Tremors at Assumption sinkhole halt some work
BAYOU CORNE (AP) — A moderate increase in tremors at the 15.1-acre sinkhole near Bayou Corne has prevented work there since Wednesday, Assumption Parish officials said.
They’re not strong enough to indicate another edge collapse and have in the past sometimes dropped from the level they’re currently at rather than increasing, parish emergency preparedness director John Boudreaux said.
The last slough-in and “burp” of natural gas, in mid-April, added about three acres to the sinkhole.
Conservation and parish emergency officials halted work on the sinkhole’s surface. Work elsewhere continued while the micro-earthquakes ranged from 10 to 50 per day.
The tremors and surface slough-ins occur normally as the sinkhole finds its final shape and size, according to officials from the state, the parish and Texas Brine Co., which owns the failed cavern thought to have caused the sinkhole.
Friday marked the ninth month that 350 residents of Bayou Corne and Grand Bayou have been under an evacuation order.
Officials with the Louisiana Office of Conservation said Friday that devices measuring seismic activity have picked up “an increasing trend” in subsurface tremors associated with breaking rock and rock movement.
Scientists think the Texas Brine cavern was carved too close to the outer face of the Napoleonville Dome.
After its side collapsed 5,600 feet underground, millions of cubic yards of rock flowed into it. The cavern continues to fill with material surrounding the salt dome.
Gary Hecox, a CB&I hydrogeologist working on the sinkhole, said earlier that past micro-earthquakes happened at the top of the Texas Brine cavern at 3,400 feet deep and at about 1,000 feet in the caprock on top of the Napoleonville Dome.