Hurricane Isaac's Eye Wall Expected to Barrel 'Right Over' Louisiana Sinkhole

Aug. 29, 2012 — -- The eyewall of Hurricane Isaac is expected to barrel "right over" Assumption Parish, La., today--the home of a massive sinkhole that has raised fears of expansion and possible explosions from nearby gas-filled caverns.

The eye wall of a hurricane is a band of clouds just outside of the eye, or center, of a hurricane, according to the National Oceanic and Atmospheric Administration (NOAA). The most intense winds and rain happen near the eye wall, making it the most dangerous part of a hurricane.

"The latest update puts the track of Hurricane Isaac right over Assumption Parish," police wrote in a statement.

The area is expecting sustained winds of 60 to 70 mph with gusts at 85 mph, according to the Assumption Parish Police Jury. Seven inches of rainfall are expected.

The 400-foot deep hole measures about 526 feet from northeast to southwest and 640 feet from northwest to southeast. It is in Assumption Parish, about 50 miles south of Baton Rouge.

On Aug. 16, the sinkhole swallowed the boat of two cleanup workers, who had to be rescued from the hole.

Greg Hancock, a professor of geology at the College of William and Mary, said it's hard to predict how the hurricane could affect the sinkhole.

"The fact that we're going to get more rain doesn't necessarily mean that there will be a great collapse of the sinkhole," Hancock told ABCNews.com today, but said it was possible that "getting additional water into the sidewalls of this sinkhole could lead to a collapse in the sidewalls."

Hancock likened the situtation to building a sandcastle on the beach.

"The last thing we want is for the sand to be really wet," he said. "The more water gets added to the sand, the less stable it is."

"There's no reason why this sinkhole shouldn't continue to grow, but I don't know if it'll have anything to do with how much rain they get," Hancock said. "I'd want to keep an eye on it, but I don't think there's a reason to think that there's going to be significant growth to this associated with the hurricane."

A mandatory evacuation of all of Assumption Parish was issued on Tuesday night. Schools are closed Wednesday and Thursday, a midnight curfew is in effect and the sale of alcohol has been banned, according to officials.

A "shelter of last resort" was opened at a middle school, but officials warned, "All evacuees should bring all necessary items such as sleeping bags, pillows, blankets, toiletries, personal hygiene items, medicines, food, water, and personal identification. No cots will be provided."

The sinkhole sits in the middle of a heavily wooded space where it has consumed all of the soaring cypress trees that had been there. Flyover photos show some of the treetops still visible through the mud.

While officials are not certain what caused the massive sinkhole, they believe it may be have been related to a nearby salt cavern owned by the Texas Brine Company.

After being used for nearly 30 years, the cavern was plugged in 2011 and officials believe the integrity of the cavern may have somehow been compromised, leading to the sinkhole, which appeared in early August.

Louisiana's Department of Natural Resources required that Texas Brine drill a well to investigate the salt cavern as soon as possible, obtain samples from the cavern and provide daily reports on the findings.

The sinkhole is on the outside edge of the salt dome where this particular brine well is located.

"There are some indications that it very well may have been connected, but there's just indications," Texas Brine Company spokesman Sonny Cranch told ABCNews.com. "There's nothing concrete that has connected the sinkhole to the cavern."

The exploratory rig is being assembled but parts of it are still being shipped. It could take 40 days for the actual drilling to begin, even with an expedited process, Torres said.

In the meantime, officials and residents are left to worry about the possibility of an explosion.

All of the neighboring natural gas pipelines that were of concern last week have been depressurized and emptied, but the nearby caverns are still causing concern.

One cavern that contains 940,000 gallons of butane is of particular concern, Torres said. It's about 2,000 feet from the sinkhole.

Authorities are concerned about the massive explosion that could result from the butane's release to the surface if the sinkhole were to expand far enough to reach it.

There was bubbling in the water and the sinkhole is near areas where there has been exploration for oil and gas in the past. This would make the presence of low levels of naturally occurring radioactive material (NORM) possible.

The state's Department of Environmental Quality said water samples from the sinkhole showed oil and diesel fuel on its surface, but readings have not detected any dangerous levels of radiation.

"It's not going to get fixed tomorrow," Torres said. "We urge the residents to leave to protect themselves. We have no idea how far this sinkhole will expand or in what direction. We have no clue."