BATON ROUGE, La. (AP) - Tremors recorded in Assumption Parish since late May could explain why a brine cavern failed and caused a massive sinkhole that prompted more than 100 evacuations nearby, officials said Tuesday.
That assessment came from the Texas Brine Co., a Houston-based company that plugged and abandoned the cavern in 2011. The company harvests brine - water saturated with salt - which is used in industrial manufacturing.
But officials at the U.S. Geological Survey say the cavern's failure caused the tremors - not the other way around.
Texas Brine Co. spokesman Sonny Cranch said earthquakes recorded near the Napoleonville salt dome two months before the sinkhole appeared could have damaged the abandoned brine cavern. He noted the tremors concentrated around the sinkhole a few days before it rapidly expanded from a few feet of muck to an acre of sludge that swallowed cypress trees.
"The conclusion at this point is that the damage could very well have been caused by seismic activity that's been going on," he said.
Federal officials disagree. William Leith, coordinator of the earthquakes hazards program at USGS, said that the earthquakes are rare in Louisiana and that the vibrations in Assumption Parish did not lead to the cavern's damage or the sinkhole.
"We believe that the tremors are a result of the collapse of the cavern," he said.
Experts brought in by Texas Brine believe the tremors originated thousands of feet away from the face of the dome and at a substantial depth, Cranch said.
Cranch said a tool used to measure the depth of the cavern bottomed out 1,300 feet higher than anticipated. The cavern was last measured when it was abandoned.
Cranch said the presence of the material hit by the tool indicates the cavern failed.
"That material should not have been there. But the debris, the material at the bottom of the cavern does speak to damage," he said.
Parish officials also say they aren't buying the explanation that tremors caused damage to the brine cavern and are waiting for an official explanation from scientists.
"Who's to say the breach in the salt dome didn't cause the seismic activity? It's just questionable. We're not ruling anything out at this point," said Assumption Parish Police Jury spokeswoman Kim Torres.
Around 150 homes between the Bayou Corne and Grand Bayou communities south of Louisiana Highway 70 South were evacuated after Gov. Bobby Jindal declared a state of emergency in the parish when it appeared the slurry area was expanding.
Several weeks before the sinkhole emerged, residents had also been reporting natural gas bubbling in nearby waterways. Parish officials say aerial photographs taken Saturday indicate the area is more than 400 feet across and 100 feet wider than it was a month ago.
Cranch said Texas Brine will continue to provide weekly housing assistance checks to the evacuated residents.