Studied by 45 peopleWhat is a volcano?
An erupting vent through which molten rock surfaces
What happened in 79 C.E. at Mount Vesuvius?
Pyroclastic flows destroyed Pompeii, killing 20,000.
What are the three forms of volcanic products mentioned on page 6?
Lava flows, pyroclastic debris, volcanic gases
What factors determine the viscosity of lava?
Composition, especially silica (SiO2), Fe, and Mg content, temperature, gas content, crystal content.
What is the characteristic of mafic lava?
Very hot, low silica, and low viscosity
What is a lava tube?
A conduit—a lava tube—develops in the flow.
What is the term for basalt with a glassy, ropy texture?
Pahoehoe
What is the characteristic of andesitic lava flows?
They remain close to the vent.
What are examples of volcaniclastic deposits?
Pyroclastic debris, preexisting rock, landslide debris
What is the characteristic of a Stratovolcano (composite volcano)?
Cone-shaped with steeper slopes
What type of volcano is Mauna Loa on Hawaii?
Shield volcano
What is the smallest type of volcano?
Cinder cone
What eruptive style is characterized by regular "burps" of magma, such as seen in Stromboli?
Strombolian eruption
Which volcanic eruption style is associated with huge explosive eruptions that eject massive quantities of material?
Plinian eruption
What are supervolcanoes, and where is an example located?
Large volcanic depressions with massive eruptions; Yellowstone National Park
What significant event happened during the eruption of Mt. St. Helens on May 18, 1980?
The entire north side of the mountain was torn off.
What is the primary gas released during volcanic eruptions?
Water (H20)
How can volcanic eruptions affect climate?
By blocking sunlight with ash and aerosols
Why have humans historically settled in volcanic areas despite the associated risks?
Fertile Soils
What are warning signs that indicate an eruption is imminent?
Changes in shape, emission increases, earthquakes
What is the primary danger associated with lava flows?
Extreme heat
What is a pyroclastic flow, and why is it so destructive?
A flow of superheated ash clouds; it moves extremely fast and incinerates everything in its path.
What type of volcanic material can cause roof collapses due to its weight?
Tuff
In terms of volcanic hazards, what is a lateral blast?
Explosions ejected sideways
What can trigger landslides during volcanic eruptions?
Earthquakes
What is a lahar, and why is it so destructive?
A mudflow resulting from water mixing with ash; it can carry away everything in its path.
How do volcanic eruptions contribute to the formation of earthquakes?
By moving magma
What is a significant impact of volcanic eruptions on the atmosphere?
Blocking sunlight with ash and aerosols
How do volcanic eruptions alter climate on a global scale?
By blocking sunlight and causing atmospheric cooling
What is the purpose of danger assessment maps in volcanic areas?
To delineate danger areas for various hazards like pyroclastic flows and lahars
How can eruptions be diverted, particularly lava flows?
By using explosives, heavy equipment, or seawater
What is the historical significance of the eruption of Mt. Tambora in 1815?
It triggered a volcanic winter and atmospheric cooling.
How do volcanoes impact human societies positively?
By providing fertile volcanic soils suitable for agriculture
What is the term used to describe volcanoes that are not currently erupting but have erupted in the past 10,000 years?
Active
How does volcanic activity influence the formation of lunar maria (dark "seas")?
By generating lava flows
What is a shield volcano, and what type of lava does it primarily erupt?
A broad, slightly dome-shaped volcano erupting low-viscosity basaltic lava
What type of volcano is Mt. St. Helens, and what style of eruption did it experience in 1980?
Composite volcano; explosive eruption
What is the primary reason behind volcanic eruptions at convergent boundaries?Partial melting of the mantle
Partial melting of the mantle
Where do volcanic types like shield volcanoes, cinder cones, and stratovolcanoes form in relation to tectonic settings?
Convergent boundaries
What type of eruption is Stromboli known for, and how does it manifest?
Vulcanian eruption; moderate explosions every 10 to 20 minutes
What volcanic phenomenon is associated with Plinian eruptions, and what is the primary characteristic of these eruptions?
Pyroclastic flows; hot ash clouds moving downslope
How does volcanic activity contribute to the formation of flood basalts?
By intersecting a hot spot with a continental plate
What is the characteristic feature of a caldera, and how does it form?
Gigantic volcanic depression formed by the collapse of a magma chamber
What volcanic type is Mauna Loa on Hawaii an example of, and what lava type does it primarily erupt?
Shield volcano; basaltic lava
What is the primary reason behind volcanic eruptions at mid-ocean ridges?
Decompressional melting
How do volcanic gases, such as sulfur dioxide (SO2), contribute to eruption violence?
By reacting with water to form aerosol sulfuric acid
What type of volcanic deposit is formed by pyroclastic debris that freezes in the air?
Lapilli
How do lava tubes contribute to the long-distance flow of basaltic lava?
By preventing cooling, facilitating flow for miles
What type of volcanic deposit is formed by pyroclastic debris that freezes in the air.
Lapilli
How do lava tubes contribute to the long-distance flow of basaltic lava?
By preventing cooling, facilitating flow for miles
What is the primary hazard associated with lahars?
Mudflows of ash and blocks
What is the primary gas emitted during volcanic eruptions, and which volcano is known for emitting this gas with a rotten-egg smell?
Sulfur dioxide (SO2); Yellowstone
What volcanic feature is created when solidified lava contracts, forming hexagonal fractures?
Columnar jointing
What is the primary factor that determines the flow style of lava, according to page 7?
Viscosity, dependent on composition, temperature, and gas content
Which type of lava is described as having a glassy, ropy texture, and what is the Hawaiian term for it?
Pahoehoe; thin and runny
What is the primary component of volcaniclastic deposits that includes frozen lava fragments?
Ignimbrite
What volcanic hazard is described as an avalanche of hot ash that can move up to 300 km per hour?
Pyroclastic flow
Which volcanic eruption style is characterized by regular "burps" of magma, as exemplified by Stromboli?
Strombolian
What type of eruption is described as moderately sized and explosive, named after an island?
Vulcanian
Which volcanic eruption style is known for huge explosive events, ejecting massive quantities of material?
Plinian
What is the primary gas expelled during volcanic eruptions, and which of the following does it not contribute to?
Water (H2O); lapilli formation
What type of volcano is characterized by broad, slightly dome-shaped structures constructed by the lateral flow of low-viscosity basaltic lava?
Shield volcano
Among the following volcanic types, which is the smallest and consists of conical piles of tephra?
Cinder Cone
What volcanic hazard is characterized by mudflows resulting from water mixing with volcanic ash, and which historical event is associated with a devastating example of this hazard in Colombia?
Lahar; Nevado del Ruiz
Which volcanic eruption style is associated with a plume erupting in shallow seawater, creating steam and carrying ash out of the water?
Surtseyan
What is the term for the phenomenon when volcanic gases react with water to form aerosol sulfuric acid, and which eruption style is most influenced by gas escape style?
Style of gas escape; explosive eruptions
Which volcanic type is characterized by alternating layers of lava, tephra, and debris, often with steeper slopes?
Stratovolcano (Composite volcano)
What volcanic feature is described as a gigantic depression larger than a crater, formed when a magma chamber empties and the volcano collapses?
Caldera
Which volcanic gas is the most abundant, and which one has a rotten-egg smell?
Carbon dioxide (CO2); sulfur dioxide (SO2)
What volcanic feature is created when hot lava skins over, and the exterior crust cracks and breaks into fragments, especially when the lava quenches in water?
Hyaloclastite
Which lava flow style is described as having a glassy, ropy texture and is associated with extremely hot basalt forming a skin that is rolled into ropy ridges and furrows?
Pahoehoe
What type of lava is very hot, with low silica and low viscosity, often facilitating long-distance flow through lava tubes?
Mafic
In what volcanic deposit category do lapilli, Pele's tears, Pele's hair, blocks, and bombs belong?
Tephra fall
Which eruption style is described as regular "burps" of magma, and what volcanic feature is an example of this style on Stromboli Island
Strombolian; Stromboli
What is the primary reason volcanic soils are highly fertile, and which ancient civilization is mentioned as an example of both prosperity and destruction due to volcanic activity?
Rich in minerals; Minoans
What type of volcano is Mauna Loa on Hawaii, and what is its characteristic shape?
Shield volcano; broad and slightly dome-shaped
What is the term for the average time between volcanic eruptions, and what conditions can lead to a volcano being considered "extinct"?
Extinct; not capable of erupting
What is the primary reason volcanic soils are highly fertile, and which ancient civilization is mentioned as an example of both prosperity and destruction due to volcanic activity
Rich in minerals; Minoans
Which volcanic architecture feature is described as a bowl-shaped depression atop a volcano, and what causes craters to form?
Crater; erupted lava piling up around the vent
What is the primary difference between shield volcanoes and stratovolcanoes in terms of magma viscosity and eruption style?
Stratovolcanoes have lower viscosity and effusive eruptions.
Which volcanic feature is associated with a gigantic volcanic depression, often larger than a crater, and what causes the formation of calderas?
Caldera; collapse of a volcano after a massive eruption
What is the primary difference between shield volcanoes and stratovolcanoes in terms of magma viscosity and eruption style?
Shield volcanoes have lower viscosity and effusive eruptions.
Which volcanic feature is associated with a gigantic volcanic depression, often larger than a crater, and what causes the formation of calderas?
Caldera; collapse of a volcano after a massive eruption
What volcanic hazard involves wetted debris moving downhill, often triggered by abundant rain, and where does it typically occur?
Volcanic debris flow; on shield volcanoes
What volcanic hazard is a water-rich debris flow of ash and blocks, and what is its speed and destructive potential?
Lahar; fast and extremely destructive
What volcanic hazard is rarely observed due to explosions ejected sideways, and which famous eruption is an example of this hazard?
Lateral blast; Mt. St. Helens
What volcanic hazard can result from the moving magma causing earthquakes, and what is the potential consequence of island arc eruptions in terms of waves?
Tsunamis; eruption of supervolcanoes
How can volcanic gases, such as sulfur dioxide, impact the atmosphere, and what is the main volcanic gas released during eruptions?
Cause acid rain; sulfur dioxide
What volcanic architecture feature is described as a region of flood basalts on the Moon, and what is the term for the dark "seas" on the lunar surface?
Lunar mare; dark maria
What is the average time between eruptions called, and what are the stages in which volcanoes can be classified based on their activity?
Recurrence interval; erupting, dormant, extinct
What warning signs can indicate an imminent eruption, and why is it challenging to predict the exact timing and style of eruptions based on these signs?
Earthquake activity, changes in shape, emission increases; unpredictability
How can volcanic hazards be mitigated through planning, and what are danger assessment maps used for?
By delineating danger areas; planning and zoning
In which scenario did timely evacuation save lives during a volcanic eruption, and why might evacuation efforts sometimes be met with skepticism?
Mt. St. Helens; due to a lateral blast
What type of lava flow is primarily associated with basalt, and how does it affect the surrounding landscape?
Pahoehoe; ropy texture, creating ridges and furrows
Describe the process of columnar jointing and the significance of this feature in volcanic geology.
Solidification of lava flows; development of hexagonal fractures
What are Pele's tears and Pele's hair, and in which type of eruption are these volcanic features commonly found?
Rhyolitic eruptions; frothy volcanic glass and thin glass strands
Explain the significance of ignimbrite in volcaniclastic deposits and the conditions under which it forms.
Tuff deposited while hot; welding together to form rock
Examples of Accretionary Prisms
Barbados Ridge; Mediterranean Ridge; Taiwan
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