Earth's Extremes - Volcanoes in Oregon, United States #Part 1

https://youtu.be/m3k_jn3mTMI  [1:46 minutes]

Planetedge

Published on Aug 7, 2016

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Mount Bachelor
https://en.wikipedia.org/wiki/Mount_B...
Bald Mountain Caldera https://volcanoes.usgs.gov/volcanoes/...
Mount Bailey https://en.wikipedia.org/wiki/Mount_B...)
Belknap Crater https://en.wikipedia.org/wiki/Belknap...
Black Butte https://en.wikipedia.org/wiki/Black_B...)
Blue Lake Crater https://en.wikipedia.org/wiki/Blue_La...
Broken Top https://en.wikipedia.org/wiki/Broken_Top
Brown Mountain https://en.wikipedia.org/wiki/Brown_M...)
Cinnamon Butte https://en.wikipedia.org/wiki/Cinnamo...
Columbia River Basalt Group https://en.wikipedia.org/wiki/Columbi...
Crater Lake or Mount Mazama https://en.wikipedia.org/wiki/Mount_M...
Crooked River caldera https://en.wikipedia.org/wiki/Crooked...
Diamond Craters https://en.wikipedia.org/wiki/Diamond...
Diamond Peak https://en.wikipedia.org/wiki/Diamond...)
Fort Rock https://en.wikipedia.org/wiki/Fort_Rock
Gorda Ridge https://en.wikipedia.org/wiki/Gorda_R...
Gray Butte Mount Hood https://en.wikipedia.org/wiki/Mount_Hood
Source: https://en.wikipedia.org/wiki/List_of...
Music: Raindrops,Huma-Huma; YouTube Audio Library A volcano is a
rupture on the crust of a planetary mass object, such as the Earth,
which allows hot lava, volcanic ash, and gases to escape from a magma
chamber below the surface. Earth's volcanoes occur because the
planet's crust is broken into 17 major, rigid tectonic plates that
float on a hotter, softer layer in the Earth's mantle. Therefore, on
Earth, volcanoes are generally found where tectonic plates are
diverging or converging. For example, a mid-oceanic ridge, such as
the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic
plates pulling apart; the Pacific Ring of Fire has volcanoes caused
by convergent tectonic plates coming together. Volcanoes can also
form where there is stretching and thinning of the crust's interior
plates, e.g., in the East African Rift and the Wells Gray-Clearwater
volcanic field and Rio Grande Rift in North America. This type of
volcanism falls under the umbrella of "plate hypothesis"
volcanism. Volcanism away from plate boundaries has also been
explained as mantle plumes. These so-called "hotspots", for
example Hawaii, are postulated to arise from upwelling diapirs with
magma from the core–mantle boundary, 3,000 km deep in the Earth.
Volcanoes are usually not created where two tectonic plates slide
past one another. Erupting volcanoes can pose many hazards, not only
in the immediate vicinity of the eruption. One such hazard is that
volcanic ash can be a threat to aircraft, in particular those with
jet engines where ash particles can be melted by the high operating
temperature; the melted particles then adhere to the turbine blades
and alter their shape, disrupting the operation of the turbine. Large
eruptions can affect temperature as ash and droplets of sulfuric acid
obscure the sun and cool the Earth's lower atmosphere (or
troposphere); however, they also absorb heat radiated up from the
Earth, thereby warming the upper atmosphere (or stratosphere).
Historically, so-called volcanic winters have caused catastrophic
famines. At the mid-oceanic ridges, two tectonic plates diverge from
one another as new oceanic crust is formed by the cooling and
solidifying of hot molten rock. Because the crust is very thin at
these ridges due to the pull of the tectonic plates, the release of
pressure leads to adiabatic expansion and the partial melting of the
mantle, causing volcanism and creating new oceanic crust. Most
divergent plate boundaries are at the bottom of the oceans;
therefore, most volcanic activity is submarine, forming new seafloor.
Black smokers (also known as deep sea vents) are an example of this
kind of volcanic activity. Where the mid-oceanic ridge is above
sea-level, volcanic islands are formed, for example, Iceland.
Subduction zones are places where two plates, usually an oceanic
plate and a continental plate, collide. In this case, the oceanic
plate subducts, or submerges under the continental plate forming a
deep ocean trench just offshore. In a process called flux melting,
water released from the subducting plate lowers the melting
temperature of the overlying mantle wedge, creating magma. This magma
tends to be very viscous due to its high silica content, so often
does not reach the surface and cools at depth. When it does reach the
surface, a volcano is formed. Typical examples of this kind of
volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire.