Wednesday, February 24, 2010

Essential reading for volcanologists

One of the things I've found out since starting serious research in volcanology is that a lot - and I mean a lot - of the best texts are either out of print, expensive, or both. Fortunately there are enough people in the department that we have a fairly good selection of them - better than the library, anyway - although we're going to be in big trouble when certain folks graduate. (Either that or we're going to have to kidnap their collections.)

Anyway, being a bookish type, and having noticed the other book reviews that have come out on the geoblogosphere lately, I thought I would begin working my way through a list of the books that I've found most useful over the last year or so. Granted, I haven't used all of these extensively, but this will give me a good chance to refresh my memory on what I could be using. A lot of these texts combine general and specific subject matters, so it's a little hard to divide them up by specialty, but I'll try and go from really general to more specific.
In most cases I've linked to Amazon, mostly because they do pretty decent summaries of content, but these books are often available straight from the publisher, or from independent booksellers (for a greatly reduced price). is where I start whenever I'm looking for an obscure book, although beware of inflated prices for out-of-print editions. 

Saturday, February 20, 2010

Volcanic clays

Another big part of my PhD research concerns volcanic clays. Volcanoes are a really interesting example of multiple natural cycles operating at once - not only do they create new rock, they also break it down. This could be pretty quickly - blasting lava into ash in an eruption - or slowly, through hydrothermal processes. When you get a combination of hot rocks and water, you (eventually) get alteration minerals, and some of those include clays.
This is a major concern in terms of volcano stability. Clays are weaker than the rocks that they form from, and an informal term that volcanologists use for hydrothermally altered rock is "rotten rock". In some cases, the reduction in stability is a function of the clays themselves, which are layered minerals and thus likely to shear along particular planes; in other cases, the reduced stability is because of what clays do, which is block or absorb water. Clays are made up of layers of tetrahedral and octahedral structures, and depending on how those layers are arranged (and how many times the tetrahedra repeat in a layer), a clay can either act as a barrier to water, or absorb it and expand (these are known as "shrink-swell clays"). If a clay blocks water, it could create a slippery plane within a volcanic edifice, which would make it easier for the rock above it to fail and collapse. Kaolinite clays are an example of this. If a clay absorbs water and shrinks or swells, this constant movement could also destabilize the material above it (smectites and like montmorillonite are good examples here.)

But the dangers don't stop there. Clays, in a collapse of a volcanic edifice, can increase the runout of the debris or mudflow that may result; this occurred in Nicaragua in 1998 at the Castia volcano, when a hurricane caused part of an old lava dome complex to collapse, and the smectite clays that had formed in the domes from hydrothermal processes helped form a massive lahar that traveled more than 10 km. It's also a concern at a number of Cascade volcanoes, including Mount Rainier; even if the volcanoes haven't erupted in a long time, there are still active hydrothermal systems within their flanks, altering the volcanic rocks there to weaker materials. Multiple studies have attempted to map these alteration zones and determine where a collapse might occur based on the location and extent of particular clay minerals.

Further Reading:

Crowley, J.K., Hubbard, B.E. and Mars, J.C., 2003. Analysis of potential debris flow source areas on Mount Shasta, California, by using airborne and satellite remote sensing data. Remote Sensing of Environment, 87(2-3): 345-358.

John, D.A., Sisson, T.W., Breit, G.N., Rye, R.O. and Vallance, J.W., 2008. Characteristics, extent and origin of hydrothermal alteration at Mount Rainier Volcano, Cascades Arc, USA: Implications for debris-flow hazards and mineral deposits. Journal of Volcanology and Geothermal Research, 175(3): 289-314.

Opfergelt, S., Delmelle, P., Boivin, P. and Delvaux, B., 2006. The 1998 debris avalanche at Casita volcano, Nicaragua: Investigation of the role of hydrothermal smectite in promoting slope instability. Geophysical Research Letters, 33(15): 4.

Reid, M.E., Sisson, T.W. and Brien, D.L., 2001. Volcano collapse promoted by hydrothermal alteration and edifice shape, Mount Rainier, Washington. Geology, 29(9): 779-782.

Sheridan, M.F. et al., 1999. Report on the October 30 1998 rockfall/debris avalanche and breakout flow of Casita volcano, Nicaragua, triggered by Hurricane Mitch. Landslide News, 12: 2-4.

Wohletz, K. and Heiken, G., 1992. Volcanology and Geothermal Energy. Los Alamos Series in Basic and Applied Sciences. University of California Press, Berkeley.

Zimbelman, D.R., Rye, R.O. and Breit, G.N., 2005. Origin of secondary sulfate minerals on active andesitic stratovolcanoes. Elsevier Science Bv, pp. 37-60.

Tuesday, February 16, 2010

Dome collapses

In light of the recent dome collapse at Soufriere Hills, I thought I'd expound a little on the subject, which is a major part of my research. Lava domes, if they last long enough, tend to go through cycles of growth and collapse. These can be relatively short, like the domes at Soufriere Hills or Mt. St. Helens (remember, a few years is short even on a volcanic timescale), or long, like at Casita volcano in Nicaragua or my own study area of Santiaguito. The collapses vary in volume: a smallish collapse might comprise a few million cubic meters of material (the 1929 collapse at Santiaguito was about 3 million cubic meters), but the collapse of an entire dome might be in the 100s of millions of cubic meters. 

There are a number of reasons why domes collapse. One is gravity; domes can grow on steep slopes or overspill summit craters, which means that parts of them can become very unstable and simply collapse because of their own weight. Another trigger might be an earthquake, which can shake loose dome rock; yet another trigger might be an eruption, which could loosen or even blow up significant portions of a dome. (This could be what happened at Soufriere Hills; there have been some pretty spectacular Vulcanian eruptions going on at the same time as dome-building there.)

My research, however, focuses on how water can cause dome collapses over short and long timescales.  In the short term, intense precipitation events (large storms or hurricanes) have been known to cause domes to collapse (especially at Soufriere Hills). This likely has something to do with water saturating the domes to the point where it can penetrate deep into hot dome rock, and either a) sealing in magmatic gases or b) sealing itself in and vaporizing in cracks and fractures. Either way means that pressure builds up in the dome and water can lubricate structural breaks, which reduce the stability of the dome. In the long term, a dome with an active and well-supplied hydrothermal system can form lots of clays, which are very weak and can also trap water. (Some clays even swell when they absorb water, which pushes dome rock around and destabilizes it that way.) This seems to be what happened when some old domes at Casita Volcano in Nicaragua collapsed and formed a devastating lahar, or mudflow of volcanic material.

What I intend to focus on at Santiaguito is why the domes there haven't experienced any major collapses in the 80 years they've been growing, and what part of the complex might be most likely to fail if a collapse did occur. This is going to involve looking at water-dome interaction in both the short and long term; I'm mixing in hydrology and clay mineralogy with my volcanology, and on this trip I hope to collect clay samples from the inactive domes in the complex. (I am not going anywhere near Caliente, the erupting dome, if I can help it; those videos of people standing on the rim during eruptions are just insane. I've met people who were at Galeras when it erupted in 1993, and I've heard enough about what can happen that I have no intention of putting myself in that kind of danger.)

Further Reading:

Barclay, J., Johnstone, J.E. and Matthews, A.J., 2006. Meteorological monitoring of an active volcano: Implications for eruption prediction. Journal of Volcanology and Geothermal Research, 150(4): 339-358.

Calder, E.S., Luckett, R., Sparks, R.S.J. and Voight, B., 2002. Mechanisms of lava dome instability and generation of rockfalls and pyroclastic flows at Soufriere Hills Volcano, Montserrat. Geological Society, London, Memoirs, 21(1): 173-190.

Elsworth, D., Voight, B., Thompson, G. and Young, S.R., 2004. Thermal-hydrologic mechanism for rainfall-triggered collapse of lava domes. Geology, 32(11): 969-972.

Fink, J.H. and Anderson, S.W., 2000. Lava domes and coulees. In: H. Sigurdsson, B.F. Houghton, S.R. McNutt, H. Rymer and J. Stix (Editors), Encyclopedia of Volcanoes. Academic Press, San Diego, California, pp. 307-319.

Harris, A.J.L., Rose, W.I. and Flynn, L.P., 2003. Temporal trends in lava dome extrusion at Santiaguito 1922-2000. Bulletin of Volcanology, 65(2-3): 77-89.

Matthews, A.J. et al., 2002. Rainfall-induced volcanic activity on Montserrat. Geophysical Research Letters, 29(13): 1644-1647.

Sapper, K. and Termer, F., 1930. Der Ausbruch des Vulkans Santa María in Guatemala vom 2-4 November 1929. Zeitschrift für Vulkanologie, 13: 73-100.

Sheridan, M.F. et al., 1999. Report on the October 30 1998 rockfall/debris avalanche and breakout flow of Casita volcano, Nicaragua, triggered by Hurricane Mitch. Landslide News, 12: 2-4.

Taron, J., Elsworth, D., Thompson, G. and Voight, B., 2007. Mechanisms for rainfall-concurrent lava dome collapses at Soufriere Hills Volcano, 2000-2002. Journal of Volcanology and Geothermal Research, 160(1-2): 195-209.

Voight, B. and Elsworth, D., 2000. Instability and collapse of hazardous gas-pressurized lava domes. Geophysical Research Letters, 27(1): 1-4.

Saturday, February 13, 2010

Roughing it - Guatemala la segunda parte

Yes, I've been hinting at some fieldwork that I'm going to do for the next two weeks - and it's back in Guatemala!

If  you remember the posts I put up last year about my first visit, you'll also remember that quite a bit less science happened than I was hoping, thanks to some nasty little microscopic critter that found its way into my food. I really, really don't want to repeat that experience this year, so I'm going down armed with a supply of antibiotics and Gatorade powder. This year's trip is going to be a little more ambitious; we're planning a five-day hike to the lava domes at Santiaguito, and I'm going to be collecting as much clay as I can. (Why not rocks? Volcanic clay is my topic of interest at this volcano - more on that in subsequent posts.)

At any rate, I'll be out of touch for a bit, although I do promise to update when I can. In the meantime, I've scheduled a few posts about some of my subject matter, and volcanology in general. And there will be great photographs to show off when I get back!

Wednesday, February 10, 2010

A local waterfall in winter

Of course, local for me means Niagara Falls. I took a trip up on Saturday to get myself outdoors for a little while, and while I'm pretty sure no important parts of me were permanently frozen, it was effing cold up there. (Not very snowy, though. It's pretty ironic that I moved away from the Washington DC area, and they're now poised to get more snow than Buffalo this year. I think Buffalo's at about 60 inches, and if DC gets another foot or so with today's storm, they'll have us beat. Not that Buffalo is the snowiest place in New York by any means - that's Syracuse. But I digress.)

One interesting thing I found out about Niagara Falls in the winter is not only is it cold, it's damp. This is a direct result of all the spray from the Canadian and American Falls. It looks like the US gets the worst the spray off Horseshoe Falls, since the prevailing winds blow from west to east. Anyway, it makes for a somewhat hazardous visit, because everything is covered with ice.

The ice gets really thick in places, and you can see how the layers were built up. This chunk came off a light pole. It's stratification on a vertical plane!

Quite a bit of the park on the NY side was closed off, presumably because it was so slippery and they didn't want people too close to the water. 

A little artsy shot with a chunk of ice rime:

As it turns out, I have a habit of standing in almost exactly the same spots when I take photos up here. It's likely that this is just because those are the clear (and well-framed) shots, but it means I can show some neat comparisons between the winter and summer versions of Niagara Falls. As always, click to embiggen:

In the winter, because tourism is slow, the hydroelectric companies on both sides of the Niagara River restrict the water going over the Falls to about half of its full capacity (which means that around 50,000 cubic feet/second or 1,400 cubic meters/second). In the summer, somewhere around 10-25% of the flow is diverted, depending on the level of Lake Erie, which feeds the Falls.

The Canadian side really has the better views, but on the American side you get to wander around on Goat Island, which sits in between the Horseshoe (Canadian) and American Falls. Here's a couple of shots from the top of Goat Island:

Here's a brave little seagull and his favorite spot - I'm hoping the rock will be there when the ice melts!:

Looking upstream at both sets of falls:

And again:

It's pretty neat to see how things change by season. The icepack in the river gets pretty thick, so those Maid Of The Mist boats that you see going out the rest of the year are all beached, and no one goes down to the observation decks (and who'd want to get drenched in the middle of winter? Not me!)

I'll try to get a few more posts out this week, since I'm going to be in the land of sporadic internet access for the rest of the month. More on that later!

Friday, February 5, 2010

Blast from the past

On Wednesday the volcanology lab groups here at UB had a discussion about basaltic eruptions, particularly at Paricutin and Jorullo volcanoes in Mexico. The first thing I was reminded of on hearing the name Paricutin was not a geological fact, but a childhood memory - one of watching Reading Rainbow, actually.

Reading Rainbow, if you aren't familiar with it, was one of the best children's shows out there. Sadly, it ended in 2006, but in its 23 year run, host Levar Burton and any number of celebrity narrators did wonders to keep kids reading and show them that books were not only worth their time, but fun and exciting to boot. Each episode was divided between book reviews and readings - sometimes by well-known celebrities like Julia Child and James Earl Jones, to name a couple - and Levar Burton visiting people and places related to the theme of the episode. It was one show that my parents were happy to let me watch any time it was on, and they'd usually try and find the books for me to read afterward. It's sad that it's no longer going, but hopefully reruns will still pop up on public television stations.

In fact, a few of those early episodes - reruns for me, since I wasn't around to watch their first runs - were responsible for starting me on a geologic path. I particularly remember one episode called Hill of Fire, in which the featured book talked about a volcano that suddenly appeared in a Mexican cornfield - Paricutin, of course. I thought this was totally fascinating, and probably asked my parents if we could have a volcano in our backyard, or something like that. And now that I'm in graduate school, I can look back on what I remember of that show and use it as a basic context for understanding the professional papers I'm reading. How cool is that?
Another episode talked about one of my favorite childrens' book series: The Magic Schoolbus. Who doesn't love Ms. Frizzle and her crazy bus? Of course, the book was The Magic School Bus Inside the Earth, which I'm sure I made my mother go out and buy for me right afterward. These books were a great introduction to science topics, because they gave you the facts as a part of a narrative. Sneaky! Plus it's always fun to see what clothing Ms. Frizzle is going to wear next. Personally, I want some of those jumpsuits for when I do fieldwork.

Not to mention Three Days On a River In a Red Canoe. It's not about geology, but it was my first intro to camping. I didn't do any serious camping until I was in college, but this episode definitely had me out in the backyard for a few nights that summer. I have yet to take a canoe trip, however...perhaps a goal for this summer?

Obviously, these aren't the only geology/outdoors-related children's books out there, but they are a few of my favorites - and I remember them after fifteen years or so because of Reading Rainbow.