We had 2 weeks in California; after a weekend in San Francisco and some chillaxin’ by the pool in Sacramento; we took the roadtrip of a lifetime. (many thanks Val x) We visited Lake Tahoe, Mono Lake, Yosemite, Mariposa and drove back to Sacramento via Route 49; the gold rush route…
Trees were more my thing in those days, I armed myself with Stuart and Sawyer’s Trees and Shrubs of California; (ISBN 0520221095) bought for $8 in a second hand bookstore in Berkeley and managed to tick off a fair few… Including this baby:
Statistics: 63.7m high (somewhat truncated by a lightning strike, I guess…) Circumference at ground level: 29.5m, Diameter at 1.5 m from the ground: 7.8m, Estimated bole volume: 963m^3 and old enough to have lived through the action described below!!!
It wasn’t much of a mishap, more of an oversight… We were visiting because my girlfriend (at the time) had seen a picture; something like the one above, and had fallen in love with the desolate beauty of the place. So we went and looked around; we saw the tufa rock formed by accretion of materials at hydro thermal vents and exposed when Los Angeles began tapping Mono Lake’s tributaries; the lake itself is highly saline/ alkaline. We saw Black Point, formed under a much deeper Mono Lake 13,000 years ago; now a flattened cone of basaltic debris. We had a good long look at Negit Island; built by several eruptive episodes between 1600 and 270 years ago. We goggled at Paoha Island created by a magmatic intrusion under the lake between 1720 and 1850; it has an exposed section of rhyolite and 7 (count em’) dacite cinder cones! There was a seismic swarm in 1980 including EQs of up to 6mag (estimated, richter scale) and another in the nearby White Mountain fault in 1986.
Mono Lake is not the whole story; to the south there are a series of domes, coulees, flows and craters stretching all the way to the Inyo Craters; many of these were formed in a series of violent eruptions ~600 years ago. When I say violent I mean phreatomagmatic explosions followed by the opening of a 6km multi- vent fissure, pyroclastic flows affecting the Mono Lake area and then (geologically shortly afterwards) a virtual repeat 40 kms south at the Inyo Craters, followed by coulee and dome building!!! The remaining features are thought to have arisen in the last 2000 years. Mammoth Mountain and the Long Valley Caldera are nearby… Quite a piece of volcanic real estate, I think you’ll agree:
This sums it up pretty well:
The mishap? We were walking around in and admiring an awesome, starkly beautiful landscape, which:
“is considered one of the most likely sites for future volcanic activity in the United States”
according to Gates and Ritchie…
and I had absolutely no idea it was even a volcanic landscape until “yesterday” when I was glancing through their book!!!
Disclaimer: The author is an amateur blogger and has absolutely no quailifications as a geologist or anything of the sort.
The article is not implying that “something is going on” and should give you no cause for concern at this time.
See the USGS website linked below for up to date information.
The United States Geological Survey:
Inspiration for the article from:
Gates and Ritchie’s; Encyclopedia of Earthquakes and Volcanoes, 3rd edition. ISBN0816063028.
Not really a reference; (I nearly put my back out when I picked it up from under the tree!!!) but destined to be a new favourite:
Encyclopedia of Volcanoes; editor in chief Haruldar Sigurdsson. ISBN 012643140x.
GeoLurking Link Recommendations for the nitty gritty. (Note, all links provided documents even though some are in paywall company sites)
“Monitoring Unrest in a Large Silicic Caldera, the Long Valley-Inyo Craters Volcanic Complex in East-Central California” Hill (1984)
“Comparison of risk from pyroclastic density current hazards to critical infrastructure in Mammoth Lakes, California, USA, from a new Inyo craters rhyolite dike eruption versus a dacitic dome eruption on Mammoth Mountain” Kaye et al (2009)
“Elastic source model of the North Mono eruption (1325–1368 A.D.) based on shoreline deformation” Shaffer (2010)
“THE GEOCHEMISTRY OF THE INYO VOLCANIC CHAIN: MULTIPLE MAGMA SYSTEMS IN THE LONG VALLEY REGION, EASTERN CALIFORNIA” Daniel E. Sampson and Kenneth L. Cameron (1987)
Copied from comments for completeness, Schteve.
Alan C Evil Riddel:
Ladies beware! If you have badly fitting undies, you may find me!!
What am I?
What are my origins?
I hope you ladies aren’t offended by this one
Riddle – Name Those Volcanoes
7 Dings 7 points
Variety number 9280, No 1 is used to produce a splendid accompaniment to VC riddle solving!
French FIS WC silver medalist might have crashed on No 2 whilst he learnt to snowboard-cross
No 3 The ‘toy’ volcano (photo below)
16762 No 4 is potentially hazardous and unstable
No 5’s new island emerged, bravely flew the Portuguese flag & vanished just 20 days later
No 6 (photo below)
With a No 7 Bang Bang I wish us all a belated, but very happy & peaceful New Year!