Tremors cause work stoppage at sinkhole

Another round of elevated tremor levels halted work Monday at the surface of the Assumption Parish sinkhole at least until Tuesday morning, parish officials said.

Seismic monitoring again detected an increase in the number of “very long period” events, parish officials said Monday. The tremors are linked to gas or fluid movement under the more than 13-acre sinkhole between the Bayou Corne and Grand Bayou communities.

The sinkhole is believed to have been caused by the failure of a Texas Brine Co. LLC salt dome cavern last year. About 350 residents have been under evacuation orders for nearly eight months.

Experts also suspect that the failure caused the release of oil and gas from deep underground toward shallower subsurface depths, as well as to the surface.

John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness, said he was working on the sinkhole Monday morning and saw on its north side water movement known to indicate the tremors.

A later check of seismic monitors by experts working for the state Office of Conservation found the tremors were increasing, leading to the halt in work at about 11:30 a.m., Boudreaux said.

A previous round of tremors late last week led to work on the sinkhole being halted for a day, Boudreaux said.

The tremors sometimes have been followed by the edges of the sinkhole collapsing and burps of gas, crude oil and debris.

Since mid-March, the tremors have been cycling up and down at a quicker pace than months ago. Conservation officials have attributed the change in pace to the cavern getting close to being filled with rock from outside the salt dome.

Conservation officials said in a statement Monday the tremors are located, as in past weeks, under the sinkhole and near the failed Texas Brine cavern.

Another, nearby Texas Brine cavern, for which structural concerns have recently been raised, continues to show no sign of being affected by the tremors, Conservation officials said.

Officials said the area is under constant monitoring.