Week 3 Flashcards
Volcanos are
openings or vents, with
or without a conical hill or mountain
near them
Volcanoes occur in
the Pacific Ocean
in what is called the “Ring of Fire”
What causes rock to melt? (3)
1) High temperature
2) The melting temperature depends on the depth in the earth and the amount of available water
3) Hot rock deep in the earth may melt by increasing its temperature, decreasing its pressure or adding water to shift the melting curve to lower temp
Stratovolcanoes/Composite
Felsic lava & cloud of hot white gases; 1000 to 4000 meters high and 10 to 30 km wide; Large, steep-sided cone (i.e., Mount St. Helens or Mount Baker)
Caldera - Deep depressions volcano
A caldera is a large cauldron-like depression that forms following the evacuation of a magma chamber/reservoir. When large volumes of magma are erupted over a short time, structural support for the crust above the magma chamber is lost; Eruptions produce rhyolite to open calderas 50 or more kilometers across
Shield Volcanoes Malfic lava
an extremely large basalt lava volcano, such as those in Hawaii (Mauna Loa), with gently sloping sides
hotspot volcano
an isolated volcano, typically not on a lithospheric plate boundary, but lying above a plume or hot column of rock in Earth’s mantle
hot spring
a place at which hot water reaches the ground surface
types of volcanic eruptions (4)
hawaiian, strombolian, vulcanian, plinian
Hawaiian eruptions
such as those of the basalt shield volcanos Kiluaea and Mauna Loa in Hawaii are also generally not explosive, although some produce small quantities of pyroclastic debris
Strombolian eruptions
are named for a volcano off the west coast of Italy that has erupted many times a day for the last 2000 years; it is fed by fluid basalt magma that interacts with seawater. Rapidly expanding steam bubbles in the magma blow it into cinders, lapilli bombs and blocks that fall around the vent and tumble down steep slopes to form a pyroclastic cone; magma = extremely fluid, so the eruptions are generally mild
Mount Erebus (Antarctica’s only known active volcano)
Strombolian
Vulcanian eruptions
are named for the island of the north coast of Sicily that gave its name to the landform and is named for the Roman god of fire; fed by highly viscous, andesitic magmas that are rich in gas; dark eruptions clouds blow out blocks of volcanic rock along with ash, lapilli and bombs; tephra eruptions dominate but PDC flows and lava flows emanating from the base can develop with or follow the eruptions; common and have relatively low VEI values, they are not without danger
Plinian eruptions
are named in honour of the edler, a roman scientist who went to Pompeii to investigate Mount Vesuvius in AD 79 and died in the eruption; 1998 eruption at Mount Etna; widely in force and magnitude, ranging from smaller eruptions such as at Etna and Rabaul to that of Tambora volcano in 1815, the largest volcanic eruption with a written historical record
Pelean eruption
named for mount Pelee in Martinique in the Caribbean are relatively rare; the rhyolite, dacite or andesite eruptions can be violent; most distinctive however is the growth of a huge steep sided dome; at intervals the sides of the expanding dome collapse to form searing hot flows of pyroclastic speeds exceeding 500 km per hour; these incandescent pyroclastic density currents (PDCs) are the distinguishing feature of this style of eruption
