Fire on the Fast Track: How the Flames Spread

A combination of Santa Ana winds, flying embers and shake roofs helped a runaway blaze to sweep across more than 12,000 acres of Laguna Beach wilderness and destroy more than 330 homes.

Recipe for Destruction in Laguna Beach

The destructive ingredients: hot temperatures, low humidity, Santa Ana winds and high-density older housing.

1. Driven by Santa Ana winds, a fire reported at 11:30 a.m. Wednesday quickly churns into a blaze roaring through Laguna Coast Wilderness Park. Fed by meadows of new vegetation, flames reach 50 to 100 feet in the air and ground temperature is estimated to be 2,000 degrees.

2. Wind and heat intensity create a cyclone effect that scatters embers in all directions. Wind gusts up to 80 m.p.h., which can carry embers up to a mile away, help start spot fires on shake roofs and treetops in surrounding areas.

3. Treetop fires cause nearby power line transformers to explode, sending fire in all directions. Homes built with wood siding and shake roofs and crowded into small lots with little space between individual structures are particularly susceptible to spreading flames.

4. Efforts to contain fire are thwarted by evacuee traffic, winding and narrow roads, and poor visibility from smoke. At times, water pressure is so low firefighters are helpless.

Clocking the Blaze

Wednesday 11:30 a.m.: Brush fire reported 12:15 p.m.: Fire rages out of control; cyclone effect spreads spot fires in all directions 2-3 p.m.: 35 to 40 Emerald Bay homes burn in an hour 3:15 p.m.: Gusting winds spread fire southwesterly toward downtown Laguna Beach 4:15 p.m.: Parts of Laguna Beach are evacuated 5:15 p.m.: Fire spreads northwest, destroying half of El Moro Beach Mobile Home Park 5:30 p.m.: Embers jump Laguna Canyon Road, igniting brush 30 yards from City Hall 8:15 p.m.: Blaze pushes north; Turtle Rock evacuated 9 p.m.: Onshore breezes push fire back on itself in northeasterly direction 9:25 p.m.: 100-foot flames leap up embankment, endangering Irvine 10:30 p.m.: Firefighters light backfire line at northeast boundary of fire

Thursday Midnight: Low clouds cover coast; winds stop; firefighters hold fire line at Park Avenue 6 a.m.: Fire 60% contained 6 p.m.: Fire 100% contained

Tallying the Damage

Anaheim Hills * 750 acres burned in 11 hours * 31 homes damaged or destroyed * 350 firefighters, 100 trucks and bulldozers * 2 injuries: 1 firefighter, 1 resident * 100% containment

Laguna Beach * 12,000 acres burned in seven hours * More than 330 homes damaged or destroyed * 2,500 firefighters, 75 trucks, several helicopters and air tankers * No injuries reported * 100% containment

Ortega Highway * 12,300 acres burned; fire creeping in northeasterly direction * 20 homes damaged or destroyed * More than 300 firefighters coming from across the country; air tankers and helicopters to start today * No injuries reported * Aiming for 50% containment by Saturday

Weather Update: Light winds and cooler temperatures are expected today. But a high-pressure system is moving toward Orange County and could bring strong winds.

Sources: Orange County Fire Department, U.S. Forest Service; Researched by APRIL JACKSON / Los Angeles Times