HILO, Hawai'i — Kilauea Volcano's vents at Pu'u 'O'o continued their dramatic collapse yesterday while the earth nearby expanded, both clues that an underground flow of magma has probably been diverted and might burst to the surface in a new area, scientists said.

The National Park Service reopened portions of Hawai'i Volcano National Park near the summit of Kilauea Volcano yesterday after the pace of earthquakes, likely caused by the shifting magma, slowed overnight.

The change in the magma flow raised the possibility that lava could break out in an unexpected area, which prompted the closure of most of the park on Sunday.

If lava begins to erupt from a new spot on Kilauea, that would release poisonous fumes and could cut roads and trails or trigger brushfires.

"For that much magma to be intruding or forced into the rift zone, something's got to give as the magma makes room for itself," said Steve Brantley, deputy scientist-in-charge at the U.S. Geological Survey's Hawaiian Volcano Observatory.

Scientists recorded fewer than 10 small earthquakes an hour yesterday, which was far fewer than the 100 earthquakes per hour that were recorded during parts of Sunday.

Among the largest quakes yesterday was a magnitude 3.2 temblor at 2:15 a.m. followed by a magnitude 3.0 quake at 3 p.m.

FLOW TO SEA GONE

While the quakes could indicate magma was flowing into new areas, there "seems to be no lava flowing of any significance on the surface" where it used to stream from Pu'u 'O'o to the sea, said Park Ranger Mardie Lane, quoting observers. "The vigorous steam plume at the ocean entry is now a mere wisp."

Brantley added that it seems clear less lava is flowing into Pu'u 'O'o "because the whole crater floor itself is sort of collapsing inward; it must be due to the lack of support from the magma." The floor of the crater dropped about 20 meters, or about 65 feet.

Meanwhile, the Upper East Rift Zone, an area where the earth is spreading apart, expanded by about 28 inches. Global positioning instruments detected the spreading in the area above Pu'u 'O'o near the hub of Sunday's and yesterday's earthquakes, Brantley said.

A Hawaiian Volcano Observatory field crew also identified new cracking in the area between Mauna Ulu and Makaopuhi consistent with the widening of the rift.

Most of the earthquakes were centered between Pauahi and Makaopuhi craters and were 1 to 2 miles deep.

Parts of the Pu'u 'O'o crater rim to the southwest that have been collapsing during the past several years suddenly dropped an estimated 30 to 50 feet, and the level of lava within the East Pond in the crater has also dropped to "a much lower elevation," Brantley said.

That collapse at Pu'u 'O'o and the apparent stall in the lava flows from the crater area to the ocean strongly suggest the magma flowing into Pu'u 'O'o has been blocked or diverted elsewhere in the East Rift Zone, much as it was during similar events in 1997 and 1999.

ERUPTIONS RESUMED

During the 1997 event, there was no lava visible on the surface of the eruption for 23 days, and in 1999 the flow to Pu'u 'O'o was interrupted for 11 days, but in both cases the eruption at the Pu'u 'O'o crater resumed after the pause.

In the 1997 event, new fissures erupted in and near Napau Crater over a period of 24 hours.

Magma flows into Pu'u 'O'o have been blocked or diverted before, causing pauses of a month or more in the eruption from the Pu'u 'O'o vents, only to have the lava flows resume at the vents later.

The evidence points to an intrusion of magma that began in the Mauna Ulu area early Sunday morning and moved slowly three miles east along the rift zone throughout the day Sunday, and then moved a bit farther east in a burst of earthquake activity that started at about 3:45 p.m. yesterday, USGS scientists said.

MAGMA LEAKS

The deflation of the Kilauea summit continued yesterday, which combined with the ongoing earthquakes suggests magma is still leaking out of the summit magma reservoir into the upper East Rift Zone, Brantley said.

The Hilina Pali Road and the 18-mile Chain of Craters Road visitors use to reach the lowlands where lava flows into the sea will remain closed until further notice, but parks officials decided to reopen Crater Rim Drive around Kilauea caldera yesterday.

"The geologists have informed us that the volcano seems to be quieting, calming, settling somewhat," said Lane, the park ranger. She said parks officials will meet again this morning to decide what steps to take next.

National park crews inspected the Chain of Craters Road for cracks and patched one crack that crossed the entire road near Mauna Ulu, Lane said. The crack was 3 inches wide in places, and crews completed the repairs yesterday, she said.

Despite the closure of portions of the park, Lane said the number of visitors seems to have increased a bit.

"It definitely hasn't put a dent in visitation, and if anything it has probably been a boost in visitation," Lane said. "It's just a really thrilling time to be here."

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.