2.5 Mile Deep Hole Drilled Into San Andreas Fault

iandoh writes "Cool research: Geologists at Stanford University and the US Geological Survey have drilled a 2.5 mile deep borehole into the San Andreas fault. They've extracted over one ton of rock from 2 miles down, and they'll be installing sensors down the length of the borehole."

Comments

Re:Only 2.5 miles?

[Harmonious Botch]

A quick google revealed the following:

The deepest oil well penetrates a mere six miles (ten kilometers) into the crust (the center of the Earth is about 4,000 miles [6,000 kilometers] deeper). Russian scientists dug the deepest hole on the planet in Siberia, but bottomed out at about 7.5 miles (12 kilometers) below the surface. The Mohole project, a 1950s-era U.S. plan, called for drilling a hole 25 miles (40 kilometers) down to the Mohorovicic discontinuity, the boundary between the hard rocks of the crust and the gooey mantle. Sadly, the only discontinuity Mohole ever encountered involved government funding.
It gets harder and harder to drill deep into the Earth because rocks get softer and softer. Brittle at the surface, rocks become plastic at depth, and the pressure caused by the weight of the overlaying crust--about 52,800 pounds per square inch (3,700 kilograms per square centimeter) at a depth of ten miles (16 kilometers), says drilling consultant William Maurer--collapses deep wells, making further drilling impossible.

Re:WTF?

[Xeth]

In Sid Meier's Alpha Centauri (a spiritual branch from the Civilization series, which I consider better than any of the Civ proper games that followed it), thermal boreholes are terrain improvements that provide +6 energy and minerals (a great deal by the game's standards).

Re:Lex Luthor is Pleased

[Zymergy]

That's Mr. Zorin to you! http://www.imdb.com/title/tt0090264/

Re:Only 2.5 miles?

[E 99]

I suspect that they were lying to you to prevent panic. Mines are a favored place to study earthquakes. Indeed, being in a mine probably gets you closer to the epicenter, as most eathquakes are centered miles below ground.

Yes, being a couple km down gets you probably closer to the epicenter. But since the weight pressure on the rock increases linearly with depth, it is reasonable to think that the movement in earthquakes decreases linearly with depth, until it reaches whatever movement was at the epicenter.

Imagine if you took a large compression spring, held it vertically from the bottom, placing a rock on top. Any sudden movement you make with your hand (the epicenter), will result in an amplified oscillation of the rock (the surface), with linearly smaller movements along the spring. IANA earthquakeologist, but it seems to me like an roughly appropriate model.

Re:Only 2.5 miles?

[ShatteredArm]

Actually, their drill began melting. Heat is the biggest obstacle to drilling further than 7 or 8 miles into the earth.