Magma pumping into Kilauea volcano's upper East Rift Zone has buried under lava or scorched nearly seven acres of rainforest, with heat and gases wilting and sickening trees, ferns and other plants around two large cracks that opened this week as the rift expanded.

Scientists yesterday also saw steam escaping from a third large crack that opened as magma was injected under the area. The magma flowing in from below has caused the East Rift to expand by about 39 inches.

High levels of sulfur dioxide gas leaking from Kilauea's summit caldera prompted National Park Service officials to keep four miles of Crater Rim Drive closed, from Jaggar Museum to the Chain of Craters Road junction. The East Rift and coastal zones of Hawai'i Volcanoes National Park also remained closed.

The pace of the earthquakes that signaled the start of the latest changes at the volcano early Sunday continued to slow yesterday, but there was still activity underground.

In the Kane Nui o Hamo area of the upper East Rift Zone "there's been a lot of tremor, so the ground's been shaking quite a bit, which could mean more magma moving around," said David Wilson, seismic network manager for the U.S. Geological Survey's Hawaiian Volcano Observatory.

Magma that forced its way into the upper East Rift Zone of Kilauea has caused hundreds of earthquakes, and reached the surface late Monday or early Tuesday at Kane Nui o Hamo to create a new area of eruption before stalling.

The earthquakes seemed to block or divert the flow of magma into the Pu'u 'O'o area and from there down to the sea, which in recent years has been the focus of the Kilauea eruption. Scientists say they aren't sure what to expect next from this eruption, which began in 1983.

If the lava flow resumes at Kane Nui o Hamo, it could threaten more of the rainforest, including the 2,500-acre East Rift Rainforest Special Ecological Area, a forest protected from invasive, non-native plants and animals.

Jim Gail, chief of interpretation for Hawai'i Volcanoes National Park, said park officials plan to set up a "frog pond" in a parking lot today to supply water for helicopter drops if a new lava flow starts a fire in the pristine forest.

About a dozen rare plants are growing in the area, and despite the ecological value of the upper East Rift area, park officials had no choice but to stand by yesterday as parts of the forest were damaged by sulfuric gases from the new cracks in the upper East Rift zone.

"It's just dying in place because of the acidity," Gail said. "It's just being scorched by the acids."

The national park's eastern boundary in the Puna district near Kalapana remains closed, along with Chain of Craters Road and Hilina Pali Road.

However, much of the park remains open, including most of Crater Rim Drive, the Kilauea Visitor Center, Jaggar Museum, Thurston Lava Tube, Volcano House Hotel, Kilauea Military Camp, and Volcano Art Center Gallery.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.