A stretch of scenic Diamond Head Road will be closed for about three weeks, starting this morning, so crews can work to prevent more rockfalls.

Recent heavy rain triggered a rockfall last week and the hillside remains unstable above the third lookout, said Peter Young, chairman of the state Department of Land and Natural Resources. State officials will close the road from the second lookout above Ku'ulei Cliffs Beach Park to the intersection with Kahala Avenue to work on the base of Diamond Head, he said.

The road will be open to local traffic but will be closed to everyone else, including buses and pedestrians. Young estimated the work will take about three weeks.

"The loosened material creates hazardous conditions and will be removed from the face of the (Diamond Head State) monument," Young said.

State officials also announced that one lane of Kailua Road heading into Kailua was closed indefinitely last night because of the unstable hillside above it.

The section between St. John's Lutheran Church and Hamakua Drive had been the site of three landslides during recent storms. A state inspector late yesterday afternoon noticed overhanging material, prompting officials to close the right lane.

State Department of Transportation spokesman Scott Ishikawa said another inspection will be made this morning to determine whether the lane could be safely reopened.

"It's been sunny all day, but crews are concerned if we have more rain that it may bring down more material," he said.

Reach Curtis Lum at culum@honoluluadvertiser.com.