Jan 7, 2013 17:31 Sinkhole belches organic material Sinkhole belches organic material Advocate file photo by HEATHER MCCLELLAND -- The sinkhole that emerged nearly five months ago in Assumption Parish swampland adjacent to the Napoleonville Dome already has grown to more than 8.5 acres in size. Seismic studies will be conducted to learn more about the sinkhole and determine its potential for future expansion. Tree trunks, branches, leaves surface in ‘burp’ Bret H. McCormick| River Parishes bureau Jan. 07, 2013 Comments The 8.5-acre Assumption Parish sinkhole, located between the Bayou Corne and Grand Bayou communities, burped this week for the second time in a month, the company cleaning up the site reported Thursday. Sonny Cranch, a spokesman for Texas Brine Co. LLC, said the burp happened either Christmas night or early Wednesday. He said crews have not been able to determine how much vegetation came up after the burp. The previous burp occurred on Nov. 27. The burp, Cranch said, is composed “of decayed leaves, branches and some tree trunks. It is very likely material from a slough-off that occurred a few weeks ago.” Cranch has said the sinkhole’s belching is simply part of its “natural life,” especially following a slough-off where more land was swallowed by the sinkhole. “When trees on the perimeter fall in due to the supersaturated soil conditions, the weight of the dirt around the root structure carries many — not all — of those trees to the bottom,” he said. “As the dirt washes off the roots over time, the natural buoyancy allows some to rise to the surface.” Unlike the previous burp, which coincided with a long-period earth tremor, this one wasn’t due to a tremor, Cranch said. “To our knowledge there was no seismic event connected to this recent occurrence,” he said. “The stuff seems to have just floated to the surface. Most of it was removed yesterday; the remainder today.” The sinkhole, which scientists believe formed following the failure of an underground Texas Brine cavern in the Napoleonville Dome, was discovered south of La. 70 on Aug. 3. Since then, as predicted, the sinkhole gradually has increased in size and has released methane, natural gas and crude oil underground. Assumption Parish officials ordered the evacuation of more than 150 residences in the area on Aug. 3 because of safety concerns, and that evacuation order remains in place.