Nearly 30 earthquakes struck Oklahoma over an 18-hour period from Wednesday night through Thursday afternoon, including two that measured 4.4 and 4.8 in magnitude on the Richter scale that hit 30 seconds apart, and a third that measured 4.0.

Meanwhile, SandRidge Energy Inc., which so far has refused to comply with orders from the Oklahoma Corporation Commission (OCC) to shut down four wastewater injection wells in the state, had its stock delisted by the New York Stock Exchange (NYSE) on Wednesday due to a low stock price.

According to data from the U.S. Geological Survey, 29 earthquakes of 2.5 magnitude or higher struck Oklahoma over an 18-hour period, beginning with a 2.5-magnitude temblor that hit 3.1 miles east of Edmond at 7:20 p.m. CST on Wednesday, and ending with another 2.5 quake that struck 18.6 miles northwest of Fairview at 1:26 p.m. on Thursday.

The largest earthquakes over the 18-hour time span were a 4.4-magnitude temblor that struck 19.3 miles northwest of Fairview at 10:27 p.m. on Wednesday, followed 30 seconds later by a 4.8-magnitude quake in nearly the same position. A 4.0-magnitude earthquake struck at 2:37 a.m. Thursday, with an epicenter 16.7 miles northwest of Fairview.

On Wednesday, NYSE said trading of SandRidge — which had a ticker symbol of SD — would be suspended immediately, after the exchange’s regulation division determined that the company was “no longer suitable for listing based on ‘abnormally low’ price levels,” pursuant to the exchange’s policies. SandRidge stock closed at 15 cents/share (down two cents/share, or 11.8%) on Wednesday.

In response to earthquakes that hit in November, the OCC’s Oil and Gas Conservation Division (OGCD) ordered SandRidge to shut down four wastewater disposal wells in early December, but the company has so far refused, ostensibly on the grounds that it would be uneconomic for it to do so (see Shale Daily, Dec. 21, 2015; Dec. 4, 2015). In response, the OGCD prepared to take legal action against SandRidge in the OCC’s court system.

A spokesperson for SandRidge could not be reached for comment Thursday.

The OGCD began ordering operators to either shut down or curtail intake volumes at injection wells in March 2015, shortly before scientists with the Oklahoma Geological Survey (OGS) attributed the increase in seismic activity to injection wells targeting the Arbuckle Formation, which closely overlies the crystalline basement (see Shale Daily,April 22, 2015;April 2, 2015). The OGS said the disposal of extremely salty water — a byproduct of oil and gas production, not the mostly freshwater used for hydraulic fracturing (fracking) — is responsible for the quakes (see Shale Daily,Jan. 5).

On Tuesday, the OGS said 907 earthquakes of 3.0 magnitude or higher struck Oklahoma in 2015. Of those, 29 earthquakes measured at least 4.0 in magnitude.