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Showing posts from 2015

Explosive dangers at Kilauea volcano

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- Janine

My first AGU Fall Meeting was so full of wonderful science - emergency management exchanges with Colombia to address hazards of lahars (Nevado del Ruiz), volcanic lightning, active monitoring of volcanoes, community preparedness, and all aspects of volcanic activity above, on, and below the surface. I had great conversations with people excited by their work and eager to communicate their work with the AGU masses.

One of the many posters that caught my attention was "Don't forget Kilauea: Explosive Hazards at an Ocean Island Basaltic Volcano" by USGS volcanologist Don Swanson. When I talk to people about volcanology the first thing to come up is usually how cool it must be to study lava flows at Hawaii. Well, I don't study effusive lava flows, I am on the explosive end of the spectrum with dome collapse block and ash flows, and I have not yet visited Hawaii. One thing is obvious, many people I talk to think of the relatively safe (with exceptions) pahoehoe l…

In the Company of Volcanoes at AGU

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-Alison and Janine

The largest geoscience conference happens every year in San Francisco. The American Geophysical Union (AGU) meeting draws more than 20,000 participants from around the world every December. We gather to share our new results, catch up with friends and colleagues, and drink beer. Janine and Alison will both be attending this year. Although we have been to conferences in three other countries together, this will be Janine's first AGU and the first conference in the US where we both be in attendance. Both of us have posters to present on our research, and then will spend the rest of the visit stuffing our brains full of new information and names of new colleagues. If you are going to AGU we'd love you to stop by and chat!

So what sort of topics get covered in a 20,000 person conference? Way more than we could fit in a blog post, but you can get the idea just from our examples.

Alison will be presenting in a session called "Eruptive Processes and Watery Ha…

Not all holes in the ground are the same.

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-Alison


Since I spend a lot of time thinking about holes in the ground, from the ones I make with dynamite, to volcanic craters, I have to spend some time thinking about other mechanisms, both human and natural, that make similar looking holes in the ground. If I want to say anything about volcanic holes in the ground, such as maar volcanoes, I need to know what makes them unique. If I want to recognize just one type of hole in the ground remotely on Earth, or other planets, I need to know more about holes in the ground in general.
Let's start with the largest holes in the solar system, impact craters. One of the most important processes for changing the surface of a planet, or any planetary body (moons, asteroids, etc.) is meteorite impact. There is a lot of junk flying around in space. This junk (rock, dust, ice) runs into other junk and in most cases form impact craters on the bigger piece of rock/ice. These impact craters are really common on planets with no atmosphere, biosph…

Do you live near a maar volcano?

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-Alison

I am always going on about maar volcanoes. So where are the maar volcanoes? These volcanoes are formed by explosions underground occur because magma interacts with water and form unassuming craters. The craters are cut below the ground surface so their outer slopes are fairly shallow, and they are frequently filled with a lake. When there isn’t a large majestic volcano to climb and take fancy sunset photos in front of, it can be hard to get excited about what looks like a little hole in the ground. But remember, they are explosive, it takes a lot of energy to carve a big hole in the ground. I use dynamite to make craters that are only 2 meters in diameter (a tall friend lying on their side). We would need about 10,000 sticks of the dynamite we use to get close to the size of a maar volcano. I have been recently comparing the shapes and sizes of maar volcanoes around the planet. While I knew they were all over the place, I am now better informed on exactly where and how big the…

Flowing rock frozen in time at Inyo Domes, California

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- Janine

What happens when you get really viscousrhyolite (high silica content which makes it very sticky) magma rising to the surface? Well, it either stops, produces a really big bang, or oozes. When it stops below the surface it forms granite, which we see a lot of nearby in Yosemite. A build up of gasses that produces very high pressures can result in an explosive eruption, like certain eruptions that have occurred in the past at Yellowstone and Long Valley calderas. When the conditions aren't right for an explosive eruption, a more quiet 'oozing' of lava occurs at the surface that creates some really fantastic looking rocks! If you want to see a great example of rocks where you can see how they moved, head over to the Inyo domes volcanic chain near Mammoth mountain in California. The Inyo domes are near the edge of the Long Valley caldera, Yellowstone's less infamous cousin, west of the Mono domes chain.

The Inyo chain is a group of rhyolitic domes and flows that…

The eruption is how big? Deposit volume story

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-Alison

It seems obvious to say volcanoes are big, but as with anything in geology size is not immediately obvious. Volcanoes can loom over a landscape, spread ash over large chunks of the planet and even influence our climate-that all sounds big. On the scale of an individual human any eruption is big. They are frequently faster than, slower than (yes both), hotter than and physically larger than a human being. One of the exercises I use when teaching volcanology is focused on understanding just how big, "big" is. We go about this by finding things that we already understand the size and compare them to volcanoes. Like many natural processes (and humans), volcanoes and volcanic eruptions come in all shapes and sizes. If volcanoes only had one size and style of eruption our job studying them and anticipating future eruptions would be much easier.



We need to be able to put a size to volcanoes because it is one way to wrap our heads around the hazards they pose. One of the firs…