The state Department of Land and Natural Resources yesterday closed the Kahauale'a Natural Area Reserve to public access, citing severe hazards associated with the three new erupting volcanic vents on Kilauea's East Rift Zone.

Hawaiian Volcano Observatory geologists said the region near the vents is extremely unstable, with new rockfalls, collapses, cracks and floods of lava that can't be anticipated.

Lisa Hadway, an ecologist with the state's Natural Area Reserves System program on the Big Island, said specific threats include numerous large cracks in the ground that have formed and are continuing to form in the area, the threat of wildfire from the lava flows, toxic fumes from the eruption, and the likelihood that lava contained in ponds above ground level will spill suddenly, overcoming anyone who may be near. In addition, areas around the Pu'u 'O'o vent, the previous eruption site, are collapsing, she said.

The entire current eruption is within the Kahauale'a Natural Area Reserve, which lies generally northeast of the Hawai'i Volcanoes National Park boundary. The best-known trail in the area, variously known as the Captain's Trail, Kahauale'a Trail and Pu'u 'O'o Trail, was closed by the state yesterday. State conservation enforcement officers will patrol the area regularly, the DLNR said in a press release.

The Kahauale'a Natural Area Reserve is the second-largest in the state system. It runs from 3,900 feet above sea level to 1,400 feet above sea level, and most of its vegetation is considered lowland wet forest, Hadway said. The dominant tall tree is 'ohi'a, with a dense understory of uluhe fern, smaller trees such as kopiko and kolea, tree ferns and understory plants. The state's largest population of the endangered fern Adenophorus periens is found here.

Hadway said the reserve is important habitat for some of the more common Native Hawaiian forest birds, including the 'apapane, 'amakihi, 'elepaio and the 'io or Hawaiian hawk.

The eruption is not doing serious damage to the forest, largely because current flows are running out over lava that flowed in the area from 1986 to 1992.

"At this point, it's flowing over flows of 15 years ago that do not have much vegetative cover," Hadway said.

Hawaiian Volcano Observatory chief Jim Kauahikaua said the eruption is creating a series of what geologists are calling "perched ponds" of lava. In essence, the edges of pools of lava harden into rock and create walls that allow the lava pond surface to be much higher—in some cases as much as 15 feet higher — than the surrounding land, like a volcanic above-ground swimming pool.

The walls of these perched ponds are not particularly stable, and geologists say they have breached repeatedly, allowing large volumes of lava to flood onto the surrounding terrain. At least one of those perched ponds breached Sunday and two more breaches in other ponds were spotted Tuesday.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.