The park will be closed on the afternoons of four non-consecutive days: Jan. 17, Jan. 19, Jan. 22 and Jan. 24. On those days, the park and trail will open to park users at 6 a.m. and close at 1 p.m.

During the remainder of assessment days, the park will maintain regular operations hours, 6 a.m. to 6 p.m., and visitors will be allowed to hike to the summit.

The assessment will involve inspection of both the summit trail and the vertical rock faces above and below portions of the trail, according to the state Department of Land and Natural Resources.

"Diamond Head State Monument is one of our most popular state parks, with over 600,000 visitors a year, and an average of 1,800 visitors per day to the historic summit trail," DLNR Chairman Peter Young said in a news release. "Given the heavy use of the summit trail, it is important to maintain trail safety for park visitors."

He added, "This summit trail inspection is the latest in recent park improvement measures made over the past few years at Diamond Head State Monument, including improvements to the summit lookout, and lighting the tunnel and the spiral staircase along the upper portion of the summit trail."

Earth Tech Inc., an environmental geotechnical firm, will assess rockfall hazards in and around Diamond Head State Monument, including the historic summit trail inside the crater. Other sites at Diamond Head State Monument that will be assessed include the exterior face of the Kahala Tunnel entrance into the crater, the road cuts for Diamond Head Road and Poka Place.

Dan Quinn, state parks administrator, said, "During the summit trail assessment, partial closure of this heavily visited park is necessary, as consultants will be using equipment in narrow portions of the trail where no bypass is available, and rocks may be dislodged in the process."

Once the rockfall assessment is complete for each location, Earth Tech will make recommendations that identify viable options for optimum safety and design the most feasible hazard mitigation methods at each location. Earth Tech will also do the design and permitting, and provide inspection during the work.

Diamond Head State Monument was named a national natural landmark in 1968 because it is an excellent example of a pyroclastic volcano with a typical erosional pattern that has created the crater profile. Most visitors hike the historic 0.8 mile summit trail, built about 100 years ago, for a view from the highest point of the crater rim.