New theories emerge about R.I. beach blast
PROVIDENCE, R.I. -- A loud boom that knocked a Rhode Island beachgoer out of her chair is still a mystery days later, and with no evidence of an explosive device and few clues in the sand, investigators and scientists are wondering whether this was a bizarre case of nature acting up.
Among the theories that have been floated: some kind of seismic event, or a methane explosion caused by decayed seaweed or other organic matter under the sand.
"I must confess to not understanding this particular unexplained event," said Stephen Porder, associate professor of ecology and evolutionary biology at Brown University. "Everything at this point is entirely speculation."
The blast Saturday at Salty Brine beach in Narragansett was so strong that Kathleen Danise was hurled from her beach chair near the water line and thrown against a rock jetty 10 feet away. Danise, 60, of Waterbury, Connecticut, suffered two fractured ribs and bruises, her family said.
Danise's family says she has vacationed at Salty Brine Beach in Narragansett, Rhode Island, for 30 years, and had experienced no problems there until Saturday. According to Danise's sister, Laura Demartino, another sister who was present at the time of the blast was also injured.
"There was a massive bang and I seen the actual rocks shift and move," Demartino told CBS Affiliate WPRI Sunday. "And I started screaming, 'Get up, get up!' The same time I'm screaming, the sand erupted, threw my sister from there, like a live canon, face-down, unconscious 10 feet away."
Witnesses that morning said they heard a rumbling and loud bang that sounded like a large firecracker, a grenade or a gas explosion, and noticed a sulfur or butane smell.
The blast left behind a rift in the sand and little else.
Crews dug up a thick electrical cable Tuesday at the site of the unexplained explosion, CBS affiliate WPRI reports.
Some of the beach was closed down Tuesday, but most of it remained open with plenty of people taking advantage.
WPRI reports that several agencies were working together to dig up the cable. It was buried a couple feet deep and required an excavator to dig. The Rhode Island Department of Environmental Management told WPRI that both the Coast Guard and the U.S. Army Corps of Engineers were inspecting that cable and the jetty itself. On Monday, National Grid had said the cable wasn't theirs.
Crews ended up cutting the cable into pieces Tuesday and carrying it away.
State Police Col. Steven G. O'Donnell said there was no physical evidence of an explosion, such as charring or debris. Dogs and chemical swipes detected no explosive residue. Officials also determined there was no natural gas line running underneath.
O'Donnell said investigators were looking into the possibility of a shift in the rocks or a seismic event, but environmental officials said late Monday that a seismologist with the University of Connecticut told them there were no seismic events that registered in Rhode Island on Saturday.
Porder, the ecology professor, and University of Rhode Island oceanography professor John King said the blast could have been caused by a buildup of methane underground. King said it's possible decaying seaweed generated the gas.
"If you were to put a cigarette out in the sand, that might actually set it off," King said.
Rob Thieler, a marine and coastal geologist with the U.S. Geological Survey, had another theory about a possible source of methane: estuary sediments, which sometimes cause explosions when they decay. He said scientists have seen evidence of this phenomenon off the coast of Maine.
"The sea-floor surface looks like a golf ball, and these are presumably places where underlying methane produced by estuary sediment has violently escaped," Thieler said.
This type of explosion could happen spontaneously, he said, though having it happen on a sandy beach is rare.
Porder said methane might have built up from organic matter trapped underground when the jetty was constructed.
"You can definitely get an explosion. How you would have that sequence of events on that particular beach on that particular day, I don't know," Porder said.
All the scientists said they had heard of methane explosions happening in nature. But Porder pointed out that it is typically places like swamps or areas in the arctic that produce high levels of methane.
"I've never heard of a methane explosion on the beach," he said.
O'Donnell said investigators are looking at all possible causes, including the rotted-seaweed theory. "Everything's on the table," he said.
Janet Coit, director of the state body that owns the beach, told WPRO-AM on Monday that the agency is talking to U.S. Geological Survey and the engineers who constructed the jetty in the search for an explanation. The jetty is owned by the U.S. Army Corps of Engineers, which planned to visit the site Tuesday, Maguire said.
Coit said she had heard theories about methane or a pocket of air trapped underground.
"At this point, that's just speculation," she said.