Embers cause of massive Clayton Fire's rapid spread
BERKELEY, Calif. (KGO) -- This is the second time in a year that a fire in Lake County has spread to cause such destruction in such a short period of time.
PHOTOS: Crews battle massive Clayton Fire in Lake County
In the first few hours, dozens of homes and buildings had already burned to the ground. Not swallowed up by a wall of flames, but in most cases, ignited by an ember.
"A spot fire literally starts with a 1-inch flame length. It's tiny. It smolders for awhile, ignition, flame and then it can move into a house," explained Scott Stephens, a professor of Fire Science at U.C. Berkeley.
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Professor Stephens says Lake County is rich in a sort of plant life called chaparral, a dense shrubs with leaves and twigs that can easily turn into embers.
"There are huge areas of chaparral around this fire, and chaparral under a bad day will burn 100 foot flame lengths," he said.
It happened in last year's Valley Fire in Lake County.
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"If you're in an ember storm sometime, it literally feels like you're in a thunderstorm. Big thunder drop sometimes hitting you, an ember storm is just like that. Thousands of burning embers coming down, all at once," explained Stephens.
The same happened in the Oakland Hills in 1991, which was also an ember-driven fire.
The plant life in the East Bay is different from Lake County, but the danger is similar. Instead of leaves and twigs that become flying embers, the eucalyptus trees here shed long strips of what's called ribbon bark.
"Almost like a small airfoil, you put some heat on that and burn it and throw it into the air, it has this incredible ability to go aloft and move," said Stephens.
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Flying bark is blamed for carrying the fire across Highway 24 and igniting houses in the Oakland Hills Fire.
Professor Stephens says that fire inspired change.
"You look at the homes that were constructed, you have to say that they were really been done a lot better. They have stucco, they don't have combustible roofs," he said.
He adds that fire resistant roofs and siding are the biggest factors in whether a home survives. Many East Bay homes still don't have them.
"If your roof is combustible, your chances of surviving an ember driven fire, probably about zero," said Stephens.
RELATED: Bay Area fire departments sending strike teams to fight Clayton fire
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