Story highlights Lava from a vent has come within a mile of the edge of the Ka'ohe Homesteads subdivision

Hawaii County Mayor Billy Kenoi declares an emergency, asks Gov. Neil Abercrombie for help

U.S. Geological Survey says the lava could reach a subdivision boundary in less than a week

No evacuations have been ordered, but access to roadways to the community is restricted

The Hawaiian Volcano Observatory has issued a warning for a Big Island beach community threatened to be cut off by lava flow from Kilauea Volcano.

Lava from a vent that opened on June 27 has come within a mile of the edge of the Ka'ohe Homesteads subdivision in the District of Puna, northeast of the volcano, Hawaii County Mayor Billy Kenoi said.

Kenoi signed an emergency proclamation Thursday and asked Hawaii Gov. Neil Abercrombie for emergency assistance.

"We are taking this step to ensure our residents have time to prepare their families, their pets, and their livestock for a safe and orderly evacuation from Ka'ohe in the event the flow continues to advance," Kenoi said in a news release.

Highway 130 separates the district of Puna from the rest of the county. The U.S. Geological Survey predicted the lava could cross the highway in the next week.

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"We project that lava could reach the Kaohe Homesteads boundary within 5 to 7 days," the USGS said Thursday . Since July 10, the lava has advanced at an average rate of 820 feet per day, but as fast as 1,600 feet per day, the agency said.

"When this occurs, communities south of the crossing will be isolated from the rest of the county," Kenoi said.

Evacuations had not been ordered as of Friday morning, but Hawaii County's civil defense restricted access to roads to the Ka'ohe community, civil defense administrator Darryl Oliveira said.

"Only residents will be allowed on the subdivision roads starting today, and we ask that nonresidents stay away from the area," Oliveira said. "The lava cannot be seen from the subdivision, and there is no reason for nonresidents to be in the Ka'ohe subdivision at this time."

More than 8,211 people live in the threatened area, according to a 2010 census.

Kilauea Volcano has been active since 1983, with 61 USGS-recorded eruptions. "Kilauea ranks among the world's most active volcanoes and may even top the list," the agency said.

In 1983, lava from Kilauea destroyed 16 homes in the Royal Gardens subdivision, a community built on a slope downhill from the volcano. Today, only 35% of the abandoned development can be seen. Lava overran the rest of the community.