My understanding is that there are some relatively recently active volcanic areas in the southwestern US, in New Mexico, Arizona, and California–including an eruption only 1,000 years ago in Arizona. What is the source of this volcanism? A hot spot?
(I guess it’ll be a short thread if my guess happens to be correct.)
I know absolutely nothing about this, but I’m curious. Do you have any links that have a less detailed description than what you’re looking for?
In Northern California:
Mt. Shasta erupted in 1786 and erupts about once every 800 years.
Mt. Lassen erupted in about 1915.
Not aware of ones in the Southwest.
You can Goolge these with the name of the mountain and the word “erupt”.
Bingo.
Sunset Crater, the Youngest Cone on the Colorado Plateau, 1064-1065 AD.
[tinfoil hat]
The hotspot has moved, and will soon manifest as a supervolcano in central Utah.
Why else the recent earthquake cluster there ?
[/tinfoil hat]
Thanks, Squink. But now I wonder what it means by “some geologists.” Is this not a generally accepted explanation? Based on the widsom acquired in all of two college geology courses, I can’t come up with any other explanation, but of course if I were sure of myself, I wouldn’t have asked.
That is pretty vague, but it’s derived from this USGS fact sheet, so it might be the best information available, unless an actual geologist shows up with details.
Hot springs and other such manifestations of volcanic activity occur all the way up the eastern side of the north-south mountain chains in California. Most of them are relatively small. I personally know of several on the northern edge of San Bernardino at the foot of Waterman Canyon. Further north, the Coso Range in Inyo County has numerous geysers and hot springs and active geothermal power plants. Further north, around Mammoth (eastern Sierra Nevada) there are a number of such springs. A friend and I were fishing at June Lake late in the year and the night before we came home it snowed and the weather was cold and damp. As we came down the grade into the caldera in the Mammoth Springs region we could see steam vents all over the place. There must have been half dozen or mayber a couple more than that. These surface evidences of volcanism continue all the way up the western US. Some of it is near the coast and is a result of the relative motions of the North Amercan and Pacific geologic plates. In other cases it is merely the result of volcanic activity near the surface in what is a geologically active area. Where do you think all of those mountains come from? The whole western US is being continually crumpled, compressed, stretched, lifted, dropped and in general moved around. All the motion is on a long time scale, but the North American plate and the Pacific plate are moving relative to each other something like an inch/year along the San Andreas fault.
Here’s just a blurb on the “Valley of the Fires” in New Mexico. This wasn’t that particularly long ago, and was a resulted in a rather significant flow.
http://www.newmexico.org/place/loc/destinations/page/DB-place/place/571.html
The Smithsonian’s Global Volcanism Program has a wicked cool site listing all known volcanos active during the Holocene.
3 in New Mexico: http://www.volcano.si.edu/world/region.cfm?rnum=1210
2 in Arizona:
http://www.volcano.si.edu/world/region.cfm?rnum=1209
19 in California:
http://www.volcano.si.edu/world/region.cfm?rnum=1203
It looks like there are lots of hot springs in New Mexico, which I’m guessing have to do w/something volcanic. I don’t really know anything about this though.
I probably should have added that these volcanic activities are ongoing and have been so for thousands of years. They are far from “recent.”