Scientists Solve Mystery of Rhode Island Beach Blast Hydrogen gas built up from abandoned underground cable By Newser Editors and Wire Services Posted Jul 24, 2015 6:04 PM CDT 43 comments Comments Authorities investigate a mysterious blast that threw a beachgoer into a nearby jetty at Salty Brine beach in Narragansett, R.I. (Steve Szydlowski/Providence Journal via AP) (Newser) – A mysterious blast on a Rhode Island beach likely was caused by the combustion of hydrogen gas that had built up because of a corroded copper cable under the sand, investigators said today. Officials have spent nearly two weeks trying to figure out what happened on July 11 at Salty Brine Beach in Narragansett, when witnesses heard a large boom and a woman from Connecticut was sent flying through the air into a jetty. (She survived with injuries.) Police ruled out an explosive device or intentional act, and now scientists at the University of Rhode Island Graduate School of Oceanography say it was caused hydrogen released by the corrosion of an abandoned copper cable that previously was used by the Coast Guard. One researcher explains that hydrogen combustion is about the simplest chemical reaction there is. "All you need is hydrogen and oxygen in the right mixture and it can combust," he says. "Everything we observed is consistent with hydrogen combustion." Scientists tested more than 300 samples of sand and found some pockets with 10,000 times the expected level of hydrogen. Authorities say the area is once again safe. "The beach has been trenched, dug and aerated, and we've got no concerns for public safety," says Janet Coit, director of the state Department of Environmental Management. It's standard protocol for the Coast Guard to leave abandoned cables in place because removing them could disturb the environment. The Salty Brine Beach cables were removed during the investigation.