Officials are figuring out if a 4.5 magnitude earthquake triggered an explosion at a fuel storage facility in the San Francisco Bay Area that started a fire and trapped thousands in their homes for hours because of potentially unhealthy air.
The earthquake struck about 15 miles (24 kilometers) southeast from the NuStar Energy fuel storage facility in the Bay Area community of Crockett 15 hours before the Tuesday fire that consumed thousands of gallons (liters) of fuel. Aftershocks in the same area were still being felt Wednesday, including one with a 3.4 magnitude.
State and local inspectors were investigating the fire that shut down the facility, which according to the company has 24 tanks capable of holding more than 3 million barrels of different kinds of fuels.
Emergency sirens blared and a column of thick black smoke that could be seen for miles prompted Contra Costa County public health officials to order people in Crockett, neighboring Rodeo and part of Hercules to stay inside with fans and air conditioners off and to seal their windows and doors with tape or wet towels.
The orders, which affected some 12,000 people, were finally lifted later Tuesday night after it was determined that the air levels were safe.
"Please open your doors and windows to air out buildings and homes. You can resume normal activities," said Ellen Dempsey with the county's hazardous materials program.
The fire began at about 2 p.m. at the tank farm, one of several refining and fuel storage facilities in the Carquinez Strait, a major shipping thoroughfare and a key oil hub.
Video footage of the fire showed flames leading up to an explosion so strong it blew the lid of one of the tanks high into the air.
The fire badly damaged or destroyed two tanks containing about 250,000 gallons of ethanol, a gasoline additive.
About 200 firefighters fought the flames with foam and water, trying to prevent it from spreading to other tanks containing jet fuel and ethanol. They would knock down the flames but they kept reigniting in the spilled fuel.
The fire was finally contained at about 9 p.m., fire officials said.
Fire crews also doused a 14-acre fire that flared in grass next to the tanks.
No injuries were reported but a contractor at the facility had to shelter in a culvert until he could be rescued, fire officials said.
Officials said they did not immediately know the cause of the fire and whether there was any connection to a 4.5-magnitude earthquake Monday night centered in the East Bay city of Pleasant Hill, north of Oakland.
That quake caused malfunctions at two nearby oil refineries operated by Shell and Marathon oil, Randy Sawyer, Contra Costa County's chief environmental health and hazardous materials officer, told KQED News. Some equipment at the Shell refinery was temporarily affected by the quake, spokesman Ray Fisher said.
The NuStar facility is close to Interstate 80, one of the busiest highways in the San Francisco Bay Area, which officials shut down Tuesday afternoon, causing massive backups at the height of evening rush hour. The freeway finally reopened Tuesday night.
A resident of Rodeo, Gabriel Iturbe, sat in bumper-to-bumper traffic as he tried to get home to his teenage son, who was home sick when he called his father to report a loud explosion.
"It literally rocked the house and then soon after, he heard what sounded like a jet plane," Iturbe said, speaking from his cellphone in the car as he looked at "thick, black smoke." He said he was trying to reach his son and take him out to a less smoky location.
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