Roughly 1.1 million gallons of crude oil spilled from a pipeline into the Gulf of Mexico in November 2023 because operators failed to shut it down for nearly 13 hours after their data first hinted at a problem, the National Transportation Safety Board said Thursday. The NTSB said the leak off the coast of Louisiana was the result of underwater landslides, caused by hazards such as hurricanes, that pipeline owner Third Coast failed to address even though the threats were well known in the industry. “In the years leading up to the accident, Third Coast missed several opportunities to evaluate how geohazards may threaten the integrity of their pipeline.