Thursday, September 3, 2009

Great article on the earthquakes in the DFW area

Apparently there is something "peculiar going on here in the DFW are that's not going on elsewhere" as said in a recent article from the Texas Observer. Injecting and/or extracting fluids into the ground can cause earthquakes.
Here is one definition of induced seismicity:
refers to typically minor earthquakes and tremors that are caused by human activity that alters the stresses and strains on the Earth's crust.
It's connection to Mining and Extraction of Fossil Fuel:
Mining leaves voids that can alter the balance of forces in the rock. These voids may collapse producing seismic waves and in some cases reactivate existing faults causing minor earthquakes. Natural cavern collapse forming sinkholes would produce an essentially identical local seismic event.

Extraction of fossil fuel and groundwater
Subsidence caused by
fossil fuel (oil and/or natural gas) and groundwater extraction can generate seismic waves and minor earthquakes.

Here is a few paragraphs from the article and the link.

Gas well activities such as injecting or extracting fluids into or from the earth’s crust can cause earthquakes, Stump said, but many other areas of the state have drilling and fracturing without earthquakes.
“There’s something peculiar going on here [in the DFW area] that’s not going on elsewhere,” Hayward says.

The earthquakes near the DFW airport were close to gas wells set up just last year, Frohlich says, noting, “It’s certainly a likely candidate as being related to the earthquakes.”

Though scientists have had less time to study data from this summer’s Cleburne quakes, “it certainly is suspicious,” Frohlich says.

Similarly, some geophysicists with the United States Geological Survey are intrigued by the prevalence of natural gas drilling near the North Texas earthquakes. USGS research geologist Russell Wheeler recalled a situation in the 1960s when the U.S. Army was trying to get rid of some liquid toxic waste on the north side of Denver. The Army drilled a couple miles into the earth and began pumping the fluid in, but the process was halted when earthquakes resulted, he says.

Paul Caruso, a geophysicist with the agency’s National Earthquake Information Center in Golden, Colo., wanted to know when natural gas drilling started in the DFW area.

Told the boom began in 2001 and has accelerated in the past two years, Caruso said, “That’s all I’m going to say about that.”

Is it related to the earthquakes?
“I’m not going there,” he said, and suggested looking up “induced seismicity.”

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