02 January 2012

Preventing Large Earthquakes by Intentional Triggering of Small Quakes

Scientists are continuously thinking of ways to try and reduce earthquake power. Some are trying to lessen the friction between colliding plates. They poured water down a fault where two plates were grinding together. The water “lubricated” the fault, letting one piece jerk free with a number of little earthquakes and preventing a large tremor. _EarthquakePrevention
Large earthquakes have killed millions of people, and are a constant threat to hundreds of millions of people living in cities within prominent seismic zones. If there were any possible way to reduce the deadly danger in which these people are living, earth science must investigate the possibility.

Deep injection of fluids into the Earth's crust has the potential to trigger earthquakes, typically small, multiple quakes. Do not confuse this type of deep fluid injection with fracking for oil or gas. The two things are not the same at all.
"Injection induced earthquakes" are NOT caused by hydrofracturing. Injection of fluids for the purpose of waste disposal or well stimulation is NOT "fracking." Injection of fluids CAN induce earthquakes in some circumstances. Hydrofracturing has NOT been found to induce earthquakes. _Injection Induced Earthquakes Reference
An interesting case mentioned in the New York Times of 1 Jan 2012 (yesterday), is a series of small earthquakes in the Youngstown, Ohio, area, associated with the deep injection of waste fluids into the Earth's crust:
An official in Ohio said on Sunday that the underground disposal of wastewater from natural-gas drilling operations would remain halted in the Youngstown area until scientists could analyze data from the most recent of a string of earthquakes there.

The latest quake, the 11th since mid-March, occurred Saturday afternoon and with a magnitude of 4.0 was the strongest yet....a 2.7-magnitude temblor on Dec. 24, showed that it occurred less than 2,000 feet below the well. Because of a lack of data, depth estimates of earlier earthquakes had been far less precise.

... Scientists had suspected that some of the wastewater might have migrated into deeper rock formations, allowing an ancient fault to slip. Similar links between disposal wells and earthquakes have been suspected in Arkansas and Texas. _NYT
Injection-induced earthquakes have been noted in Germany in 1997, in Colorado in the 1990s, in Texas, and Arkansas.

This reference website contains over 130 references to reports of injection associated quakes. The association between deep crust fluid injection and small earthquakes appears to be well founded. But it is important to note that there is no such association between fracking and earthquakes. Keep that distinction in mind.

Geothermal power at the Geysers in Lake County, California, has been associated with thousands of tiny earthquakes above magnitude 1 since 1975 when the resource was tapped.

Earthquakes are triggered by a number of different things, including the construction of hydroelectric dams.
Depth of the reservoir is the most important factor, but the volume of water also plays a significant role in triggering earthquakes.

RIS [Reservoir Induced Seismicity] can be immediately noticed during filling periods of reservoirs.

RIS can happen immediately after the filling of a reservoir or after a certain time lag.
It would be best for humans to invest in the best accelerated research possible to clearly and unequivocally define the risks and benefits of small scale induced seismicity. One of the best ways of doing this would be for seismic scientists to work closely with deep drilling enterprises which also involve the deep injection of fluids into the earth's crust. By piggy-backing onto economic activity which is already being done, seismologists can increase the detail of their seismic maps, and can also collect abundant data on the impact of deep crustal fluid injection into different fault configurations.

The risk of causing small earthquakes associated with deep geothermal drilling for enhanced geothermal power, and in CO2 sequestration injection into the crust, are both real -- although perhaps minimal. Whether such injections will serve to reduce the risk of later larger earthquakes is something that needs to be determined.

One thing is very clear, however: While lefty-Luddite greens of the energy-starvationist persuasion are screaming about the unlikely possibility that fracking might conceivably cause small earthquakes, the very real possibility that deep injection CO2 sequestration will likely cause small quakes is ignored by the same activists.

If there is a way to prevent large, destructive earthquakes by triggering multiple smaller quakes in a prophylactic manner, such technologies should be studied very carefully and expeditiously.

Part of this article was taken from a previous article at Al Fin Energy.

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