The Looming Volcanic Giant of Northern California: Mt. Shasta

So California is all about earthquakes, right? Oklahoma has tornadoes, Florida has hurricanes, Minnesota has blizzards,and California has the San Andreas fault (and all the other active faults that no one seems to remember the names of). But really, California has a "little" of everything, and we have a "big" of volcanoes. I was on my way home today from family Thanksgiving celebrations in Oregon, and while we traveled down Interstate 5, we had some simply awesome views of California's gigantic volcano, Mount Shasta.

Shasta is the second tallest volcano in the Cascades Range at 14,179 feet (4,322 m) after Mt. Rainier, but in bulk it is the largest composite cone/stratovolcano in the range (Medicine Lake Highland, also in California, has more volume, but is a shield volcano that doesn't even reach 8,000 feet in elevation). The mountain is composed largely of andesitic lava flows and ash deposits, but also includes outpourings of basalt and dacite. It has been active for more than half a million years, and may have last erupted in 1786. It has had eruptions on average every 600 years or so, making it the second most active volcano in the Cascades after Mt. St. Helens.

Shasta is a composite cone in the truest sense. At least five distinct volcanoes in various stages of disrepair make up the mountain. The earliest collapsed around 350,000 years in a gigantic debris avalanche that flowed 28 miles north to the vicinity of Yreka (the nature of the slide was not recognized until the 1980s after St. Helens produced a similar avalanche with a length of 12 miles). The Sargents Ridge and the Misery Hill cones erupted, became dormant and were deeply eroded by glacial activity. Shastina erupted around 9,800 years ago forming a large satellite cone that is actually the third highest volcano in the Cascades. Hotlum Cone is the currently active volcanic center, having erupted fairly often during the last 9,000 years.

Shasta has seven active glaciers, including the longest and most voluminous in California. Meltwater from the glaciers will occasionally cause destructive lahars or volcanic mudflows. Other dangers lurk on the flanks of the volcano, where some 20,000 people live. Ash flows, lava flows and even a caldera collapse are possible hazards to those who live in the shadow of the mountain.

The mountain is famous for mythology and legends as well. The native Americans certainly understood the power of the mountain, having witnessed some of her eruptions. The prominence of the giant edifice has resulted in all manner of speculation about the gods and aliens who call the mountain home. Many consider the mountain to be a "global power center" or "spiritual energy vortex". The existence of the mountain alone makes it magical for me, but folks seem to take this stuff seriously. I was in a crystal shop this afternoon listening to a strange and earnest conversation about chemtrails and spiritual vibrations. Books abound about the Lemurians and other societies that live inside the volcano. They've got it all figured out...

Shasta is a beautiful mountain, and a looming volcano that is capable of creating havoc. On this particular day, all was peaceful and serene. We enjoyed the sight during our long journey.

Eruptions Across the American West? Uh, no...

Why, oh why, is this a conspiracy? Someone on YouTube says they think that weather radar thunderstorm images are volcanic eruptions, and the news spreads so fast that a U.S. Geological Survey official has to issue a statement saying that there is no eruption going on. A government denial, of course, is a gold mine for conspiracy nuts, because it gives them some kind of stature. It becomes a story that may or may not fade away...especially as 2012 and the end of the world approaches!

The most ironic thing about this supposed eruption is that the Pisgah Crater sits in full view of Interstate 40 east of Barstow (most of the other alleged eruptions are near highways, too). An eruption would have been reported and photographed by literally thousands of travelers.

Eric Klemetti of the geoblog Eruptions, as always, has the full story. Check it out.

Is it possible that a volcanic eruption could take place in California or anywhere else in the American West? Absolutely! The possibilities range from phreatic (groundwater) explosions at places like Death Valley or Mammoth (look up Inyo Craters or Ubehebe Craters), cinder cone eruptions at dozens of localities (Modoc Plateau, Cascades, Basin and Range, Coast Ranges), somewhat more violent eruptions of plug domes or stratovolcanoes (Mt. Shasta or Lassen Peak), and even the highly unlikely rhyolite caldera eruption of a place like Mammoth Lakes (Long Valley Caldera). California had an eruption sequence at Lassen from 1914 to 1917. The thing is, if an eruption were imminent, the government and U.S. Geological Survey would be actively monitoring events and working to protect lives and property. You can't hide a volcanic eruption, and really, why would anyone try?

I'm sort of disappointed that my UFO and alien post last week didn't go viral this way! The picture above is the Black Rock Crater, a 20,000 year old basalt flow in the Lunar Crater Volcanic Field in central Nevada. It is one of hundreds of young cinder cones scattered across the American West.