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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."
Modern oil rigs don't drill into one of the world's largest fault lines. This depth will give a very broad understanding, topologically the distribution of vibration analysis, fracture mechanics, etc., etc.
Models will be developed to study and help with how the Earth expands and contracts.
Heh, if an oil company *did* dig this deep into the San Andreas Fault, I'm *sure* they would be applauded for the scientific discovery they've facilitated...
Apology to Ubuntu forum.
My favored culprit for drastic friction reduction during faulting is lubricating Silica Gel; finely crushed quartz in the active fault zone reacts with water forming fluidic silica gel. There is excellent laboratory evidence of silica gel lubrication in simulated fault zones (see Mineral Gel May Reduce Rock Friction to Zero During Earthquakes, http://www.nsf.gov/news/news_summ.jsp?cntn_id=100325. All that is needed is field evidence, and I think I have it.
Last summer I took a guided tour down into a hard-rock mine shaft several miles deep here in California. One of the questions that was asked was what happens if there is an earthquake and people are in the mine. The answer surprised me: they can't feel earthquakes down there, so the effect is nil.
Apparently, we were told, the destructive force of earthquakes is carried along the upper couple hundred feet of the surface. I am reminded of a body of water that has waves and turmoil on the surface but which is quite calm below the surface.
My guess would be that the sensors don't go any further down because they don't need to.
from iopd.og: Hundreds to thousands of small to moderate earthquakes per day are recorded in a typical deep mine; the strongest may reach an intensity of magnitude 5. Given that many of these earthquakes are controlled directly by the mining activity, their location, timing, and magnitude can be forecast, and instruments can be installed at sites where earthquakes of interest are predicted to occur. The mine infrastructure provides access to the earthquakes' source region and allows three-dimensional mapping of the fault zone. It also allows installation of a three-dimensional array of instruments 1-100 m from an anticipated hypocenter to monitor fault activity before, during, and after an earthquake. Most expected earthquakes exhibit a moment-magnitude range (-2 to 4) that bridges the scale gap between laboratory experiments and tectonic earthquakes in the crust. The mine infrastructure provides an opportunity to investigate the effects of fracturing during earthquakes on fault fluid, gas chemistry, and microbiological communities. These promising conditions have led to the building of an earthquake laboratory in the TauTona gold mine in January 2005 as part of the DAFSAM-NELSAM project From the Southern California Earthquake Center: Northridge earthquake had a hypocentral depth of 18 kilometers (11 miles), deep for a California earthquake, but considered shallow compared to other regions. ( In California even the earthquakes are shallow. )
An interesting map is at http://seismo.berkeley.edu/istat/ex_depth_plot/
Everyone seems to think that, but given that the area in question is up to a mile above sea-level, none of the land you buy before the lithoforming will actually be "waterfront". The best you can hope for is "ocean view."
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