Thursday, June 18, 2015

Basalt wool inspired by Pele


-Alison


There are many ways that we can learn from processes in nature. I study volcanoes to understand how they work, but we can also watch volcanic processes to learn how to make neat things that are practical like basalt fiber or basalt wool. 

Problem solving for experiments means having the right tools.
Never underestimate your need for tape.






 
When I started my postdoc I never expected how much shopping it takes to make an experiment. I spend a good quarter of my time shopping for materials (natural rock, ping pong balls), tools (from conveyer belts to thermal cameras), and shipping (how to get these things to rural New York). I also spend some of this time on the phone, or in a store, telling a sales person that I will not be using their product the way it was designed and I understand that I will void any warranty, but really I just need to know its voltage, dimension, or stability. This can be quite enlightening, but also distracting.



Lab size lava crucible. Countertop samples make great trivets.





 
My latest distraction is rock wool. We are currently building a furnace to remelt basaltic lava, so that we can test various mixtures of water and magma, mixing speeds, and geometries to better understand how phreatomagmatic (water and magma) explosions work. We will pour the melt into a separate apparatus where the explosions will occur (don’t want to blow up the furnace!) and (surprise!) there are no premade lava catching containers currently on the market. We need insulating materials for any experiment involving hot rock (we are talking about ~1200 C / 2200 F). As we don’t want the melt to lose too much heat during the experiment, and we don’t want to the heat to damage our equipment, we are going to need a wide variety of materials.

We want to make sure that we can use a similar set up again and again, so we don’t want the insulation to interact with the melt, or change the system during the experiment. Through a series of strange searches in my favorite search engine I stumbled across basalt fiber, also known as rock wool. It is an excellent material for fire proofing and frequently used in roofing. What I quickly learned is there is a whole industry for basalt textiles, that’s right, basalt fabric!


Some insulation material after testing it with direct contact with lab lava.

So what I started reading into, instead of the shopping I was actually supposed to do, was learning about what people do with basalt fabric. I really just wanted to know if I could start a fashion trend to not only wear rock jewelry, but basalt hats, or vests (I would start wearing a vest just to say it was made out of basalt).  Mostly the fiber is used to reinforce concrete, sound proofing, insulating from electrical currents and heat. You can actually get basalt curtains, mostly used in industrial environments, by why not try it out in your home?


So how do you get a rock or even a flowing lava like this:
Ooey gooey basalt lava from the East Rift of Kilauea, Hawaii, 2009


To look like this?

Woven basalt fiber by Racingjeff via Wikimedia Commons


The process is surprisingly familiar. Those of you who have enjoyed cotton candy (or candy floss) at a fair have benefited from a similar process. The basalt is melted, much like the sugar in the fluffy candy treat, and then spun to make a light fibers of glass. It’s not unlike fiber glass. You can see a video of just one type of basalt fiber insulation made here.


Fluffy cotton candy aka candy floss by Cyclonebill via Wikimedia Commons.


This process was inspired by a natural process! During eruptions involving basalt, the runniest of the common magma types, a wind can stretch out the melt and make strings of melt that cool quickly to form glassy fibers. This is usually called Pele’s Hair because it was observed commonly in Hawaii, but recently got more attention in Iceland where the Holuhraun eruption produced enough volcanic hair to make tumbleweeds! (video in Icelandic, but its all about the view). The abundance of this hair led to the suggestion of a new name for the eruption Nornahraun, which means witch’s hair lava.
Pele's Hair photograph by D.W. Peterson, via Wikimedia Commons

On a much smaller scale we’ve made a fair bit of this fiber in the lab. It’s a great reminder that when lava cools it forms a lot of glass, particularly at the surface. Sugar is the glass that most people are familiar with, so it’s not surprising when a volcanologist says poking lava with a rock hammer is like playing with taffy.
Lab made Pele's hair. It sometimes even looks like cotton candy!

This stuff is surprisingly resilient, despite being made of glass, but it can be sharp and get embedded in your skin. I’ve learned this the hard way, so you don’t have to.  

My traveling duck wearing a Pele's hair toupee so you don't have to.

Experiments are used to test scientific hypotheses, but they also can test the creativity of a scientist. Much like how nature constantly tests our ability to respond to our environment. Basalt fiber is a great example of taking inspiration from nature to meet an engineering challenge. It also reminded me that there is always something new to learn!  



Friday, June 12, 2015

The volcano rock stars of Kamchatka, Russia

- Janine
I am pretty excited this week. Next week I am flying back to Kamchatka (Russia) for field work. I get to join a team of Russian scientists to look at deposits on Tolbachik volcano which produced a beautiful flank fissure eruption over 9 months, starting November 2012.

Tolbachik erupting on 22 December, 2012. Image courtesy of NASA Earth Observatory.
A common reaction I get when I say I am studying a Russian volcano is some variation of "there are volcanoes in Russia?".

Yes. Yes there are. And they are amazing!

So first off, Kamchatka is the eastern-most peninsula off Russia which sits on top of a subduction zone. Here the Pacific plate moves westward underneath Kamchatka - hence all the volcanic activity.

Here, the Map of Active Volcanoes in Kamchatka and Northern Kuriles shows the current activity levels using the aviation color codes.
Map of active volcanoes of Kamchatka and Northern Kuriles. Note the subduction zone to the east shown by the Kurile-Kamchatka trench. Courtesy of the KVERT website, link given above.
 Alert Levels can slightly vary in different countries, below is the explanation of the Russian aviation color codes. The current elevated Alert Levels can be seen here.


Here is a screenshot of the KVERT Current Activity of the Volcanoes page showing a good selection of 36 of their volcanoes.
36 of Kamchatka's volcanoes. Date corresponds to last updated image.

It is not uncommon to have a few of the volcanoes erupting at the same time. This NASA Earth Observatory satellite image acquired on 2nd April, 2010, shows Karymsky, Bezymianny, Klyuchevskoy, and Shiveluch all in eruption.

NASA Earth Observatory MODIS satellite image of Karymsky, Bezymianny, Klyuchevskoy, and Shiveluch volcanoes on 2nd April, 2010.

Here are a few of the more famous active (or recently active) volcanoes.

If I was going to pick a personal favorite I would have to go with Shiveluch, the northernmost active volcano. Shiveluch produces regular ash plumes and large pyroclastic flows from the active dome that deposit on top of the 1964 debris avalanche deposit - think of the Mount Saint Helens collapse without the lateral blast. Shiveluch is currently undergoing explosive/extrusive dome building activity and is on Orange Alert.

Eruption of Shiveluch on 24th February, 2015. Photo by Yu. Demyanchuk.

Sitting just south of Shiveluch is the Klyuchevskaya group. Klyuchevskoy is one of the Kamchatkan superstar volcanoes, producing long, narrow lava flows and frequent ash emission. Klyuchevskoy is currently on Yellow Alert with gas/steam emissions.

Bezymianny, Kamen, and Klyuchevskoy volcanoes on 15th February 2015. Photo courtesy of volkstat.ru.

Klyuchevskoy volcano on 1st January, 2015. Photo by Yu. Demyanchuk.
Bezymianny gets a bit of attention and is also part of the Klyuchevskaya group. In 1956 Bezymianny produced a similar eruption to that of Mount Saint Helens in 1980, and was one of the reasons why there was concern for a lateral-blast-type eruption. Fun fact - before Bezymianny woke up in 1955 it was largely ignored, which is why Bezymianny is called "no name" in Russian. Bezymianny is currently on Yellow Alert with 'weak activity' continuing.

Eruption of Bezymianny on 1st September, 2012. Photo by Yu. Demyanchuk.

Kizimen is compared a lot to the pre-1980 Mount Saint Helens, with the beautiful classic volcano shape. Kizimen was active from 2010 to 2013 with ash plumes, pyroclastic flows, and lava flows. Kizimen is currently on Green Alert.

Kizimen volcano steaming on 9th February, 2013. Photo by Alexander, Bichenko.
Last year I went on the University of Alaska International Volcanology Field School trip which took me to the active Karymsky volcano (which of course didn't even produce a puff of ash while I was there). Karymsky had a larger eruption in 1996, producing lava flows from volcano (below), and a phreatomagmatic eruption (water + magma = explosion!) in the Academy Nuak vent 6 km away (see Izbekov et al., 2004 for more information). Karymsky has been puffing away since then and is currently on Orange Alert with moderate eruptive activity and the possibility of ash eruptions at any time.

Karymsky volcano, note the thick lava flows.

Any trip in Kamchatka begins in Petropavlovsk, the city of Kamchatka, which has beautiful views of Avachinsky and Gorely volcanoes - both on Green Alert (which I hope to see without cloud cover next week!)

The helicopter trip to the field site - well back from the field site since the way there was complete cloud cover - took us past volcano after big, beautiful volcano.

Zhupanovsky was lightly puffing away. Zhupanovsky is currently on Orange Alert with moderate activity continuing, and ash explosions possible at any time.
Plume from Zhupanovsky volcano.
Closer view of Zhupanovsky volcano.
And we got a pretty amazing view of Avachinsky (left) and Koryaksky (right).

Avachinsky (left) and Koryaksky (right).
There are plenty more volcanoes in Kamchatka due to the position in the ring of fire, situated between Alaska and Japan - both of which have their own long list of volcanoes. You can keep an eye on the current activity through the webcams provided by the Institute of Volcanology and Seismology here. May more photos of the volcanoes and their activity (including most of the images above) can be found here.

Thursday, June 4, 2015

Man Made Maar experiments (the science)

-Alison



Experimental volcanology is a pretty fun sounding job description, but it is also one that isn’t as obvious in terms of what that entails. There are a lot of different specialties in volcanology, and the day to day activities for volcanologists can be pretty diverse. You can describe what I do as making deposits from simplified versions of volcanic processes using experiments to understand what evidence is left behind in the rocks. The simplifications mean that I can study the complex phenomena of an explosive eruption in parts, one or two at a time. Then I relate isolated processes to the deposits they form, which I compare to natural deposits that are the result of anywhere between 2 and 10 different processes. Every volcanic rock you see is the result of whatever process gets it out of the ground, some form of transport and then deposition. After that the deposits can be altered through physical processes like erosion by water and wind, chemical breakdown, collapse if the deposit is on a steep slope, and so on. To get into the nitty gritty of the experiments that I’ve been working on the last few years we need to consider those first three steps of making a deposit. Then, I promise I'll post some photos of the experiments we did this past Monday.

I study volcanic explosions that happen underground when rising magma interacts with some sort of liquid water, typically ground water. The resulting volcano is called a maar, and it forms a crater that cuts down into the surrounding rock, rather than building upward like a classic stratovolcano. Much of the action takes place underground and makes a downward tapering cone of debris called a diatreme. These maar-diatremes share a lot of similarities with kimberlite pipes where diamonds are found. The volcanic explosions that brings diamonds to the near surface so miners can find them did not form the diamonds, but anyone who loves diamonds should consequently love volcanoes. That's another story.


So how do we make our own maar volcanoes? And what do they tell us?


Step 1) Get that stuff out of the ground: ejection! The fact that these magma-water explosions happen underground and not in an open vent like at Stromboli or Kilauea is really important to how material is moved up and out of the volcano to form deposits. To model this in our Man Made Maars (well, woman made maars, but I do love the alliteration) we bury a chemical explosive in a pre-made gravel ‘substrate.’ So here are two big simplifications: 1) we have an explosion and are not studying what makes the magma and water go boom, but instead we are studying the effects of this explosion. 2) The second assumption is that our test material, layers of gravel are a good ‘host’ for our explosions and that we can use the same material over and over. The reason we can use gravel and not hard rock is maar volcanoes are the products of 100s to thousands of individual explosions. So really, once you have one or two explosions the later ones will happen under a bunch of debris, much like our gravel pits. We have done some explosions where we changed the strength of the host material, but you will have to wait to hear about those results as they are being written up by a M
asters student for publication.
Example of the 'substrate' that we make for our man made maars. The explosives are buried at various depths beneath the surface. The different material types help us track the mixing underground and the ejecta at the surface.

What have we learned so far? Our homemade maars have shown us that the size of the explosion and its depth below the surface are very important factors controlling how big the crater will be, how far material will be throw upward into the air, and how far away the material will travel. It is not a one size fits all type scenario at a maar volcano. The size, number and depth of explosions likely changes over time during an eruption. But most importantly, we have learned that only the shallow explosions get material from underground to the surface. Deeper explosions move material around underground and mix up material in the diatreme, taking nice flat layers and making a jumble. When we look at natural maar tephra ring deposits we see that there is material from great depths in the deposits and what our models have shown us is that it take a combination of deep and shallow explosions to make this happen. If you want to read the papers about this here are some links about our experiment results: Ross et al. 2013 and Graettinger et al. 2014*. And the real rocks that help show evidence of this underground mixing by explosions: Lafebvre et al. 2013.


Step 2) How that stuff gets somewhere else: transport. So volcanic deposits are proof that material from the volcano made it out, but the big question is how did it get where it did? The experiments give us a great chance to watch how debris, what I call ejecta, travels from inside the crater to wherever it lands. We get to use lots of high speed video and watch the explosions go forward, and my personal favorite, backward.  This transport happens in a jet of upward propelled gravel and gas. What our experiments have helped us understand is that the nature of the material above the explosion influences the shape that jet will have and the shape influences where the gravel ejecta ends up. If there is nice flat ground above the explosion the jet is really wide and produces a very dramatic jet. However, if it happens under a well formed crater the jet is narrow and focused. This means lots of the ejecta falls back down into the crater. This is an important process because it means that the crater is full of debris throughout the eruption and that future explosions have to interact with the material on top of it.
Transport: material is thrown into the air by the explosion in a jet. The shape of the jet is controlled by depth of the explosion under a surface (flat, cratered, hummocky) and the energy of the explosion.
The more detailed papers on this subject are Taddeucci et al. 2013 and Graettinger et al. 2014.  The angle of the jet also influences the distribution of the deposits. You can read about those inclined jets in Valentine et al. 2015, and another paper by myself soon.

Step 3) Finally the flying debris must come to rest: deposition. If material goes up in a jet, it must come down. A lot of the gravel in the jets falls back down, we call this ballistic emplacement. Where it falls is a result of the shape of the jet, as I described above, but these gravel, dust and gas mixtures can actually do much more before the come to rest. When the jet collapses it is a mix of big particles, small particles and gas. As the big particles land they displace the gas. This gas escapes between the larger particles and can take the smaller particles along for the ride. This expulsion of dusty gas travels outward along the ground as a density current. A density current is a liquid or gas that moves as a result of gravity acting along differences in density. The dusty gas mixture is more dense than the atmosphere, but less dense than the ground. The density difference prevents the dusty gas from mixing with the atmosphere and moves outward. The smaller particles drop out of the current along the bottom and when the current runs low on particles it stops. The deposit formed by the ballistics in the jet is full of a range of particle sizes, poorly sorted, and is controlled by the shape of the jet. The density current deposits are fine grained and are controlled not by jet shape, but by the amount of material expelled during the collapse. These are very different deposits from the same explosion.
Deposition from the jet occurs in two forms. Falling down in a classic ballistic trajectory, or being pushed outward as fine particles and gas escape from between bigger particles during collapse (seen at the end of the loop).
After establishing the influence of such simple variables as the depth and size of the explosion we started to vary other elements of the explosion set up to better understand these existing patterns and look for others.  This past week we wanted to test the influence of the number of explosions in a crater. We did 10 explosions in the same crater. This meant a lot of work collecting ejecta and crater data. So it will take some time to get all the data sorted. The videos take a lot of time to cut down to a size suitable for viewing (or posting). So please enjoy these photos of the deposits and hard work instead!




Ejecta gets on EVERYTHING, including our sensors.

As the crater got deeper, the graduate student helper had to get personal with the crater and crater bridge.

The last explosion of the day! We've now had over 63 individual 'eruptions' of man made maars.

This camera was on a flag pole. There may be some interesting views of the jets from above. Or they may be dirty. We'll have to wait and see.




* Papers mentioned in text can be found via the following links.

Valentine, G.A.; Graettinger, A.H.; Macorps, E.; Ross, P.-S.; White, J.D.L.; Sonder, I.; Döhring, E. 2015 Experiments with vertically- and laterally- migrating explosions with applications to the geology of phreatic and phreatomagmatic eruptive centers and diatremes. Bulletin of Volcanology.  doi: 10.1007/s00445-015-0901-7
Valentine, G.; Graettinger, A.; Sonder, I., 2014. Explosion depths for phreatomagmatic eruptions. Geophysical Research Letters. DOI: 10.1002/2014GL060096.
Graettinger, A.H.; Valentine, G.A.; Sonder, I.; White, J.D.; Ross, P.-S. 2014. Maar-diatreme geometry and deposits: subsurface blast experiments with variable explosion depth. Geochemistry, Geophysics, and Geosystems.  DOI: 10.1002/2013GC005198.
Taddeucci, J., G. A. Valentine, I. Sonder, J. D. L. White, P.-S. Ross, and P. Scarlato (2013), The effect of pre-existing craters on the initial development of explosive volcanic eruptions: An experimental investigation, Geophys. Res. Lett., 40, 507–510, doi:10.1002/grl.50176.
N. S. Lefebvre, J. D. L. White, B. A. Kjarsgaard, Unbedded diatreme deposits reveal maar-diatreme-forming eruptive processes: Standing Rocks West, Hopi Buttes, Navajo Nation, USA, Bulletin of Volcanology, 2013, 75, 8
P.-S. Ross, J.D.L. White, G.A. Valentine, J. Taddeucci, I. Sonder, R.G. Andrews, Experimental birth of a maar–diatreme volcano, Journal of Volcanology and Geothermal Research, 2013, 260, 1