Authorities say that scientists investigating the cause of a ‘mystery blast’ that injured a woman on a Rhode Island beach weeks ago has been determined.

The cause has been reported as an explosive buildup of hydrogen, which occurred in conjunction with a copper cable beneath the sand that had corroded. The cable had previously been used by the Coast Guard.

The Blaze reported on Friday. about the hydrogen buildup, quoting an oceanographer, Arthur Spivack, with the University of Rhode Islands Grad School of Oceanography:

“All you need is hydrogen and oxygen in the right mixture and it can combust,” he said. “Everything we observed is consistent with hydrogen combustion.”

Coit said they tested the beach for hydrogen on Friday, took 10 samples and hydrogen wasn’t detected.

Previously, the cause of the Rhode Island blast had aroused speculation that some natural occurrence had taken place, which included an idea that decomposition of seaweed beneath the sand might have been the culprit. Others were concerned about a possible act of terror, but officials ruled out an explosive device early on, and had told beachgoers that there was no credible reason to suspect foul play.