphere, causing abnormally high temperatures. These regions are characterized by their volcanic activity, often resulting in the formation of island chains or large volcanic provinces.

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Continental rift volcanoes

Volcanoes formed at divergent boundaries within continental plates. They are associated with the process of continental rifting, where the crust is being pulled apart, leading to volcanic activity.

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Calcalkaline magmas

A suite of magmas typically produced at convergent plate boundaries. These magmas are characterized by their high silica content and their explosive nature.

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Viscosity of Lava

The resistance of a fluid to flow. In the context of lava, it refers to the ease with which lava can move. High viscosity means the lava is thick and slow-moving, while low viscosity means the lava is runny and fast-moving.

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Pahoehoe Lava Flow

A type of lava flow characterized by low viscosity, smooth, billowing, or ropey surfaces. Typically formed from basaltic lava.

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A'a' Lava Flow

A type of lava flow characterized by high viscosity, broken, rubbly, or spiny surfaces. Typically formed from basaltic lava that has cooled and become more viscous.

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Andesitic Lava Flow

A type of lava flow characterized by intermediate viscosity, forming slow-moving mounds with large, angular blocks. It is associated with andesitic lava.

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Rhyolitic Lava Flow

A type of lava flow characterized by very high viscosity and a blocky, bulbous mass. It is associated with rhyolitic lava and often forms lava domes.

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Columnar Jointing

Regularly spaced, hexagonal columns formed perpendicular to the direction of a lava flow as it cools and contracts. They are commonly observed in basalt flows.

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Pillow Lavas

Round blobs of lava that form underwater due to rapid cooling and water pressure. They are characteristic of basaltic lava flows.

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Hawaiian Eruption

A type of eruption characterized by effusive lava flows and fountains, producing shield volcanoes over time.

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Surtseyan Eruption

An explosive volcanic eruption where magma interacts with water, resulting in strong explosions and ash ejection.

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Peléan Eruption

A volcanic eruption similar to Vulcanian eruptions, but with a larger volume of ejected material and frequent glowing avalanches (nuée ardente).

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Phreatomagmatic Eruption

An explosive eruption driven by the interaction of magma and water, resulting in fast and violent explosions.

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Study Notes

Unit 15: Understanding Volcanoes

  • Volcanoes are openings in the Earth's surface from which lava, gases, and pyroclastic materials erupt.
  • Volcanism is the process by which magma rises to the surface.
  • Volcanoes form in different settings like divergent boundaries, convergent boundaries, and hotspots.
  • They are classified based on their structure and activity.
  • Different types of volcanoes include shield volcanoes, composite volcanoes, cinder cones, and lava domes.
  • Volcanic eruptions produce various materials like lava, ash, tephra, and gases; these can be cinders or lapilli.
  • Eruptions can be classified as effusive or explosive based on the type of material erupted and its explosiveness; different styles exist like Hawaiian, Strombolian, Plinian, and Peléan.
  • The geothermal gradient is the rate of temperature increase with depth beneath the Earth's surface, typically around 30°C per kilometer.
  • Geothermal energy can be harnessed from volcanic areas for human use; power plants use the heat to generate electricity.
  • PHIVOLCS (Philippine Institute of Volcanology and Seismology) monitors volcanic activity in the Philippines; the organization uses a classification system for volcanoes, focusing on those with a higher risk of eruption.
  • The Philippines is in a geologically active area, meaning there are many volcanoes, located in the “Ring of Fire”.
  • The classification system for volcanoes helps identify areas with higher risk potential, enabling better preparedness for volcanic hazards.
  • Volcanic eruptions can produce different types of debris like pyroclastic flows, and ash blankets, which can solidify into tuff, ignimbrite, or other materials.
  • Different volcanic eruptions have distinctly different results with varied compositions and viscosity.

Essential Questions

  • Volcanoes are important in understanding Earth's processes and in maintaining the Earth's internal energy balance.
  • Understanding volcanoes helps us better prepare for volcanic hazards and harness volcanic energy for human use; this includes managing associated risks and developing strategies that utilize the energy for human benefit.

Review

  • Plate tectonics theory states that Earth's lithosphere is broken into plates, and their interactions at the boundaries lead to different processes and landforms.
  • Plate boundaries include divergent, convergent, and transform boundaries.
  • Magma is molten rock material; lava is magma on the Earth's surface.
  • Volcanic activity is linked to plate tectonics; understanding these forces is essential to understand volcanic processes.

Lesson 15.1: Volcanoes

  • Volcanoes form when magma rises to the surface and erupts; the process is driven by various factors including degassing, pressure, and changes in the geothermal gradient.
  • Understanding geological processes like plate tectonics helps to understand the cause of eruptions.
  • An activity, "Volcano in a Beaker," can demonstrate how eruptions might occur; this can illustrate the interplay of heat, pressure, and the release of gases within a model eruption.

Lesson 15.2: Types of Volcanoes Based on Structure

  • There are different types of mounds that volcanoes can form with varying shapes and heights; these are often based on viscosity, composition, and eruptive style.
  • This activity illustrates differences in the shape, height, and slope of various volcano types using clay and illustration board; this visual representation allows for better comprehension of the different structural characteristics of volcanoes.

Lesson 15.3: Active and Inactive Volcanoes

  • Active volcanoes have eruptive histories, meaning there's been a recorded eruption.
  • Potentially active volcanoes, while not having recent recorded eruptions, exhibit features indicating history of volcanic activity.
  • Inactive volcanoes have no eruptive history and will not erupt again.
  • The Philippines has 23 active volcanoes and is identified as a region in the Ring of Fire, which places the country in a geologically active area.
  • Different volcanoes exhibit different types of eruptions; monitoring activity and classifying types can better assist in understanding and managing risk.

Lesson 15.4: Volcanic Eruptions

  • Volcanic eruptions can be classified based on their eruptive style, explosivity, the volume of debris, and the height of the resulting column; using the Volcanic Explosivity Index (VEI) better categorizes volcanic events.
  • Eruptions can be effusive (lava flows) or explosive (pyroclastic flows), leading to vastly differing types and impacts.
  • Magmatic eruptions, phreatic eruptions, or phreatomagmatic eruptions are driven by different, often interacting, processes.

Lesson 15.5: Materials Emitted from Volcanic Eruptions

  • Primary volcanic products are lava and pyroclastic materials.
  • Lava can be basaltic, rhyolitic, or andesitic, and its viscosity influences its flow characteristics.
  • Pyroclastic materials are fragments of rock and lava ejected during an eruption. These can include different materials (ash, cinders, lapilli) and in different forms like glass or blocks.
  • The different materials, whether lava or pyroclastic fragments, exhibit variations in their properties based on a variety of factors like structure, composition, and origin; this can result in diverse forms and impacts.

Lesson 15.6: Harnessing Volcanic Energy

  • Geothermal energy is the internal heat of the Earth.
  • Volcanoes are often situated in areas of high geothermal gradients.
  • Geothermal areas and power plants use the heat to generate electricity or to heat buildings.
  • Geothermal resources are renewable, relatively safe, and cheap but can have environmental consequences like water contamination or subsidence.
  • The different types of volcanic materials and structures are tied to the different types and properties of the geothermal fluids.

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Explore the fascinating world of volcanoes in Unit 15. This quiz covers volcanic formations, eruptive processes, and the various types of volcanoes. Test your understanding of volcanism and its impact on the Earth's landscape.

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