Work at the massive Assumption Parish sinkhole was stopped Sunday after scientists detected seismic activity in the area, parish officials said.

Scientists noticed several instances of subsurface activity early Sunday morning in the area around and below the sinkhole, according to a blog posted on the Internet by the Assumption Parish Police Jury.

Personnel near the site also observed surface movement on the western side of the sinkhole, the post says.

The monitoring alert status at the sinkhole was raised to Code 3, meaning all work inside and around the sinkhole had to be halted, the post says.

Code 3 is the highest alert level in the system being used to describe levels of seismic activity at the sinkhole, according to the Police Jury blog.

The notice about the halted work was posted on the Police Jury blog at 1:50 p.m. Sunday.

The sinkhole was discoveredon Aug. 3 near the Bayou Corne and Grand Bayou communities. About 350 residents remain under evacuation orders.

Scientists have said they believe a failed salt cavern belonging to Texas Brine Co. LLC of Houston caused the sinkhole. The scientists said the failed cavern was mined too close to the Napoleonville Salt Dome’s outer face and eventually underwent a sidewall collapse, leading to the sinkhole’s formation.

Sunday’s seismic activity appears to be limited to the sinkhole area, the Police Jury blog post says.

The activity has shown no impact on a second Texas Brine cavern nearby, whose structural integrity has come into question after tests showed the cavern was closer to the Napoleonville Salt Dome’s outer face than previously thought, the post says.