Long Valley
eklemetti | February 3, 2010With all the talk of the current Yellowstone earthquake swarm, I thought it would worth it to write a post on the the structure and caldera - and why we get earthquake swarms that are structurally rather than magmatically-related.
First off, lets think about why calderas formed. This is relatively simple - at least superficially. The land (or volcano) above a magmatic system is partially supported by that magma, especially because magma is hot and buoyant. The isostatic support by the magma holds up the land surface or volcanic edifice, so when an eruption expels a large volume of magma, this…
eklemetti | September 30, 2009The big geology news right now is the M8 earthquake in American Samoa that generated a killer tsunami (which made it all the way to the Bay Area in California).
Mammoth Mountain in California's Long Valley region.
In more benign, volcano-related news:
The aviation alert level at Redoubt in the Alaska has been returned to Green/Normal, which means that for all intents-and-purposes, the eruption that started earlier this year is over. The new dome totals ~91 million cubic yards of lava, slowly adding back to the north side of the volcano.
Eruptions reader Doug C. pointed out to me that there…
eklemetti | May 27, 2009You'll have to excuse the curtness of this post. An bad hop in softball will do that to you.
Here's some news:
Mt. Dempo in Indonesia
Xinhua offers some nice pictures of the current activity going on at the summit crater at Nyiragongo in the Congo. Note the partially-crusted-over lava lake in the first shot. The Red Cross is updating the evacuation and mitigation plans for the area as the volcano shows increased activity.
The alert level at Mt. Dempo in Indonesia was raised to the second highest level. There has been ash fall (as far as 10 km from the vent) and volcanic gas emissions. The…
eklemetti | April 15, 2009Busy day so I probably won't get to update much as we're busy hosting Dr. Charlie Bacon, geologist for the USGS, here at UC Davis today. Dr. Bacon has written some seminal papers in his career and is probably the foremost authority of the evolution of Crater Lake/Mt. Mazama (speaking of which, >a new geologic map for the Park was recently released) and the caldera-forming eruption. He's also a really nice guy.
If you want to read some of his papers, you might try these:
Bacon, C.R., Implications of silicic vent patterns for the presence of large crustal magma chambers, in: D.P. Hill, R.A…
eklemetti | November 11, 2008
I just got back from a 4 day field trip to the Long Valley Caldera in eastern California, so I'm a little behind on posting. The field trip was great and I had a chance to see a lot of pumice, a lot of welded tuff (in the form of the Bishop Tuff, the large ignimbrite that erupted from the Long Valley Caldera ~760,000 years ago) and got to lead the part that looked at the Mono domes (too bad snow covered the Inyo Domes). Pictured above some puffed obsidian - the layers are obsidian and vesicle-rich obsidian - that were erupted, cooled, expanded and cracked (known as "breadcrusting"). This is…