Arkansas Earthquakes decline since hydrofracking injection wells closed.

LITTLE ROCK, Ark. (AP) — The number and strength of earthquakes in central Arkansas have noticeably dropped since the shutdown of two injection wells in the area, although a state researcher says it’s too early to draw any conclusions.

“We have definitely noticed a reduction in the number of earthquakes, especially the larger ones,“ said Scott Ausbrooks, geohazards supervisor for the Arkansas Geological Survey. “It’s definitely worth noting.“

The Center for Earthquake Research and Information recorded around 100 earthquakes in the seven days preceding the shutdown earlier this month, including the largest quake to hit the state in 35 years — a magnitude 4.7 on Feb. 27. A dozen of the quakes had magnitudes greater than 3.0. In the days since the shutdown, there have been around 60 recorded quakes, with only one higher than a magnitude 3.0. The majority were between magnitudes 1.2 and 2.8.

The two injection wells are used to dispose of wastewater from natural-gas production. One is owned by Chesapeake Energy, and the other by Clarita Operating. They agreed March 4 to temporarily cease injection operations at the request of the Arkansas Oil and Gas Commission.
http://www.syracuse.com/news/index.ssf/2011/03/arkansas_quakes_decline_since.html

Note from the earlier story that Arkansas' earthquakes (800 within a 6 month period in a 10 mile area) had progressed from minor to +4 when their science respecting governor put a halt to activities from just TWO wells, & new wells in the area.

Pennsylvania will have estimated 5,000 wells.

On edit: Just read that there were over ONE THOUSAND quakes w/in 6 months.