This is a sentiment which, as a geology person, I whole-heartedly endorse. But I was inspired to recaption; no disrespect intended, Mr. Roosevelt.
Oh, the humanity...
Friday, October 2, 2009
LOL Softly, But Carry A Big Font
This is a sentiment which, as a geology person, I whole-heartedly endorse. But I was inspired to recaption; no disrespect intended, Mr. Roosevelt.Oh, the humanity...
IMHO
Stole Ohman's title, too. One of the perks of spending much of my time on the busiest street adjacent to the OSU campus, especially at the beginning of the school year, is the numerous close-call non-accidents I get to witness. Most days, the number is 2-4, and that's just during the times I'm outside smoking or chatting with friends; I'm sure the total is much higher.One of these days, it won't be a close call, or a non-accident; someone will be seriously hurt or killed. I really don't want to see it.
Sometimes the driver's not paying attention, sometimes it's the biker or the skateboarder, or the pedestrian. But texting drivers have been much in the news lately, and given recent studies showing that texting impairs driving ability as much as drunkeness, I'm all for banning it.
Just pay attention, take it slow on Monroe, and be careful, folks. I don't want to have to apply my rusty first-responder training on any of you.
Wednesday, September 30, 2009
The Repupublican Health Plan
Rep. Alan Grayson (D-FL) explains the Republican health care plan.
Via The Daily What
Followup, 5:54 PM: Then he apologizes...
Via Brilliant at Breakfast.
Via The Daily What
Followup, 5:54 PM: Then he apologizes...
Via Brilliant at Breakfast.
Tuesday, September 29, 2009
More On the Gigavolcano
Busy news day... Samoa got double-walloped first by an 8.3 magnitude earthquake, then by a tsunami, with implications for the Oregon coast. (That last link is a very interesting article illustrating how even a very minor tsunami can be dangerous.) Also, the millionaires on the Senate Finance Committee have decided that profitable insurance companies are more important than affordable health care. A gleeful Charles Grassly announced that the next target was the socialist and government-run FBI. "I'm tired of seeing the small-business and entrepreneurial orientation of bank robbers and kidnappers thwarted by government interference with the free market."
Snark aside, the point is, I'm not going to get through a great deal of my news today... I still have 450+ items in my RSS.
But I do want to get back to the teravolcano, and its peta-eruptions, because its 25 km of megaplumbing is ultrafascinating.
I had not heard of this Permian volcanic system before the recent news, and my original intention was to highlight and discuss points in the press release that were interesting and engaging to me. Sadly, I made the mistake of doing a Google for "Ivrea-Verbano Zone and Serie dei Laghi of northwest Italy." Oh my. There's a lot of information to digest.
For example, here we have a very recent field guide to the area (1MB pdf)- a geologic overview rather than a specific trip with stops- dated September 18, 2009.
Another article seems to confirm the hot-spot idea in this diagram of the conjectured structural-thermal evolution of the region.
The point is, there seems to be quite a bit of relatively accessible information on this exposure. In the abstract to the scholarly article in question, Quick et al. claim that "Correlation of ages of volcanic and middle to deep crustal plutonic rocks suggests that they constitute an unprecedented exposure of a subcaldera magmatic plumbing system to a depth of 25 km, and points to a cause and effect link between intrusion of mantle-derived basalt in the deep crust, and large-scale, silicic volcanism." Now this is exactly what has been assumed since my puppy days, back in the early 80's, with respect to Yellowstone. Magma with a basaltic composition rises to the lower crust from the mantle, then some combination of magmatic differentiation (some components solidify earlier, leaving the residual magma with a different composition) and crustal melting (mantle basaltic magmas have temperatures of ~1200 degrees Celsius; crustal rocks melt around 800 C) result in granitic-rhyolitic magma that is relatively enriched in volatiles. In large amounts, this is exactly what's required for explosive volcanism.
So if this is what has been hypothesized, why is this discovery important? Because it's an actual confirmation of the model, not just a theoretically plausible conjecture. I have described the process of doing geology as predicting the past. At first, that seems oxymoronic, but what we do is painstakingly assemble all sorts of data, try to put it together into a coherent picture, then develop a model that explains how that picture came to be. We test the model by saying "If that model is accurate, then we should be able to find A, B and C." Then we go look for A, B and C. In other words, the model involves predictions (A, B, C) that should have already happened at some time in the past, but no one has looked for them. So if we find A, B, and C, it strongly supports our model. And that appears to be exactly what happened in this case.
The next point that is of interest is that the spatial distribution of magma below a volcano is an extremely important, but difficult to investigate, aspect of how and why volcanoes erupt. A recent Accretionary Wedge post by Tuff Cookie talks more about this issue. Certainly there are lots of places around the world where one can observe shallow to deep components of volcanic "plumbing," but the ability to see a section of a single volcanic system, essentially a snapshot in time, through an essentially continuous depth of 25 km (15 miles) is indeed unprecedented, as far as I know. One of the reasons I was so disparaging of the lack of tectonic setting is that each volcano has its own "personality," architecture, eruptive style, compositional range and so on. But not even describing whether the volcano was the result of extension, a hot-spot or subduction would be like describing an organism's behavior without specifying whether the organism was a plant, animal or bacterium. This is one single volcano, which undoubtedly has its own quirks and in many ways is different from any other volcano that has existed. Nevertheless, it can serve as a model for some aspects of many volcanoes, and as a better model for a few.
I knocked the idea of calling this caldera a "supervolcano;" it's nowhere near big enough. I also mocked the very idea of "supervolcano." There are big eruptions, little eruptions and enormous eruptions. Do we really need a special category for the largest few dozen eruptions in the planet's history? Would it make sense to describe the very smallest eruptions as "microvolcanoes?" If your goal is to rivet people to the tube, so they'll sit through the commercials, sure, it's a useful ploy. But in terms of science, it's a minor distinction of degree. Yes, we are particularly fascinating by the extremes, but it doesn't really serve any purpose to set those extremes apart in their own group. Silver Fox made much the same comment in an Accretionary Wedge post a few months ago:
I have been pondering today if I could think of a way in which you could get a "supervolcano" without also getting a caldera. I think the key is that supervolcanoes are explosive. One might erupt an enormous amount of lava in a flood basalt eruption, but that's not explosive (which is the reason the basalt flow illustrating the press release is ludicrous: that kind of lava, and particularly that kind of flow, couldn't be associated with a supervolcano). As the media and pop culture have defined supervolcano though, I think such an eruption would necessarily involve a caldera. But to reiterate a point from yesterday, calderas come in a range of sizes, from a km or so, up to Yellowstone's 45 X 85 km, and perhaps even larger. Only the very largest of those constitute supervolcanoes. One proposed formal definition would define these as erupting a volume of ejecta with a dense rock equivalent of 1000 cubic km or more. Under this definition, even the Long Valley eruption, with a volume of 600 cubic km, falls short- better than halfway there, but not much.
All that said, calderas of any size are formed in dramatically violent eruptions, and any discovery that leads to a better understanding of such events is just fine by me. The "Rosetta Stone" metaphor was a quote from the lead author, and I still feel like it's unjustified hyperbole. Nevertheless, the point he was trying to make was that having an actual physical layout for the system underneath the vent gives us a better way to draw geophysical (heat flow, gravity, seismic, inflation-deflation, and so on) inferences about the activity of magmatic systems where we don't know what the physical layout looks like. So there's some validity to it, but tossing out a term like Rosetta Stone to a staff PR writer is inviting trouble.
I could probably go on, but the point is this: there's lots and lots of fascinating, amazing and important stuff out there in the world. People who write press releases are not on salary to represent that stuff in any accurate, knowledgeable or meaningful way. They get their paychecks for making their employer look good. As I said yesterday, they may from time to time get things right, or write a story about an interesting topic, but it's purely coincidental. I don't hold their ignorance of anything other than how to write a fluffy, catchy story against them. They're doing the job they're being paid to do, and they have the background and knowledge base that the job requires them to have.
But I get pretty furious with "journalists" who have learned to type ctrl "a", ctrl "c", ctrl "v", and think that constitutes doing their job.
Snark aside, the point is, I'm not going to get through a great deal of my news today... I still have 450+ items in my RSS.
But I do want to get back to the teravolcano, and its peta-eruptions, because its 25 km of megaplumbing is ultrafascinating.
I had not heard of this Permian volcanic system before the recent news, and my original intention was to highlight and discuss points in the press release that were interesting and engaging to me. Sadly, I made the mistake of doing a Google for "Ivrea-Verbano Zone and Serie dei Laghi of northwest Italy." Oh my. There's a lot of information to digest.
For example, here we have a very recent field guide to the area (1MB pdf)- a geologic overview rather than a specific trip with stops- dated September 18, 2009.
Together with the metamorphic and igneous rocks of the adjacent Serie dei Laghi (SdL), collectively forming the Massiccio dei Laghi (Boriani et al., 1990), the rocks of the region record Palaeozoic accretion, metamorphic and magmatic processes, the effects of the Hercynian orogeny, post-orogenic magmatic underplating and associated lithospheric stretching and thinning, Mesozoic extension and effects associated with the position of the region in Alpine tectonism (e.g. Handy et al., 1999) (Fig.3).To the extent I have a particular interest in a specific sub-discipline of geology (I don't really), I would probably have to say igneous petrology is it. Petrology is the study of how rocks are formed; igneous petrology deals specifically with rocks that cool and crystallize from a molten state. The above implies, to me at least, that we're dealing with hot-spot volcanism. The ability to look at the compositional variations, along with temperature and pressure as recorded in minerals, from the top of the mantle to the surface of the earth is as exciting as anything I can conceive. And for those of you into structure, there are some diagrams that almost qualify as pornography (see, for example, the bottom of page 8 and top of page 9).
Another article seems to confirm the hot-spot idea in this diagram of the conjectured structural-thermal evolution of the region.
The point is, there seems to be quite a bit of relatively accessible information on this exposure. In the abstract to the scholarly article in question, Quick et al. claim that "Correlation of ages of volcanic and middle to deep crustal plutonic rocks suggests that they constitute an unprecedented exposure of a subcaldera magmatic plumbing system to a depth of 25 km, and points to a cause and effect link between intrusion of mantle-derived basalt in the deep crust, and large-scale, silicic volcanism." Now this is exactly what has been assumed since my puppy days, back in the early 80's, with respect to Yellowstone. Magma with a basaltic composition rises to the lower crust from the mantle, then some combination of magmatic differentiation (some components solidify earlier, leaving the residual magma with a different composition) and crustal melting (mantle basaltic magmas have temperatures of ~1200 degrees Celsius; crustal rocks melt around 800 C) result in granitic-rhyolitic magma that is relatively enriched in volatiles. In large amounts, this is exactly what's required for explosive volcanism.
So if this is what has been hypothesized, why is this discovery important? Because it's an actual confirmation of the model, not just a theoretically plausible conjecture. I have described the process of doing geology as predicting the past. At first, that seems oxymoronic, but what we do is painstakingly assemble all sorts of data, try to put it together into a coherent picture, then develop a model that explains how that picture came to be. We test the model by saying "If that model is accurate, then we should be able to find A, B and C." Then we go look for A, B and C. In other words, the model involves predictions (A, B, C) that should have already happened at some time in the past, but no one has looked for them. So if we find A, B, and C, it strongly supports our model. And that appears to be exactly what happened in this case.
The next point that is of interest is that the spatial distribution of magma below a volcano is an extremely important, but difficult to investigate, aspect of how and why volcanoes erupt. A recent Accretionary Wedge post by Tuff Cookie talks more about this issue. Certainly there are lots of places around the world where one can observe shallow to deep components of volcanic "plumbing," but the ability to see a section of a single volcanic system, essentially a snapshot in time, through an essentially continuous depth of 25 km (15 miles) is indeed unprecedented, as far as I know. One of the reasons I was so disparaging of the lack of tectonic setting is that each volcano has its own "personality," architecture, eruptive style, compositional range and so on. But not even describing whether the volcano was the result of extension, a hot-spot or subduction would be like describing an organism's behavior without specifying whether the organism was a plant, animal or bacterium. This is one single volcano, which undoubtedly has its own quirks and in many ways is different from any other volcano that has existed. Nevertheless, it can serve as a model for some aspects of many volcanoes, and as a better model for a few.
I knocked the idea of calling this caldera a "supervolcano;" it's nowhere near big enough. I also mocked the very idea of "supervolcano." There are big eruptions, little eruptions and enormous eruptions. Do we really need a special category for the largest few dozen eruptions in the planet's history? Would it make sense to describe the very smallest eruptions as "microvolcanoes?" If your goal is to rivet people to the tube, so they'll sit through the commercials, sure, it's a useful ploy. But in terms of science, it's a minor distinction of degree. Yes, we are particularly fascinating by the extremes, but it doesn't really serve any purpose to set those extremes apart in their own group. Silver Fox made much the same comment in an Accretionary Wedge post a few months ago:
Geology and volcanology have seen some warranted increase in notoriety and recognition since the release of movies like Supervolcano, and since the publication of supervolcano articles in popular scientific magazines like Scientific American and Discover, however overdramatized or inexact the popular renditions might be. The Wikipedia article Supervolcano, for example, says that "Supervolcanoes are relatively new to science; they were previously unknown because they do not fit the stereotypical model of volcanoes." This statement is incorrect: very large-scale explosive caldera-forming eruptions have been known to geologists for quite some time. Hey, I knew about them way back in the dark ages, before I reached the age of thirty!I know that the enormous eruptions at Yellowstone had been well-documented by the early 80's when I started in geology, and I think it's important to keep in mind that only 15 years earlier, plate tectonic theory was only starting to be widely accepted in the US.
I have been pondering today if I could think of a way in which you could get a "supervolcano" without also getting a caldera. I think the key is that supervolcanoes are explosive. One might erupt an enormous amount of lava in a flood basalt eruption, but that's not explosive (which is the reason the basalt flow illustrating the press release is ludicrous: that kind of lava, and particularly that kind of flow, couldn't be associated with a supervolcano). As the media and pop culture have defined supervolcano though, I think such an eruption would necessarily involve a caldera. But to reiterate a point from yesterday, calderas come in a range of sizes, from a km or so, up to Yellowstone's 45 X 85 km, and perhaps even larger. Only the very largest of those constitute supervolcanoes. One proposed formal definition would define these as erupting a volume of ejecta with a dense rock equivalent of 1000 cubic km or more. Under this definition, even the Long Valley eruption, with a volume of 600 cubic km, falls short- better than halfway there, but not much.
All that said, calderas of any size are formed in dramatically violent eruptions, and any discovery that leads to a better understanding of such events is just fine by me. The "Rosetta Stone" metaphor was a quote from the lead author, and I still feel like it's unjustified hyperbole. Nevertheless, the point he was trying to make was that having an actual physical layout for the system underneath the vent gives us a better way to draw geophysical (heat flow, gravity, seismic, inflation-deflation, and so on) inferences about the activity of magmatic systems where we don't know what the physical layout looks like. So there's some validity to it, but tossing out a term like Rosetta Stone to a staff PR writer is inviting trouble.
I could probably go on, but the point is this: there's lots and lots of fascinating, amazing and important stuff out there in the world. People who write press releases are not on salary to represent that stuff in any accurate, knowledgeable or meaningful way. They get their paychecks for making their employer look good. As I said yesterday, they may from time to time get things right, or write a story about an interesting topic, but it's purely coincidental. I don't hold their ignorance of anything other than how to write a fluffy, catchy story against them. They're doing the job they're being paid to do, and they have the background and knowledge base that the job requires them to have.
But I get pretty furious with "journalists" who have learned to type ctrl "a", ctrl "c", ctrl "v", and think that constitutes doing their job.
Sarah's New Book
Via BuzzFeed. Rogue used to be a term of condemnation. Rogue animals are often put down because they're dangerous and unpredictable. Not suggestin', just sayin'.But all in all, I have to say, that does seem like an appropriate title.
Followup Fri. Sept. 30: Oh, dear... "Going Rogue" actually is the title of the book. Though at least one news reader hasn't quite figured out how to pronounce it...
| The Daily Show With Jon Stewart | Mon - Thurs 11p / 10c | |||
| Moment of Zen - Going Rouge | ||||
| ||||
Mercury Flyby
The MESSENGER (MErcury Surface, Space Environment, Geochemistry and Ranging; Mercury in the Roman pantheon was also the messenger of the gods) probe will make its final flyby of Mercury in about 2 hours. This is a "gravity-assist" maneuver that will allow the spacecraft to be captured by the planet's gravitational field and go into orbit on its next approach, about a year and a half from now. The Planetary Society blog has a nice set of approach pictures, and the official MESSENGER website has some great photos and a countdown clock. Also, there's a nice rundown of the central questions to be addressed by the mission:
Followup, 4:21 PM: MESSENGER has successfully completed its maneuver, and will start returning data gathered during the fly-by in a couple of hours. Images will be released at about 10 AM Eastern time (7 Pacific) tomorrow, and will be available here.
Followup, Fri. Sept. 30: New Pictures! I'm fascinated by the pit-floor crater.
Question 1: Why is Mercury so dense?Note that most of the questions are equivalent to geology. Even though Mercury is quite close compared to the other planets, it's hard to observe because it's so close to the sun from our perspective. And though intuitively it seems that falling deeper into the gravity well should be easy, there are two issues that make it much more difficult than one might think: first, we're traveling pretty rapidly around the sun. If you want to fall inward, you have to slow your orbital velocity dramatically. Second, on the fall inward, a tremendous amount of gravitational potential energy is converted into kinetic energy; the space craft's velocity, despite its initial decrease, is enormously increased during the fall toward the sun. So if you want to get it to orbit Mercury, you have to slow it down once again when it arrives. Simply put, it's not possible to carry enough fuel (with current technology) to pull this off without some ballistic trickery. MESSENGER has performed 5 "gravity assist" maneuvers already. The last one, today, will allow it to be captured on its next approach.
Mercury's density implies that a metal-rich core occupies at least 60% of the planet's mass, a figure twice as great as for Earth! MESSENGER will acquire compositional and mineralogical information to distinguish among the current theories for why Mercury is so dense.
Question 2: What is the geologic history of Mercury?
Before the MESSENGER mission, only 45% of the surface of Mercury had been photographed by a spacecraft! Using its full suite of instruments, MESSENGER will investigate the geologic history of Mercury in great detail, including the portions of the planet never seen by Mariner 10.
Question 3: What is the nature of Mercury's magnetic field?
Mercury has a global internal magnetic field, as does Earth, but Mars and Venus do not. By characterizing Mercury's magnetic field, MESSENGER will help answer the question of why the inner planets differ in their magnetic histories.
Question 4: What is the structure of Mercury's core?
Through a combination of measurements of Mercury's gravity field and observations by the laser altimeter, MESSENGER will determine the size of Mercury's core and verify that Mercury's outer core is molten.
Question 5: What are the unusual materials at Mercury's poles?
At Mercury's poles, some crater interiors have permanently shadowed areas that contain highly reflective material at radar wavelengths. Could this material be ice, even though Mercury is the closest planet to the Sun? MESSENGER will find out.
Question 6: What volatiles are important at Mercury?
MESSENGER will measure the composition of Mercury's thin exosphere, providing insights into the processes that are responsible for its existence.
Followup, 4:21 PM: MESSENGER has successfully completed its maneuver, and will start returning data gathered during the fly-by in a couple of hours. Images will be released at about 10 AM Eastern time (7 Pacific) tomorrow, and will be available here.
Followup, Fri. Sept. 30: New Pictures! I'm fascinated by the pit-floor crater.
OSU = Rainy Season
OSU classes started yesterday. The students have been trickling in for a couple of weeks, but the hustle and bustle of people scurrying around to and from classes always startles me. After 3 1/2 months of relative peace and quiet, it seems to have vanished all too suddenly.
It's almost stereotypical then, that the other major change was the weather; we've been having highs in the mid 80's through Sunday; yesterday was cloudy with a high in the mid 60's. Then we had a drenching shower in the afternoon. (Note to folks I heard complaining: "showers" does not necessarily mean "light;" it means intermittent, discontinuous, or sporadic. Showers can be quite heavy. Our "rain," on the other hand, tends to persist for days to weeks, and is most often fairly light.)
I enjoy all the seasons here, but I am least fond of and least tolerant of extremely hot weather, so the showers yesterday afternoon through this morning are very pleasant from my perspective. For those allergic to rain, it looks like next week will be a spectacular Indian summer, clear with highs in the mid to upper 70's. And that's fine by me... it means I'll get to smell my favorite odor of all time: petrichor.
And for those for whom ski season can't come soon enough, the spur for this post: it's snowing in the Cascades!
Gawd, I love the seasons in Oregon!
It's almost stereotypical then, that the other major change was the weather; we've been having highs in the mid 80's through Sunday; yesterday was cloudy with a high in the mid 60's. Then we had a drenching shower in the afternoon. (Note to folks I heard complaining: "showers" does not necessarily mean "light;" it means intermittent, discontinuous, or sporadic. Showers can be quite heavy. Our "rain," on the other hand, tends to persist for days to weeks, and is most often fairly light.)
I enjoy all the seasons here, but I am least fond of and least tolerant of extremely hot weather, so the showers yesterday afternoon through this morning are very pleasant from my perspective. For those allergic to rain, it looks like next week will be a spectacular Indian summer, clear with highs in the mid to upper 70's. And that's fine by me... it means I'll get to smell my favorite odor of all time: petrichor.
And for those for whom ski season can't come soon enough, the spur for this post: it's snowing in the Cascades!
Gawd, I love the seasons in Oregon!
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