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About 25 trees fell into the Assumption Parish, La., sinkhole and officials say a new crack formed Monday night in a well pad south of the lake-like slurry hole.
The Advocate reports experts working for the state Office of Conservation believe the collapse and cracked well pad are linked to now-calmed seismic events from late last week.
Because of that connection, agency officials said the discovery did not halt work around the sinkhole and the area remains in emergency officials’ lowest “alert” status.
Parish officials also estimated that the edge collapse, or slough-in, probably bit off a quarter-acre from the formerly 13-acre sinkhole’s southeastern edge.
The sinkhole is located in swamps between the Bayou Corne and Grand Bayou communities and has required the continued evacuation of more than 350 people in those areas.
A failed Texas Brine Co. LLC cavern in the Napoleonville Dome is suspected of causing the sinkhole and related consequences. The cracked surface pad had been used for the original access well to the failed cavern, Oxy Geismar No. 3.
Early on Friday, experts detected an uptick in “very long period” tremors, a type of stretched-out seismic event, that have been linked to fluid and gas movement underground.
The tremors were detected under the sinkhole and around the failed Texas Brine cavern.
Past increases in tremors sometimes have preceded slough-ins and burps by the growing sinkhole.
The edge collapse happened roughly opposite from a nearly 1-acre slough-in on the western edge of the sinkhole that followed other tremors earlier this month.
That earlier slough-in, combined with other measurement changes, had boosted the sinkhole’s area to 13 acres.
The new crack is in an out-of-use ramp connecting the well pad to the sinkhole. The crack is parallel to the sinkhole’s southern edge.