Friday, March 4, 2016

Can you Drill into a Supervolcano to Relieve Pressure?



As recently as February 2016 an article in a prestigious science journal (Nature) raises the question if a nuclear blast will have an effect on a volcanic eruption? I’m continually amazed at the fixation people have with nuclear devices; this “nuclear question” arose during the 2004 Mount St Helens eruption and again during the 2010 Deepwater Horizon seafloor oil blowout. This is a variant on the same theme, but at least doesn’t suggest some fallout-creating experiment. People who think a nuclear device is comparable to the energy released by a volcano just haven't seen a restless volcano up close. They are a whole lot bigger than they seem to be in the films. Mount St Helens is a relatively small volcano, yet it still took me nearly 6 hours to walk out of the center crater.

Q: So I am watching this tv show (What on Earth) that NASA scientists have found a super volcano that has a potential to explode in a relatively near future in Italy. I'm super curious about a lot of things, but I won't waste your time. Whether if it's true or not, my question(s) is(are): Would it be possible to hypothetically drill into a deep caldera to release pressure on a magma chamber? I get that the chamber is quite a ways down and it would cost a FORTUNE, but if a drill was created to do so, would it work? And (if so) would it be a plausible reason for the world to come together to survive? Thanks for your time, I know you guys are busy.
- Jon T

A: A thoughtful question. You are probably referring to Campo Flegri, a 13-km diameter nested caldera in western Italy. However, there are quite a number of much bigger supervolcanoes around the earth, including at least three "owned" by the United States: Yellowstone (mainly in Wyoming), Long Valley (California), and Veniaminof (Aleutians). 

Unless you spent time on a drill-rig, you would probably not realize that even very large ones used for hunting deep hydrocarbons (like the Deepwater Horizon rig) have limited borehole sizes, particularly at depth, where they reach a human body diameter or less. The active magma chamber at Yellowstone is at least 45 miles (70 km) across northeast-southwest (wider at depth), and lies as shallow as 4 miles (6 km). There is a reason for all the geysers and Morning Glory pools: rain and snow-fall seep downward until they reach an upper magma chamber that is estimated to contain perhaps 48,000 cubic kilometers (11,000+ cubic miles) of molten magma. *

Perhaps you can see where this is leading. A single drill-rig would not even be seen in an image that encompassed the entire caldera. Not even all the drill-rigs on earth (if they could even successfully drill down that deep) would have any noticeable effect. The scales are just so many orders of magnitude greater. Think of a fly doing push-ups on the roof of your house. You get the idea. 

There was an experiment years ago to drill through a recent, 100+ meter-thick recent crust in Kilauea Iki crater on the Big Island of Hawai'i. The drill crew kept losing drill bits to the heat, but eventually they got a hole far enough down that a camera above it would catch a red glow from incandescence at some depth below the top of that lava crust. I don’t think they penetrated into the lava. Even if we had giant drills and lots of them, getting a drill bit to a magma chamber is not really possible. And it takes a LONG time to drill even a small hole in cold rock to those shallowest depths.

* Incidentally, the reason volcanologists are not particularly worried about Yellowstone right now is that estimates of crystal content in the magma mush (from seismic data) range upwards of 95%. That means it's very hot, but verging on solid. We don’t rest on this knowledge however. Geologic history tells us that a shot of deeper mantle basalt into the base of that crystal mush can quickly remobilize and prime the whole system for another vast eruption. The last supervolcano-scale eruption was 640,000 years ago, and before that another at about 1.2 million years ago. From our experience, we would first certainly see a ramping-up series of warning signs, including inflation leading to regional ground-tilt, rock-breaking manifested in a seismic swarm with a pattern to it, and the release of unusually large amounts of volcanogenic gases such as H2S and CO2.

Q: Thank you so much for the information! I was extremely excited to see someone replied. I guess I didn't realize our drill rigs were so small -- and the volcanoes so freakin' huge! That's absolutely mind-blowing. I love learning these new things about geology, the planet, space, etc. Science just fascinates me. Thank you for your time!
- Jon

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