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25 November 2015
Altered states (of lava domes)
Time for some shameless self-promotion – but also some research blogging. Last week I (finally) had a paper come out about my graduate modeling work on the hydrothermal systems and alteration in lava domes. (I’m sorry it’s not open access – I couldn’t afford it this time! But feel free to contact me if you want a copy.) Basically, the rundown is this: Lava domes, like volcanoes in general, are big …
23 July 2015
Domes galore: Obsidian Dome, Long Valley
For the final dome in our volcanology day back in my May Long Valley field trip, the W&M students and I took a short hike up to Obsidian Dome. The Obsidian, Glass Creek and Deadman Creek domes all erupted around 1350 CE, which makes them some of the youngest features in the Long Valley area. The three domes are aligned north-south and probably all erupted from the same dike, which …
28 June 2015
Domes galore: Mono Craters, Long Valley
Being the guest lecturer on a geology trip is great, especially if you get to talk about your favorite geologic features. But what does one do when volcanology day is over and it’s time for the students to do a moraine mapping project? Naturally, sit on a convenient rock and observe some lovely lava domes.
9 June 2015
Domes galore: Panum Dome, Long Valley
Oh, man. Summer is a terrible time for keeping up with blog posts, but I’ve had a good reason to be absent – I was off in Denver on business and slightly wilder parts of California with my alma mater’s summer field course. I mean, what geologist could pass up the chance to tag along on a trip to Long Valley and Yosemite? During the Long Valley and Mono Lake portion of the trip, I actually did do a little work, serving as the trip’s volcanology expert and talking about lava domes as much as anyone would let me. Because Long Valley may be a beautiful caldera and the site of one of the world’s largest eruptions, but it also has domes. Boy, does it ever have domes.
22 April 2013
Remembering to be small: Accretionary Wedge #56
As geologists, we spend a lot of time looking for the big picture. We want to know how a mountain range formed, or where tectonic plates were millions of years ago, or what global repercussions an eruption could have, or what effect the melting of an ice sheet could have on sea level around the world. We think about time in boggling spans that far exceed anything we could experience in a single lifetime – millions, even billions of years. And we are always trying to tell far-reaching stories to explain the history of our planet, using words and figures and photos.
28 November 2012
Increased activity at Santiaguito
A quick note for today: It appears that activity at the Santiaguito lava dome complex in Guatemala has increased significantly, with collapses occurring at the lava flow on the southeastern flank of the Caliente dome. Plumes are visible on GOES satellite images and are reaching 5 km in height (plumes from ash-and-gas eruptions of Caliente are usually less than 1 km high).
27 October 2011
More “translating”: The 1929 dome collapse at Santiaguito
Last week I talked about “translating” eyewitness accounts of the 1902 eruption of Santa Maria in Guatemala. As all of you probably know by now, the Santiaguito lava dome complex started growing in the 1902 eruption crater in 1922. At first there was just one dome (which was called Santiaguito then and which we now call Caliente). There isn’t much in the literature about the early days of the dome growth; most of the accounts we have about the area come from German explorers Karl Sapper (an ethnographer and linguist) and Franz Termer (a professor of geography and anthropology).
4 July 2011
Report on IVM-Fund trip to Guatemala: Part 3
From April 29 – May 3, 2011, Dr. Jeff Witter of the International Volcano Monitoring Fund (IVM-Fund) made a trip to the Santiaguito Volcano Observatory (OVSAN) to deliver a set of volcano monitoring equipment. This equipment was purchased with the proceeds from a fundraising effort that I and the OVSAN personnel conceived of and that Jeff helped put into action. Jeff did a great writeup of his experiences in Guatemala, and asked that I share it with everyone who has contributed to the fundraiser.
18 June 2011
Favorite geology word: Autobrecciation (Accretionary Wedge #35)
Well, ash-flow tuff got taken pretty quickly, but I’m fairly certain no one will come up with my favorite geology term (or the particular meaning I’m going to talk about). That word is autobrecciation. I’m not talking about the autobrecciation that happens when the surface of a lava flow breaks up and gets incorporated into a lava flow, but the meaning used in several volcanology papers about rockfalls and lava dome collapses: volatile-rich, pressurized lava dome rocks fragmenting explosively in response to rapid decompression, which occurs at a critical pressure difference between the overpressurized rock and the surrounding environment (i.e., the point when the pressure overcomes the tensile strength of the rock). As you can see in the video, the rocks basically disintegrate into a lot of fine material (and probably some leftover rock chunks), which is the perfect recipe for a pyroclastic flow.
10 June 2011
Valles Caldera
I meant to post this last year after my brief trip to Los Alamos, but now that I’m back on the Hill for the summer, it seems a shame not to show off the scenery!
The Jemez Volcanic Field in northern New Mexico – which includes the Valles Caldera – straddles the Rio Grande Rift in the east and the Colorado Plateau in the west. The Jemez contains volcanic rocks erupted from >13 to 0.13 million years ago, with compositions ranging from basalt (low silica content) to rhyolite (high silica). The best known of these is the Bandelier Tuff, a thick sequence of pyroclastic deposits which were erupted in several phases around 1.62 to 1.25 million years ago. The total volume of material in the Bandelier is around 300 cubic km (~75 cubic miles), and it covers much of the area in the Jemez Volcanic Field. (The Bandelier tends to be unwelded and relatively soft, and canyons have cut down through it in many places, creating wonderful vertical exposures as well as the mesas and plateaus that Los Alamos is built on.)
Jessica Ball is a volcanologist at the U.S. Geological Survey, researching volcanic hydrothermal systems and stability, and doing science communication for the California Volcano Observatory. She previously worked at the Geological Society of America's Washington DC Policy Office, learning about the intersection of Earth science and legislative affairs. Her Mendenhall postdoc and PhD focused on how water affects the stability of volcanoes, and involved both field investigations and numerical modeling applications. Her blogging covers a range of topics, from her experiences in academic geosciences to science outreach and communication to her field and lab work in volcanology.