Volcano Flashcards
is the process in which magma, which is buoyant than the surrounding rock, rises to the surface and becomes lava.
Volcanism
Any vent or built-up mountain where lava, pyroclastic materials, and/or gases erupt
Volcano
where lavas erupt, divergent boundaries manifests as
ridges or fissures
Melts are produced by
decompression melting
the partial melting of the hot asthenosphere due to decreased lithostatic pressure, exerted by the thinned overlying lithosphere
decompression melting
Volcanism at divergent boundaries manifest as
mid-ocean ridges (MOR)
Divergent boundaries that occur within continental plates are known as, where diverse manifestations of volcanism can occur. This is due to the partial melting of both the crust and the mantle which creates complex variety of features
continental rifts
occurs once substances like volatiles and water are added to rocks, resulting in melting into magma.
Flux melting
occurs due to the ascent of mantle plumes to the base of the lithosphere
Intraplate volcanism
manifests as a chain of extinct volcanoes similar to a conveyor line, with only the youngest volcano being active
Hot Spot volcanism
magma accumulates underground in an open space or an area of highly fractured substrat
magma chamber
central vent (shaped like a vertical pipe), a flank vent (smaller conduits issuing from a central vent),
conduits
are rock sheets that can form from magma when they seep into cracks in rocks
dikes
beds of rocks that form as a result of rock formation between layers of older materials
sills
end of a pipe-like conduit at the top of the mound
crater
Eruptions issuing from flank vents can produce
parasitic cones
These domes form when viscous lava cannot flow too far due to the viscosity and cools into a mound.(roughly circular)
Lava dome
broad gently-sloping mounds shaped like a soldier’s shield
Shield Volcano
They form when low-viscosity basaltic lava is allowed to flow freely from a vent; over time, these flows stack upon each other, forming the volcano.
Shield Volcano
are tall, steep, conical mountains
Composite volcanoes or stratovolcanoes
They form by the accumulation of various successive erupted materials; differing layers of pyroclastic flows and lava flows
Composite volcanoes or stratovolcanoes
are small, steep mounds composed of tephra or volcanic fragments formed by explosive eruptions.
Pyroclastic cones
4 most active volcano
Mt. Kanlaon, Mt. Bulusan, Taal Volcano, Mayon Volcano
Potentially active
Mount Apo, Cuernos de Negros, Mount Isaro
Inactive
Mount Arayat, seven lakes of Laguna
Eruptions are considered _______ when they produce lava flows exclusively.
Effusive
_______ eruptions produce pyroclastic debris due to the sudden release of built-up pressure. It is usually associated with high gas content and high viscosity magmas.
Explosive
are driven by thermal expansion of the dissolved gases in lava
Magmatic eruptions
result from the extreme buildup of gases in the magma chamber and conduit
Plinian eruptions
are very similar to Vulcanian eruptions, except that they are of greater magnitude
Peléan eruptions
result from more viscous lava, which slows down bubble formation and clogs up conduits
Vulcanian eruptions
are sustained fissure eruptions, producing curtains of basaltic lava
Icelandic eruptions
are the result of the bursting of clumps of gas bubbles at the surface, throwing up clots of lava
Strombolian eruptions
produce low-viscosity basaltic lava flows and fountains
Hawaiian eruptions
occurs in a shallow body of water, and are usually characterized by strong explosions as a result of magma coming in contact with water
Surtseyan eruption
These eruptions are driven by the violent thermal contraction of magma when it interacts with water, resulting in an explosion
Phreatomagmatic Eruptions
These are purely steam-driven, caused by the expansion of water into steam when heated by a nearby magma chamber or volcanic source.
Phreatic Eruptions
If earthquake magnitudes are measured using the Richter scale, the volcanic counterpart of this scale is
Volcanic Explosivity Index (VEI)
he primary products of eruptions are
lavas
When cools, lava may form
fine-grained volcanic rock, volcanic glass
composition of lavas, along with temperature, determine their physical properties, most notably their _____
viscosity
is best measured against the silica content of the lava, with more siliceous or silica-rich melts being more viscous.
Viscosity
Lava is extruded as a lava flow, or a moving stream of lava and flows are classified based on _____ content
silica
are silica-depleted and very hot, and thus have a very low viscosity when erupted.
Basaltic flow
is a low-viscosity flow with wrinkled, billowing, or ropey surfaces.
Pahoehoe
More viscous flows produce ___ or broken, rubbly, spiny surfaces.
a’a
Interiors of basaltic flows cool more slowly and may contract into well-formed hexagonal columns perpendicular to the flow. This is known as
columnar jointing
are said to have intermediate viscosity, and cannot flow as easily as basaltic lava
Andesitic flows
do not typically move further than 10 km.
Andesitic flows
are the most silica-enriched and have the lowest temperatures
Rhyolitic flows
volcanoes eject large quantities of fragmental igneous debris, which accumulate into
volcanoclastic deposits
are any volcanic fragments produced directly by eruptions
Pyroclastic debris
are thin glass filaments formed when thin lava strands were frozen
Pelé’s hair
Glass droplets are also called
Pelé’s tears
Erupting lava fountains eject blobs of spatter, which can accumulate into spatter cones and spatter ramparts around a vent or fissure.
random
Magma and lava contain dissolved fluids, which are released as _____ during eruptions.
gases
can comprise as much as 9% of magma, and contribute to a melt’s viscosity.
Volatiles
High-viscosity magmas trap bubbles (known as _______), leading to pressure buildup and eventual explosions.
vesicles
is the internal heat of the Earth
Geothermal Energy
is a confined area where groundwater transfers heat from a source to a heat sink and is the basis for energy exploitation
geothermal system
takes the form of a shallow magmatic intrusion or naturally high geothermal gradients
heat source
is the vessel of heat and is what power plants extract to power turbines
geothermal fluid
is a volume of permeable rock which stores geothermal fluid and can be exploited at a profit
reservoir
Power Plants extract geothermal fluids by drilling into __ the reservoir
production wells
The loss of pressure at the surface and the fluid’s temperature turns the fluid into _ ; this _ is used to drive turbines and generate electricity.
steam
Used geothermal fluid is cooled and condensed back into the water, which is either dumped at the surface or injected back underground using re-injection wells.
random
In the Philippines, the first geothermal plant was a 2.5 kW pilot plant at barrio Cale in __ put up in 1967.
Tiwi, Albay
The first commercial plant in operation was the 3MW pilot plant in __.
Tongonan, Leyte
At present, the Philippines is the _ largest producer of geothermal power in the world behind the USA, providing 12.2% of the country’s electricity.
second
At present, there are eight producing geothermal fields around the country, with 31 service contract areas in pre-development.
Producing fields include Makban in Laguna and Quezon; Tiwi, Albay; Bacman in Sorsogon; Tongonan, Leyte; Palinpinon, Negros Oriental; the Northern Negros Geothermal Project on Mt. Kanlaon; Maibarara, Batangas; and Mount Apo in North Cotabato and Davao.
random
Advantages
Geothermal energy is an attractive business venture due to its low cost.
Geothermal energy is also renewable, relying on the practically limitless heat of the Earth.
Disadvantages
Geothermal fluids are pollutants, containing dissolved metals and ions and having higher temperatures.
Improper handling may contaminate water tables or surface waters.
These fluids contain greenhouse gases such as carbon dioxide and hydrogen sulphide, among others.
Power plants require large areas of cleared land for pipelines and drilling rigs. Careless extraction can empty a reservoir.
Over-extraction and hydraulic fracturing can generate earthquakes in the vicinity.
