Federal emergency officials toured tornado-ravaged areas in Northern Virginia yesterday, the neighborhoods' first step toward obtaining federal relief funds.

Walking gingerly around downed oak trees and peering into tarp-covered kitchens, Federal Emergency Management Agency workers visited a dozen or so of the most heavily damaged homes in Prince William County, focusing on whether they can be safely occupied. The team filled out checklists, took photographs of damage and defined locations using GPS plotters, said Ed Patterson, a FEMA worker who traveled from the agency's Texas office to assess Virginia's damage. The team did the same thing in Fauquier County yesterday.

The assessment will be used by Gov. Mark R. Warner (D) in deciding whether to ask for federal disaster funds to help property owners repair their homes. Warner's statewide declaration of a state of a emergency was unrelated to any official request for federal money.

Tropical Depression Ivan spawned more than 50 tornadoes across the state, including 17 that touched down, bringing winds of up to 206 mph. The storm and tornadoes destroyed a dozen homes, damaged 547 others and caused widespread crop damage, authorities said. Eleven injuries and one death -- in Campbell County -- were attributed to the storm, according to the Virginia Department of Emergency Management.

There is no set threshold of damage to qualify for federal disaster relief, and the scattered impact of Ivan on Virginia might hurt the state's chances for federal aid, officials said.

"A heavy concentration of damage generally indicates a greater need for federal assistance than widespread and scattered damage throughout a state,'' said Barbara J. Ellis, FEMA spokeswoman.

FEMA also takes into consideration the capacity of local relief organizations and whether an affected area is insured for damage such as flooding. Federal assistance usually provides direct aid to homeowners who need money for repairs.

Virginia officials said they did not know when the assessment of damage in the state would be complete. In Fairfax County, where 51 homes were damaged and one was destroyed, officials said yesterday that FEMA had not contacted the county about an inspection.

If no federal assistance is received, Virginia homeowners would be able to apply to charities for help, said Dawn W. Eischen, spokeswoman for the state Department of Emergency Management. Small businesses may be able to apply for low-cost loans and other government services open to them.

The remnants of Ivan shook apples off trees in Virginia's Frederick County, 60 miles west of Washington, just as the harvest was beginning. Pumpkins and cabbages were lost in the eastern part of the state -- in addition to the rampant disease caused by heavy rains.

The random, almost pinpoint devastation of Friday's storm was evident in the Prince William neighborhoods that FEMA representatives toured yesterday. One side of the street would be picture perfect, while the other side looked as if it were the site of an impromptu logging operation.

Staff writer David Cho contributed to this report.

Bill Lloyd of the Virginia Department of Emergency Management takes notes at a home in Prince William County.