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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.
17 April 2011
Soufriere Hills Volcano: The Belham River Valley
It’s snowing again, so in order to avoid being depressed by the weather, I thought I’d post a few photos of the Belham River Valley on Montserrat. The Belham, which drains into the sea on the west side of Montserrat, channels both pyroclastic flows and lahars from the Soufriere Hills lava dome. Prior to the eruption, the valley held a number of houses and the island’s only golf course, but material from the eruption has since filled the valley bottom and made it unwise to live too close. Volcanic and volcaniclastic processes are constantly reshaping the landscape there, and having visited two years in a row (here’s the link to last year’s post about the Belham), I thought I’d see if any of my photos were good for before and after comparisons.
20 September 2010
Distinguishing deposits from andesitic eruptions
Telling apart different kinds of deposits associated with volcanic eruptions isn’t always easy. There are a lot of factors that can affect their appearance: the location and type of eruption, the magma/lava type, where they’re emplaced, etc. On Montserrat, volcanologists are lucky to have both ancient and modern deposits; they can look at what’s currently being erupted and compare it to the older volcanics on the island. We did quite …
7 May 2010
Volcano Vocab #4: Lahar
As suggested by a commenter on the last Volcano Vocab post, here’s a water-and-volcano-related term for you: Lahar (“lah-haar”). Lahar is an Indonesian word for a mudflow of volcanic material – that is, a mass movement of volcanic debris that contains some amount of water. (A dry flow of volcanic material would usually just be called a debris flow or debris avalanche.) The key thing that distinguishes a lahar from a …
15 March 2010
Looking backward: Past eruptions at Volcán Santa Maria
On our way to visit the Santiaguito Volcano Observatory, Gustavo Chigna of INSIVUMEH (the Guatemalan equivalent of the USGS) was kind enough to take an afternoon off and show us some of the older deposits near Santiaguito. Our first stops were at an exposure of the air-fall deposit from the October 24, 1902 eruption of Volcán Santa Maria. This eruption was a devastating one, stripping the land for more than …