Supervolcanos!

[Turtle]

i haven't found a name or other identifier for the particular indian ocean basin at the location of the antipodes to long valley supervolcano and columbia basalts hotspot pictured above. remembering that i looked because the latest research/researchers explicitly suggested to look, what i see on the google earth imagery looks to me like a crater field. :eek: :doh: not only do the red antipode dots seem to be in the center of 300 mile circular structures, zooming out a bit reveals a couple more that appear, to me, to have mascons. i have to wonder if no one has done something so simple as to look on google earth, or perhaps looked but didn't have my bias, or looked with a bias & still didn't see anything, or looked, saw, but can't/won't say on account of it's not strong enough evidence??? well, don't want to get too caught up in that knot just yet until i flesh out my speculations. :D

 

i'm still looking for geologic studies of the specific basin holding the antipodes, but i found a good source with some leads and summations of geologic studies in the area to date.

 

Indian Ocean :: Physiography and geology -- Britannica Online Encyclopedia

Physiography and geology » Origin

The origin and evolution of the Indian Ocean is the most complicated of the three major oceans. Its formation is a consequence of the breakup, about 150 million years ago, of the southern supercontinent Gondwana (or Gondwanaland); by the movement to the northeast of the Indian subcontinent (beginning about 125 million years ago), which began colliding with Eurasia about 50 million years ago; and by the western movement of Africa and separation of Australia from Antarctica some 53 million years ago. By 36 million years ago, the Indian Ocean had taken on its present configuration. Although it first opened some 125 million years ago, almost all the Indian Ocean basin is less than 80 million years old. ...

 

so from this we can, erhm...must, conclude that any impact structure on the floor of the indian ocean is less than 80 million years old. haven't checked on the age of long valley, but the columbia basalts erupted between 6 & 17 million years ago. CVO Website - Columbia River Flood Basalts - Map the game is afoot. ;)

[Turtle]

been off hunting to see if i could find anything on anomolous horizons in the ~18 million-year-old range and it's no go so fo. :D ;) i was thinking an impact big enough to leave a 300 mile crater is gonna leave some irridium spread over the globe similar to the KT boundry. still, got off on some interesting tangents, which brings us to this study. these guys say a very large impact can cause a supervolcano right where it hits, and cause a melt that completely destroys the crater. now dat's da bomb!! so it goes.

 

http://www.mantleplumes.org/WebDocuments/JonesSpringer2003.pdf

[quote name=Adrian P Jones1, David G Price1, Paul S DeCarli1*, Neville Price1 and Richard

Clegg2]Abstract. We examine the potential for decompression melting beneath a

large terrestrial impact crater, as a mechanism for generating sufficent quantity of

melt to auto-obliterate the crater. Decompression melting of the sub-crater mantle

may initiate almost instantaneously, but the effects of such a massive melting

event may trigger long-lived mantle up-welling or an impact plume (I-plume) that

could potentially resemble a mantle hotspot. ...

[Turtle]

been off hunting to see if i could find anything on anomolous horizons in the ~18 million year old range and it's no go so far. :( :hyper: i was thinking an impact big enough to leave a 300 mile crater is gonna leave some irridium spread over the globe similar to the KT boundry. still, got off on some interesting tangents, which brings us to this study. these guys say a very large impact can cause a supervolcano right where it hits, and cause a melt that completely destroys the crater. :eek2: now dat's da bomb!! :ebomb: so it goes.

 

http://www.mantleplumes.org/WebDocuments/JonesSpringer2003.pdf

[quote name=Adrian P Jones1, David G Price1, Paul S DeCarli1*, Neville Price1 and Richard

Clegg2]Abstract. We examine the potential for decompression melting beneath a

large terrestrial impact crater, as a mechanism for generating sufficent quantity of

melt to auto-obliterate the crater. Decompression melting of the sub-crater mantle

may initiate almost instantaneously, but the effects of such a massive melting

event may trigger long-lived mantle up-welling or an impact plume (I-plume) that

could potentially resemble a mantle hotspot. ...

[Buffy]

Latest update on the Yellowstone Supervolcano:

 

Every day, the supervolcano lurking under Yellowstone National Park belches up 45,000 metric tons of carbon dioxide — much more than could be produced by the known magma chamber that lies just below the surface. Now, scientists have spotted a source of the excess gas, and it’s a doozy. They’ve discovered a magma pool containing enough hot rock to fill the Grand Canyon 11 times...While large, the researchers say, the reservoir is only 2 percent melted rock and is too deep to contribute to a supervolcanic eruption akin to the explosion that formed the Yellowstone caldera around 640,000 years ago. The estimated odds of an impending Yellowstone doomsday remain exceedingly slim, the authors assure. Even so, the discovery should help volcanologists better assess the hazards posed by the supervolcano.

 

Source: Massive Magma Pool found deep below Yellowstone, Science News, 4/23/2015

 

Although "slim odds" may still include "in your lifetime"...

 

Cool animation at the link too. 

 

 

A volcano may be considered as a cannon of immense size, :phones:

Buffy

[Moontanman]

Latest update on the Yellowstone Supervolcano:

 

 

Although "slim odds" may still include "in your lifetime"...

 

Cool animation at the link too. 

 

 

A volcano may be considered as a cannon of immense size, :phones:

Buffy

 

I am on the east coast and i am sure it would still ruin my life and all my fellow beach bums.. 

[pgrmdave]

As far as I can tell it won't affect DC too much.  My friend who lives in Colorado, on the other hand, will be buried under ash.

[HydrogenBond]

The largest of the volcanoes in the Tharsis Montesregion, as well as all known volcanoes in the solar system, is Olympus Mons. Olympus Mons is a shield volcano 624 km (374 mi) in diameter (approximately the same size as the state of Arizona), 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp. A caldera 80 km (50 mi) wide is located at the summit of Olympus Mons. To compare, the largest volcano on Earth is Mauna Loa. Mauna Loa is a shield volcano 10 km (6.3 mi) high and 120 km (75 mi) across. The volume of Olympus Mons is about 100 times larger than that of Mauna Loa. In fact, the entire chain of Hawaiian islands (from Kauai to Hawaii) would fit inside Olympus Mons!

 

 

​The reason this volcano is so large compared to on earth is the crustal plates on the earth slide more sort of sealing up old volcanos and causing new ones to appear. This result is the magma flow from the mantle is more distributed. On Mars, less sliding of plates allows this volcano to persist, and grow over time. 

 

Yellowstone would be under the impact of crustal sliding, which can seal it, redistribute it, or even reopen it. 

Edited May 2, 2015 by HydrogenBond

[CraigD]

The reason this volcano is so large compared to on earth is the crustal plates on the earth slide more sort of sealing up old volcanos and causing new ones to appear.

I think that’s one of the factor for Mars’ volcanos being so much taller than Earth’s, but not the only one. Others include differences between Mars’ and Earth’s gravity and atmosphere. Mars’ lower gravity (0.376 g) means tall surface features spread, collapse, and subside less than on Earth. Mars’ thinner (0.006 ATM) and drier atmosphere means Martian features erode less than on Earth.

 

When I studied them in school in the 1970s and ‘80s, few people though Mars had tectonic plates at all. Recently (ca 2012?), that thinking has changed. Analysis of high resolution photographs of Valles Marineris, which ca 1980 most people thought was due either to ancient water erosion or ancient surface cracking, show that its “matching sides” have slid about 150 km, so now many scientists believe Mars has 2 roughly equal-sized plates, like a spherical jar split in its middle. (see “Does Mars have tectonic plates?”, Jan 2014 SpaceAnswers.com)

 

Nobody’s sure it Mars’ tectonic plates are still moving, or are temporarily or permanently stopped. Surprisingly given all the vehicles that have been landed on Mars since the first ones in the 1970s, and that even early ones like Viking 1 carried seismometers, we don’t have high-quality seismometer data from Mars, which could detect such movement. Viking 1 may have detected a marsquake in 1976, or may have just been rocked by wind. Hopefully this situation will be much improved in 2016, when InSight, the first Mars lander designed specifically for seismometry, is scheduled to land.

 

There’s uncertainty, too, about how Mars’ volcanos formed, and whether a given one is active, dormant, or extinct.

 

The lava fields around Olympus Mons’ appear to be older (time since last lava flow), around 150,000,000 years, while about 1200 km southeast, the fields of the 3 Tharsis Montes, in decreasing age from south to north Arsia, Pavonis, Ascraeus, appear younger, some of Ascreaus’ possibly 2,000,000 years or younger.

Even if new thinking about Mars’s tectonic plates is correct, the plates haven’t moved enough to account for the difference in apparent age of the lava fields around its volcanos, leading to speculation that, rather than as on Earth, where hot spot/mantle plumes are stationary and the crustal plates move over them, on Mars the crustal plates are stationary and the plumes move under them. (see "Martian Volcanoes May Not be Extinct", Oct 2007 Space.com)

 

This strikes me as having profound implications for terrestrial geology, because it supports the plume hypothesis, which holds that mantle plumes exist for long periods and are responsible for volcanic hot spots, over the alternative plate hypothesis, which holds that the mantle is mostly homogenous, and hot spots occur due entirely to plate tectonics.