After a quiet week on Kilauea Volcano, officials with the Hawai'i Volcanoes National Park will reopen all major roads in the park at mid-morning today, including the 18-mile Chain of Craters Road.

Park Superintendent Cindy Orlando said in a written statement yesterday that eruptive activity is approaching an "all-time low relative to the last 25 years."

"Based on communications with scientists at the Hawaiian Volcano Observatory, we feel confident that roads and coastal trails can be safely reopened," she said.

Chain of Craters Road was closed June 17 after a swarm of earthquakes signaled a magma intrusion into the upper East Rift Zone, causing the rift to expand and open several large cracks. Two days later lava briefly flowed from a 275-yard fissure in a remote part of the rift zone near Kane nui o Hamo, but the flow ended within hours.

Since then, seismic activity and the tremor associated with underground magma movement have decreased, and the Pu'u 'O'o eruption that had been pouring lava into the sea was choked off.

"Kilauea is perhaps the world's most active volcano," said Orlando. "We appreciate the momentary calm, but know better than to be lulled into complacency."

Kilauea's East Rift remains closed, including Napau Trail and Campsite, and Naulu Trail. The park's eastern boundary near Kalapana is also closed, as is Pu'u 'O'o itself. The cinder and spatter cone are extremely unstable, and are continuing to collapse.

The parking lot at Mauna Ulu also is closed as firefighters carry out fire suppression activities including helicopter operations. Firefighters have set up five "frog ponds" that can hold up to 15,500 gallons of water at the Mauna Ulu parking lot to be used for helicopter water drops.

Firefighters this week used a helicopter rigged to haul a 100-gallon bucket to dump water on smoldering brush ignited by the short-lived lava outbreak at the upper East Rift Zone.

The water drops were an effort to protect animals and rare native plants in the park's 2,700-acre East Rift Special Ecological Area.

About seven acres have burned or been scorched by the lava and fires started by the short-lived flow, and vegetation on another 20 acres has wilted or died off because of fumes and volcanic gases released from new cracks that broke open in the East Rift last week.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.