(Reuters) - A blaze that has scorched some 43,000 acres (17,400 hectares) and destroyed dozens of homes near California's famed Big Sur coast was sparked by an illegal, unattended camp fire in a state park, authorities said on Tuesday.

The so-called Soberanes Fire, which erupted on July 22, began as a small blaze, 2 feet (60 cm) in diameter, ignited by unknown individuals in a section of Garrapata State Park that was closed to camping and campfires, according to U.S. Forest Service spokesman Don Jaques. No arrests have been made, he added.

The more than 5,450 fire personnel battling the blaze have been able to draw containment lines - a measure of how much of its perimeter has been cleared by fire crews of unburned vegetation - around only 18 percent of the wildfire so far.

Steep, mountainous terrain as well as hot, dry conditions have hampered efforts to quell the fire tearing through drought-parched chaparral, grass and timber.

One person, a bulldozer operator hired by property owners to help battle the flames, died last week when his vehicle rolled over. It was the second California wildfire-related death in a week.

In addition, 57 homes and 11 other structures have been destroyed while some 2,000 remained under threat on Tuesday, fire officials said. About 350 residents have been ordered to evacuate the area, though some evacuation orders have since been lifted.

The fire threat, coming in the middle of the region's summer travel season, has prompted the closure of several popular California campgrounds and recreation areas along the northern end of the Big Sur coastline, including Point Lobos State Natural Reserve and Pfeiffer Big Sur State Park.

Another fire broke out on Saturday in grass and brush about 30 miles (48 km) northeast of Fresno, in central California. It has since charred about 2,020 acres (817 hectares) and is threatening 400 structures, prompting evacuations in the area, according to the California Department of Forestry and Fire Protection.

Five structures, including three homes, have been destroyed, fire officials said. On Tuesday morning, the so-called Goose Fire was listed as 30 percent contained.

(Reporting by Steve Gorman in Los Angeles and Curtis Skinner in San Francisco; Editing by Jonathan Oatis and Tom Brown)