Tuesday, March 22, 2016

When Did Mankind Start Studying Geology?



History always helps us view complex things in a wider perspective that helps us to understand them better. The history of geology is no exception.

Q: When Did the Study of Geology Start?
- Christian C

A: There is a good article in Wikipedia on this, and it begins with "...in the 4th century BC Aristotle made critical observations of the slow rate of geological change. He observed the composition of the land and formulated a theory where the Earth changes at a slow rate and that these changes cannot be observed during one person’s lifetime <in other words, he introduced the paradigm of Gradualism>. Aristotle developed one of the first <evidence> based concepts connected to the geological realm regarding the rate at which the Earth physically changes." In a larger sense, Aristotle was the father of all of the sciences.

Avicenna <Ibn Sena> (981-1037), a Persian scholar, made significant contributions to geology, and Shen Kuo (1031-1095), a Chinese polymath, also contributed the first treatise on geomorphology.

The actual term "geology" was not established until 1751 (by Denis Diderot in his "Encyclopedie"). Some people credit the Scotsman James Hutton with being the first modern geologist. However, William Smith published the first true geology map of any significance (of Great Britain) in 1815. He used fossils and stratigraphy to correlate units all over the country with each other, and made an initial estimate of the age of the Earth as possibly being millions of years old. Charles Lyell challenged the biblical-based Catastrophism of the 17th Century with the publication in 1830 of his book "Principles of Geology." These two are whom I would consider the real first geologists. Darwin, who followed later, was Lyell's first disciple; he carried a copy of Lyell’s book with him on his famous three-year voyage of HMS Beagle.

Since the time of Aristotle, we have had other geology paradigms, including  the more recent Punctuated Gradualism. You can probably figure that out from its title.

Incidentally, I was touched that the Wikipedia article gives credit to my good friend and paper co-author Gene Shoemaker as the father of Astrogeology; Gene was killed in a car accident in Australia in 1996 and I still miss him. 


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