A lightning strike likely ignited a 2020 wildfire in California’s Sierra National Forest, but the U.S. Forest Service said Friday it could not determine an official cause of the fire.

September’s Creek Fire burned 600 square miles and spread so quickly that hundreds of Labor Day holiday campers had to be rescued by a series of harrowing helicopter flights. All 214 campers were delivered safely.

Investigators did not rule out arson and lit cigarettes as the cause, but said there were no illegal marijuana grow sites nearby that could have started the fire. Forest service officials said an “undetermined” status is not uncommon with a fire this complex.

California power company Pacific Gas and Electric said on Wednesday it would bury 10,000 miles of power lines in high-risk fire zones as a safety measure after its equipment caused multiple destructive wildfires over several years.

The utility, which called the project a multi-year initiative, maintains more than 25,000 miles of overhead distribution power lines in the highest fire-risk zones, or more than 30% of its total distribution overhead system, according to the company.

The move by PG&E comes days after it said its equipment may have been involved in the start of a recent wildfire in Sierra Nevada, according to a filing by PG&E to regulators published on the internet by a San Francisco Chronicle journalist.

Pacific Gas & Electric reported to California utility regulators that its equipment may have been involved in the start of a fire burning in the Sierra Nevada that is threatening hundreds of homes.

PG&E said in a report Sunday to the California Public Utilities Commission that a repairman responding to a circuit outage on July 13 spotted blown fuses in a conductor atop a pole, a tree leaning into the conductor and fire at the base of the tree.

The utility said its system showed around 7 a.m. that the Cresta Dam off Highway 70 had lost power but because of the steep, rough terrain, the worker sent to check it couldn’t reach the area until nearly 5 p.m.

It may have been around 2017 when a true sense of urgency donned on insurers, public officials, residents and regulators in wildfire-prone California, as fires destroyed or damaged more than 10,000 structures in the state, a higher tally than the previous nine years combined.

In terms of property damage, 2017 was the most destructive wildfire season on record in California at the time, with 9,133 fires burning more than 1.2 million acres, and it was after 2017 that the word “mitigation” seemed to appear more prominently and more often in public messaging about wildfires – along with news of warnings about rising homeowners insurance rates, increasing non-renewals, and of course climate change.

A magnitude 5.1 earthquake struck off the Northern California coast late Saturday, the U.S. Geological Survey confirmed.

The earthquake just before midnight was about 12 kilometers west of Petrolia in Humboldt County and 56 kilometers southwest of Eureka, according to the USGS.

The depth was just over 30 kilometers.

Cal/OSHA is cautioning California employers to be prepared to protect workers from unhealthy air due to wildfire smoke.

When workers are at risk form unhealthy air from wildfires, California’s protection from wildfire smoke standard requires employers to take steps such as changing the location of work operations, modifying work schedules or providing proper respiratory protection like N95 respirators.

According to CalFire, there have been over 4,000 wildfire incidents so far in California in 2021 and more than 100 structures have been damaged. Smoke from these wildfires contains chemicals, gases and fine particles that can harm health.

One of the most harmful hazards comes from breathing fine particles in the air (called PM2.5), which can reduce lung function, worsen asthma or other existing heart and lung conditions, and cause coughing, wheezing and difficulty breathing, according to Cal/OSHA.

Aftershocks have hit the region between Northern California and Nevada Friday after a magnitude 6 earthquake sent large boulders rolling into highways and knocked smaller items off shelves.

The quake shortly before 4 p.m. Thursday was centered south of Lake Tahoe near Walker, a rural community of a few hundred households in the eastern Sierra Nevada. It was felt as far off as Las Vegas and San Francisco, authorities said. Days of aftershocks are expected.

California state emergency crews worked overnight and found minor road damage but no significant impacts to infrastructure, said Brian Ferguson, spokesman for the California Governor’s Office of Emergency Services. No injuries were immediately reported.

Firefighters struggled to contain an exploding Northern California wildfire under blazing temperatures as another heat wave blanketed the West, prompting an excessive heat warning for inland and desert areas.

Death Valley in southeastern California’s Mojave Desert reached 128 degrees Fahrenheit on Saturday, according to the National Weather Service’s reading at Furnace Creek. The shockingly high temperature was actually lower than the previous day, when the location reached 130 F.

If confirmed as accurate, the 130-degree reading would be the hottest high recorded there since July 1913, when Furnace Creek desert hit 134 F, considered the highest measured temperature on Earth.

The nation’s largest utility has long vowed to change its reckless ways, but year after year there’s more death and destruction from Northern California wildfires sparked by Pacific Gas & Electric’s equipment.

CEO Patricia “Patti” Poppe, who took over in January as the company’s fifth leader in less than three years, has pledged to shareholders that the future will get “easier” and “brighter.” That vow will be put to the test as California sinks deeper into drought and fire danger increases.

Containment of three big wildfires in Northern California has increased but potential for a new round of winds this week was a concern, authorities said Monday.

Containment of the 39-square-mile Lava Fire at the foot of volcanic Mount Shasta jumped to 71% after minimal overnight activity, Shasta-Trinity National Forest said. Remaining evacuation orders were downgraded to warnings.