Sunday, August 19, 2018

New Location

In preparation for the release of a book (tentatively titled "Ask a Geologist") this blog is now being updated monthly at the following location:

http://www.askageologist.com/


Friday, June 8, 2018

Will Yellowstone Blow?



If you’re being shot at, there is some satisfaction in knowing how often you’re being shot at. You can at least plan, and perhaps take some mitigating steps. To this end, the entire Pacific Northwest is preparing for the next magnitude 8+ subduction earthquake event by seismically retrofitting public buildings and holding “Great Shakeout” drills. This planning and preparation can be applied to volcanoes, even super volcanoes.

Q: Do geologists know when Yellowstone might erupt again? It appears to erupt at a Supervolcano level every few hundred thousand years.

The first was: 2,100,000 years ago
Second was: 1,200,000 years ago
And the last one was: 640,000 years ago

Are we in any danger of a fourth one?
- Brandon F


A: Yes is the short answer. Probably not in your lifetime is the long answer. There have been supervolcano eruptions moving with time along the Snake River Plain to modern Yellowstone starting at least 16.5 million years ago in southeastern Oregon.
Volcanologists in the USGS Volcano Science Center are very aware of this eruptive periodicity – we have a full-time volcanologist assigned to Yellowstone as the Scientist-in-Charge (SIC) of the Yellowstone Volcano Observatory. He works in close coordination with seismologists at the University of Utah, and with the US Park Service. Some links might be of interest to you:

https://volcanoes.usgs.gov/volcanoes/yellowstone/

https://volcanoes.usgs.gov/volcanoes/yellowstone/yellowstone_publications.html
There have been other, somewhat smaller eruptions at Yellowstone, however: The Scaup Lake rhyolite flow of 250,000 years ago, and a more recent hydrothermal blow-out about 70,000 years ago. Neither would have been trivial if you had been in the area, but they did not have the continental reach of the huge monsters you list.
You might want to check out the USGS Yellowstone hazard assessment:
Christiansen, R. L., Lowenstern, J. B., Smith, R. B., Heasler, H., Morgan, L. A., Nathenson, M., Mastin, L. G., Muffler, L. P. & Robinson, J. E. (2007). Preliminary Assessment of Volcanic and Hydrothermal Hazards in Yellowstone National Park and Vicinity. U.S. Geological Survey Open-File Report , 2007-1071, 98 p.
To make this a bit more real, there is a silvery-white ash deposit found all over most of the United States, sometimes called the Lava Creek Tuff (from a site locality in Kansas) or the Pearlette Ash Formation in older scientific literature. I have visited a single layer of this material near Colorado Springs, CO. There it is over 20 meters/70 feet thick; when it came down it may have been over 30 meters thick, but was consolidated with rainfall and the compressive weight of overlying material since then. This blanket of ash smothered all living things beneath it; I have personally pulled out a paleo-camel’s tooth from the bottom of the deposit. It ALL came from Yellowstone, over 800 kilometers/500 miles away!
Here’s what a future eruption might do (From Mastin, Van Eaton, and Lowenstern, 2014, “Modeling ash fall distribution from a Yellowstone supereruption”, Geochemistry, Geophysics, Geosystems, Vol 15, Issue 8, https://doi.org/10.1002/2014GC005469): 
 
Figure 1. Likely distribution of ash and tephra from a future Yellowstone Caldera eruption (Mastin, Van Eaton, and Lowenstern, 2014). Fine details will depend on wind distribution and the volume of the erupted ash.

Note that this is for a sophisticated 3D grid model that assumes prevailing westerly winds up to 16 – 24 km elevations. However, the model shows that the erupting plume would make its own prevailing winds, something that would allow an “umbrella cloud” to leave ash deposits throughout ALL conterminous US states, something consistent with geologic mapping of previous eruptions. 

Another point is relevant here. Our experience is that, while you cannot predict an earthquake, you CAN predict a volcanic eruption if you have adequate instrumentation on the volcano. Several of our USGS staff returned recently from making their annual gravity and geodetic GPS survey (these surveys will detect any magmatic inflation). The caldera and surrounding terrane are very well-instrumented with telemetered seismometers, also.
The assessment of the Scientist-in-Charge when I last talked with him is that we are not likely to have a super-eruption in our lifetimes – that's essentially what the 2007 assessment above says. I will excerpt key pieces of that assessment here:

“No volcanic eruption has occurred in Yellowstone National Park or vicinity in the last 70,000 years or more.”

“One statistical measure of eruption probabilities based on this episodic behavior suggests an average recurrence of 20,000years. The fact that no such eruption has occurred for more than 70,000 years may mean that insufficient eruptible magma remains beneath the Yellowstone caldera to produce another large-volume lava flow."
Table 5. Estimates of annualized probability of events greater than a given magnitude.
Diameter (m)       Area (m2)    Events in last 14 thousand years     Annualized Probability
                >2                           3.1               7000 (estimated)                                   0.50
            >300                  70,700                      16                                                      0.0013
          >2000             3,140,000                        2                                                      0.00014”

This last table is from page 83 of the report. The chances for a large hydrothermal eruption next year (NOT a super volcano eruption) is just a bit over 1 in 10,000. For reasons explained above, the probabilities are likely even lower than this.
Bottom line: Those in the know are not currently worried about a Yellowstone “blow.”
A more recent paper (Lowenstern, Sisson, and Hurwitz, 2018, “Probing magma reservoirs to improve volcano forecasts”, EOS Vol. 99, No. 6, pp. 16-21) helps explain the uncertainties involved. Seismic tomography studies suggest that the Yellowstone magma reservoir is about 5%-15% melt, with all the rest being crystals that have slowly formed over the last several hundred thousand years. That’s still about 25 cubic kilometers of melt, larger than any volcano has spewed out on Earth since the eruption of Tambora (Indonesia) in 1815 caused the Year Without Summer in Europe, with snow in June and mass starvation following crop failures.
The current understanding in the volcanology community is that a magma reservoir is not eruptible with less than 50% melt… however, this assumes a homogeneous distribution of crystals and melt fraction. Looking closely at the steep compositional gradients in crystals erupted 250,000 years ago at Yellowstone, calculations suggest that the crystalline mush had lain dormant for ~220,000 years – but then was remobilized in as little as a mere 10 months.
The main concern is that if there is another injection of hot basalt from the mantle into the base of this reservoir, it could remobilize the reservoir and become eruptible in less than a year.
In the meantime, the volcano is very closely monitored 24/7. Please understand that there are a number of scientists within and outside of the US Geological Survey who are monitoring Yellowstone, literally, on an hourly basis. They think about your question every day. 
~~~~~

Wednesday, May 2, 2018

Risks of Working in a Rock Shop

 Q: Greetings,
     I work for a small business rock shop that carries a very large variety of gemstones and minerals. I have wondered for quite some time if I should be concerned about exposure so certain elements like lead, arsenic etc. We handle mostly everything without gloves or the use of dust masks.
     I am now pregnant and even more concerned about this. I know that doctors and other professionals will advise the use of safety precautions regardless. My question is not that if we should use precautions, because I know that we should anyways. The question I am asking you, is if there is plausible serious risk through skin contact and inhalation? Do you know of any risks, are you able to provide specific examples of situations where problems have occurred /or might occur?
     One example is of the handling of iron pyrite. It leaves behind black residue (we do use gloves for this) and creates a strong smell and dust in the air. Am I exposing myself to something serious here?
     Also, I’ve heard of a new fad where the folks who believe in metaphysical properties of stones are putting them in their drinking water. I found this alarming. 
     I look forward to your response! Thank you for your time.
     Thank You,
- Stacey S.
 
 
 
A: This is a VERY important query, and kudos to you for asking - and for your  determination to protect your unborn baby.

YES. There are minerals that are really dangerous: realgar and orpiment have mercury in them, for example. You can look up Minamata Syndrome to get an idea of how bad these could be to a fetus: https://en.wikipedia.org/wiki/Minamata_disease 

YES. There are various forms of asbestos that kill - literally. My father died a premature death from lung cancer. The biopsy showed that there was asbestos in his lungs, ultimately traced to dust in the basement of his apartment building in San Francisco where he kept his bicycle. The pipes had been insulated with spray-in asbestos in the 1950's when the building was originally constructed. I'd be willing to bet that the workers who blew in that insulation preceded him.

POSSIBLY. Pyrite (FeS) is a mineral that will oxidize in the atmosphere. The bright shiny mineral faces will eventually dull and then go brown. The smell you describe is probably H2S, normally not toxic in small amounts (the smell warns us to get away - this is common around volcanoes I've worked in). My concern is that there are other sulfides that are often naturally associated closely with the pyrite, including cadmium and arsenic sulfides. These are very poisonous.

You are probably safe handling gemstones and semi-precious stones such as citrine, zircon, beryl, and amethyst - these are typically hard minerals that do not interact much with the environment nor degrade with time, which is why they are valued in the first place. 

I would encourage you to think more about a high-quality respirator when in a dusty, mineral-laden room. Inhalation is probably a more serious threat than getting the stuff on your hands... unless (like me) you always have an itchy nose and rub it frequently. Here is a website that will get you started on the various kinds of respirators out there (they run the gamut from the kind your dentist uses to serious industrial equipment): https://www.osha.gov/OshDoc/data_Hurricane_Facts/respirators.pdf 

Putting stones and gems in drinking water also boggles MY mind. A diamond will not react, and most semi-precious stones won't either... but everything else WILL react with water to some degree, especially if the water's slightly acidic (think Coke or Pepsi for acidic fluids). Putting crystals on your body is silly enough... now imagine bright yellow or red minerals in your drinking water!

I hope this helps. I personally love rock shops and as a geophysicist visit them whenever I can. I DO wash my hands after I leave one, however. 
~~~~~



Monday, April 9, 2018

Red Rocks and Green Rocks?

 Some questions begin with a profound basic misunderstanding - but people are still trying to make sense out of their world, so I am grateful that they even ASK questions.
Q: At the age of 40 I am slowly figuring out geology just because I'm curious. 
     One of the things that caught my attention in Dr. Robert M Hazen's The Story of Earth is that the mantle is green: peridotite, olivine, perovskite, etc. That surprised and delighted me, because introductions to Earth science tend to show the Earth in cross section with a lava-colored mantle and core. 
     But when lava erupts, it is usually reddish orange. What happened to change it?
     Is it interaction with water from subducting slabs of ocean floor? Is it because repeated melting has allowed some of the heavier elements to sink away instead of reaching the surface, changing magma's chemical composition? Has it oxidized, in which case the Moon's maria and other airless objects in the solar system might've been green when they were molten? Or is the lava that erupts on the surface  from some other source than the mantle? 
     Thanks for answering our questions. An answer I got from you many years ago helped start my geological journey (I asked whether there could've been continents on the other side of the planet from Pangea that had subducted; you explained that continental rock is less dense than ocean floor so it doesn't subduct. Hazen's book helped me understand WHY it's less dense.)
Regards,
- Ellen B
A: Good on you for actually thinking about these sorts of things.
    SOME mantle-derived rocks are green at the surface because they have significant chlorine content. However, Kimberlites, the long tubes that reach down to 100+ km depths and bring diamonds to the surface of the Earth in places like South Africa, South America, and Arkansas, are famous for being blue in color. It just means different minerals (like chrome diopside) dominate in Kimberlites. Many other mantle-derived rocks are black or gray - and often weather to brown, hence the origin of the name for one rock-type: dunnite, after the color dun originally used to describe certain beige-colored cows. 
    These colors are all what you see at ambient temperatures that exist at the surface of the Earth. However, the deeper you go into the Earth, the higher the temperatures are - this is the geothermal gradient. It's sort of like a biscuit coming out of the oven: the outside quickly cools and chills to a crust, but bite into it too soon and the inside will burn your mouth.
    When you see a red or yellow color in magma, it's because of the TEMPERATURE. This is black-body radiation, a basic physics principle. I'm attaching a photo of me next to what we informally called the "Cookie Monster" in Hawai'i. 

    The black-gray structure is a Hornito - basically a lava splatter-cone. The glowing "mouth" is a Skylight - a hole broken into the top of a lava-tube. We have used a police speed-gun to measure the speed of the lava running past and beneath this skylight: it was moving at 40 km an hour (25 mph). The whole thing collapsed about a month after that photo was taken, by the way - not a good place to be standing.  The grimace on my face is because the air temperature where I am standing was above 60 C (140 F). That blue cloud to my right is H2S gas, which engulfed me just after the photo was taken. My gas mask was on me at the time - but not adjusted to my face - and it turned my nose and throat mucous membrane fluids into sulfuric acid.     
    Translation: my nose and throat felt like they were on fire, and I took off running to get away from the cloud. 
    The colors you see correlate with temperature: red is centered around 4,000 K and yellow is centered around 6,000 K. You may have seen the dull red in a toaster: same thing is happening.
    If you could actually "see" rocks at the 30 - 50 km depths where this lava arose from, they would be yellow or even blue-ultraviolet at deeper depths.  
    Hope this helps you "see" (understand) the different reasons for rock colors. 

~~~~~

Tuesday, March 13, 2018

Who Is Most Guilty?


There has been a lot of Sturm und Drang about Climate Change (previously called "Global Warming" until a US Senator threw a snowball in session to make fun of the term). There has also been a lot of blame laid: (1) for why Climate Change happening (and it really is), and (2) who is still a <stuck-in-the-myth-supporting-Mesozoic> Climate Change Denier? 

Q:To what extent is the Western World having an effect on climate change compared to the rest of the world through their Green House Gas emissions?
God Bless.
- Patric P

A: By what you call the "Western World" - I will assume you mean Europe, North America, and Australia.

Greenhouse gas emissions USED to be disproportionately large from these Developed Countries. Now there are vastly increased - and growing - emissions from the so-called "BRIC" countries (Brazil, India, China).  Coal burning in East Asia and South Asia are causing massive air-quality crises in Beijing and New Delhi as I write this. 

The short answer: we are all guilty of wanting to live a middle-class lifestyle. However, the Guilt Coefficient is shifting even as this is being written.

There is another factor inadvertently adding to everyone's "lifestyle guilt," however.

To understand this, keep in mind that methane (CH4) is a far stronger greenhouse gas, perhaps up to 47 times more effective than CO2 in storing heat. As Developing Countries vie for more animal protein in their diets, the contribution of methane from pigs - and especially cattle - has dramatically increased, and China certainly leads in this growth. Basically, this is animal flatulence, and one cow can emit enough methane to fill three file cabinets in one day. Interestingly, this correlates rather closely with the increased mixing of flu viruses caused by many different animals (ducks, chickens, pigs, cattle) being kept in close proximity with humans. This is a double consequence of our common preferred lifestyle.

There is another factor, however, that may soon come to dominate all the others:

Methane clathrates (also called methane hydrates) dwarf known hydrocarbon reserves on land. These are truly vast quantities of methane frozen in ice in the sub-seafloor below about 300 meters water depth. Any future contribution from these methane clathrates to climate change is THE big unknown here. There is a strong likelihood that rising global temperatures will suddenly lead to a tipping point, and free this trapped form of carbon into the atmosphere. Likewise, a vast methane release could also come from a thawing permafrost in and near the Arctic Circle. The result of both is potentially an explosive increase in greenhouse gases in the Earth's atmosphere. 
 
If you want to get ahead of the curve, do NOT buy beach-front property, and consider moving to the Canadian prairie provinces. 

~~~~~

Friday, February 9, 2018

Is Water Wet?





Sometimes a really obvious answer comes up unbidden to a query. In the response below I had to throttle back my Inner Scientist from wanting to strangle certain abusers of social media. Facts are NOT the same as Alternative Facts. Internet Foo-Foo is NOT truth. Much of it represents all the bad consequences of the 1st Amendment to the American Constitution - without any redeeming good.

Q: So on social media there’s been a huge debate on whether water is wet or not. I believe water is not either wet or dry. So is water wet?

- Kacie M

A: This is akin to Medieval arguments about how many angels could dance on the head of a pin. In other words, it's a pointless issue. Water is water. Wet means something has water on or in it in all versions of the English language that I am familiar with. I did a cursory look and did not see a "huge debate" on social media about water being wet or not. 

Social media should NEVER be considered a source of meaningful information, as there is no vetting, no peer review of the content you see there. People make up "Alternative Facts" and post them to social media, and if it's done with flashy visuals, some weak-minded and poorly educated people might take this stuff as fact. Don't YOU fall into that old make-up-a-fact trap. That's what humanity fought its way out of the Middle Ages to get away from. Your smart phone doesn't work because of some made-up fact about electricity.