Kilauea's lavas yesterday were flowing slowly across 20-year-old lavas and through 'ohi'a forest high on the volcano's east rift zone.

"It looks like a coherent flow, but there are a lot of lobes," said Jim Kauahikaua, scientist in charge at the Hawaiian Volcano Observatory.

Most of the new lava is material that is oozing out of the molten core of the main flow in the area to the northeast of the Kupaianaha crater, he said.

Scientists are referring to four active cracks that opened up July 21 between the Pu'u 'O'o cone and the older Kupaianaha vent as Fissures A through D, with D closest to Kupaianaha. A panoramic view of the fissure area is available on the observatory Web site at www.hvo.wr.usgs.gov/cam3/.

Yesterday, only C and D were active, Kauahikaua said, with C occasionally burping up gobs of lava that generally stayed at the fissure. Fissure D, by contrast, fed a lava flow that has been heading around the northern side of Kupaiahana.

"It's mostly 'a'a lava, but some of it looks like it's trying to be pahoehoe," Kauahikaua said. 'A'a is rough, chunky lava, while pahoehoe is more fluid-looking with a surface that is often described as ropey.

Kauahikaua said that volcano scientists believe the vents are being fed by an underground flow of magma that runs through the magma chamber under the Pu'u 'O'o cone and then continues on out the northeast rift zone to the fissures. Scientists have been unable to make accurate calculations of how much lava is being produced, since they can't get a clear assessment of how big the channel is that runs from Fissure D to the end of the flow northeast of Kupaianaha.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.