Yellowstone eruption
 

http://en.wikipedia.org/wiki/Yellowstone_National_Park

http://en.wikipedia.org/wiki/Yellowstone_Caldera

http://en.wikipedia.org/wiki/Supervolcano

http://en.wikipedia.org/wiki/Long_Valley_Caldera

http://en.wikipedia.org/wiki/Valles_Caldera

I saw this a while back on Discovery. Apparently Yellowstone is past due for a massive eruption. What effects would this have on the geography after TEOTWAWKI?

VEI 8+, right?

Have a look at
http://pubs.usgs.gov/fs/2005/3024/

(from one of the links at the wiki entry for supervolcano):

Scroll down to
'PREHISTORIC CALDERA-FORMING ERUPTIONS OF YELLOWSTONE'
and look at the map.

Huckleberry Creek/Lava Ridge ash beds are VEI 8 size. They range from California to Louisiana and stretch up into Minnesota and southern Canada.

Now those ash beds are several feet (metres) deep at their *edges*.
Closer in to the volcano, the ash gets thicker, and there's more rock and molten material. Then you get to the caldera, which in Yellowstone's case is about 34 miles (55 km) by 45 miles (72 km).

How much of that will be molten rock is unclear. Certainly it's going to be difficult to get close to the caldera without special equipment (heat, toxic gases).

The rest of the continental US and much of southern Canada is going to be blanketed with ash falls, depending on prevailing winds.

The global effects are limited by the amount of stratospheric dust injection and the sulphate load (cooling aerosol)...

I was thinking more along the lines of what effect it would have on the game. When it happens, you'll have a nuclear winter effect for a couple years, which means famines. When it occurs in the timeline will determine how much effect it has in game. If it occurred 140 years ago, it'll reshape some geography, but most of it's effect will be gone, except for making part of the US unrecognizable to the PCs. OTOH, if it happened 6 months before waking up, it may impede the PCs immediately and provide some natural challenges.

Darkwing wrote:
I misinterpreted this:
Given the area buried in ash, a significant fraction of the Project's assets may be damaged or destroyed.

As you point out, timing is everything.
Note the relatively rapid recovery of plant life using Mount St. Helens as an example:
http://www.fs.fed.us/gpnf/mshnvm/dig...reandafter.htm

This article looks like a good overview of recovery rates:
http://faculty.washington.edu/moral/...DM_Grishin.pdf

Data from Hawaii:
http://www.nps.gov/history/history/o...5/contents.htm

Of course one of the woefully inaccurate Soviet warheads may have detonated in the weakest point of the caldera, and Ka-boom!

WallShadow wrote:
Only in some bad Bay/Emmerich pastiche.

The magma chamber is too deep for even a 20-25Mt surface burst to do that. Its uppermost point is about 3.5 miles (~6km) beneath the surface.

Ground shock at that depth would be negligible, despite the 500m crater depth and the ~2.5km (1.5 mile) fireball radius.

http://news.nationalgeographic.com/n...me-larger.html

Soviet missiles were pretty accurate by the 1970s.
SS-18 Mod 1 or 3 with the 20-25Mt warhead had a CEP of 1000m according to the Soviets; western estimates were 300-550m.

Have a look at the Global Security website for details.

http://www.globalsecurity.org/wmd/wo...sia/index.html

The diameter of the fireball is 2.5km, not the radius.
My mistake.

Our current (classic-era) campaign features a Yellowstone eruption in 2020. There are several meters of ash deposited on Wyoming, Colorado, etc. ... my referee map has notations on ash depth here and there.

Except for boltholes and facilities within ~100 km of Yellowstone, there wasn't any direct effect on Project bases. However, there might be a few meters of ash on top of your bunker!

Roads and other remains of 20th Century civilization are pretty hard to find in the ash-covered areas.

http://tywkiwdbi.blogspot.com/2009/0...fall-maps.html

A few weeks later, possibly in sympathy, we had the Long Valley Eruption.

http://volcano.oregonstate.edu/vwdoc...ng_valley.html

http://vulcan.wr.usgs.gov/Volcanoes/...framework.html

--
Michael B.