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Hole Drilled to Bottom of Earth's Crust
AtariAmarok writes "A new article is up on LiveScience about a hole drilled into the Earth's crust to explore the layers of our planet's substrate. The hole gets closer to the mantle than any other efforts that have gone before. The hole might reach the "Moho" (division between Earth's brittle outer crust and the hotter, softer mantle) within a few years." From the article: "The depth of the Moho varies. This latest effort, which drilled 4,644 feet (1,416 meters) below the ocean seafloor, appears to have been 1,000 feet off to the side of where it needed to be to pierce the Moho, according to one reading of seismic data used to map the crust's varying thickness."
That's happening all the time on the sea floor, where the plates are slowly separating.
A bunch of lava will squish out, immediatly cool, and plug the hole, and they'll have to start all over again.
Kind of like Cool Hand Luke.
I don't need no instructions to know how to rock!!!!
EOS covered this recent work just recently. The problem with offset drilling is that it does not provide the same informatio as a continuous core. These cores are obtained from 'windows' in previous flows and there is a problem with correlation between boreholes when horizons are not sampled widely. This complicates the historical interpreation and genesis of the oceanic crust.
The demand for advanced drilling technology is one problem with the current Moho sampling efforts. Exploration drilling of the kind used for oil production is not well suited for the work that the ODP is engaged in. Bit designs for the lithostatic loads that these dense rocks develop at depth require a different approach than those used to drill continental sediments buried at depth beneath the ocean.
"Rocky Rococo, at your cervix!"
Unlikely. The Mohorovicic (Moho) discontinuity can be described in a few different ways - either where seismic veolocities have a marked discontinuity, or where a noticable chemical/mineralogical change occurs (can't remember what it is, I'm a geophysicist, not a geologist). What it's not is a boundary between a nice solid crust floating on top of "firey liquid mantle". In fact more accurate terms are lithosphere and asthenosphere, rather than crust and mantle, which basically differentiate between rigid, colder material, and warmer, more ductile rock. The top of the mantle is still solid, but becomes increasingly ductile with depth. Various minerals reach melting point as you go down towards the Core-Mantle Boundary, but basically I think you have to get to the outer core before it's all liquid (mostly iron). In terms of energies, the largest nuclear bomb ever detonated was about 55-60 megatonnes (depending on who you ask), in 1961 by the USSR. The energy released by the great 1960 Chilean earthquake (the largest recorded in the last 100 years) was equivalent approximately to a 2000 Mt bomb. So, setting off a nuke at the moho might temporarily create a small spherical cavity which would probably collapse in on itself, and maybe create some melt, but it's doubtful it would come gushing to the surface as a raging plume of "liquid hot magma". Besides, there have been plenty of underground nuclear tests, and none of those have resulted in a humungous volcano. As yet. The USGS site at http://www.usgs.gov/ is probably a good place to find out more.