This Page Hyperlinked [click on] Mount Baker Stratovolcano (background)© ™ ®/ Kulshan Stratovolcano© ™ ®, Simon Fraser University (foreground)© ™ ® ~ Image by Stan G. Webb - In Retirement© ™ ®, An Intelligent Grandfather's Guides© ™ ® next, The Man From Minto© ™ ® - A Prospector Who Knows His Rocks And Stuff© ™ ®
Learn more about the Cascadia Volcanic Arc© ™ ® (Part of Pacific Ring of Fire) Cascadia Volcanoes© ™ ® and the currently active Mount Meager Massif© ™ ®, part of the Cascadia Volcanic Arc© ™ ® [ash flow, debris flows, fumaroles and hot springs], just northwest of Pemberton and Whistler, Canada ~ My personal interest in the Mount Meager Massif© is that the last volcanic vent blew north, into the Bridge River Valley [The Bridge River Valley Community Association (BRVCA), [formerly Bridge River Valley Economic Development Society], near my hometown. I am the Man From Minto© ™ ® - A Prospector Who Knows His Rocks And Stuff© ™ ® Mount Meager Massif© lahar was the largest landslide in Canadian history and one of over 20 landslides to have occurred from the Mount Meager massif in the last 10,000 years. This lahar [a large catastrophic debris avalanche] that flowed to the south, into the Lillooet Valley British Columbia, Canada, on August 6 at 3:27 a.m. PDT (UTC-7). More than 45,000,000 m3 (1.6×109 cu ft) of debris slid down Mount Meager, temporarily blocking Meager Creek and destroying local bridges, roads and equipment. The landslide was large enough to send seismic waves more than 2,000 km (1,200 mi) away into the neighbouring U.S. states of Alaska and Washington and beyond. Multiple factors led to the slide: Mount Meager's weak slopes have left it in a constant state of instability. The massif has been a source of large volcanic debris flows for the last thousands of years, many of which have reached several tens of kilometres downstream in the Lillooet River valley, to the south. It is arguably the most unstable mountain massif in Canada and may also be its most active landslide area. On the north side of the large Mt. Meager massif volcano complex lies Downton Lake Hydro Reservoir, impounded by the La Joi Dam, the uppermost of the Bridge River Project dams. The earliest identified Holocene landslide was in 7900 BP (before the present, or read it as the number of years ago). Further landslides occurred in 6250 BP, 5250 BP, 4400 BP, 2600 BP, 2400 BP, 2240. BP BP, 2170 BP, 1920 BP, 1860 BP, 870 BP, 800 BP, 630 BP, 370 BP, 210 BP, 150 BP and in 1931, 1947, 1972, 1975, 1984, 1986 and 1998. These events were attributed to structurally weak volcanic rocks, glacial unloading, recent explosive volcanism and glacial activity. The last volcano on the top of the massif, however, blew to the north 2,460 years ago, sending talus all the way to Alberta. At the Gold Bridge Golf Course, Bridge River Valley, BC you can play the nine hole course on that talus. . Those who dance with earthquakes and volcanoes are considered mad by those who cannot smell the sulphur. . We begin to deal with BIG (MEGA) EARTHQUAKES at Simon Fraser University (foreground) Kulshan Stratovolcano© / Mount Baker Stratovolcano (background)©New Cascadia Dawn© - Cascadia Rising - M9 to M10+, An Intelligent Grandfather's Guide© next, ~ Images by Stan G. Webb - In Retirement©, An Intelligent Grandfather's Guides©


Countdown to Earthquake Drill - International Great ShakeOut Day is on Thursday, October 20, 2022 at 10:20AM, and annually on the 3rd Thursday in October thereafter - -

Monday, November 12, 2018

Earth's Extremes - Volcanoes in Oregon, United States #Part 2


Planetedge
Published on Aug 13, 2016
Thanks for watching... Jackies Butte Mount Jefferson
https://en.wikipedia.org/wiki/Mount_J...)
Jordan Craters
https://en.wikipedia.org/wiki/Jordan_...
Maiden Peak
https://en.wikipedia.org/wiki/Maiden_...)
McDermitt Complex Mahogany Mountain
https://en.wikipedia.org/wiki/Mahogan...
Mount McLoughlin
https://en.wikipedia.org/wiki/Mount_M...
Middle Sister
https://en.wikipedia.org/wiki/Three_S...)
Newberry Caldera
https://en.wikipedia.org/wiki/Newberr...
North Sister
https://en.wikipedia.org/wiki/Three_S...)
Olallie Butte
https://en.wikipedia.org/wiki/Olallie...
Pelican Butte
https://en.wikipedia.org/wiki/Pelican...
Rocky Butte
https://en.wikipedia.org/wiki/Rocky_B...
Round Butte Saddle Butte South Sister
https://en.wikipedia.org/wiki/Three_S...)
South-Central Oregon Volcanics Strawberry Volcanics Mount Tabor
https://en.wikipedia.org/wiki/Mount_T...
Mount Thielsen
https://en.wikipedia.org/wiki/Mount_T...
Three Fingered Jack
https://en.wikipedia.org/wiki/Three_F...
Tower Mountain caldera Mount Washington
https://en.wikipedia.org/wiki/Mount_W...)
Western Cascades
https://en.wikipedia.org/wiki/Western...
Wildcat Mountain caldera Source:
https://en.wikipedia.org/wiki/List_of...
Music: Smooth Ridin,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.  The continental plate rises above, and 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.

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