Honolulu: Scientists in Hawaii have captured rare images of blue flames burning from cracks in the pavement as the Kilauea volcano gushes fountains of lava in the background, offering insight into a new dimension in the volcano's weeks-long eruption.

Volcanos produce methane when hot lava buries and burns plants and trees. The gas flows through the ground and up through existing cracks.

"It's very dramatic. It's very eerie," Jim Kauahikaua, a US Geological Survey scientist, told reporters.

He said it was only the second time he's ever seen blue flames during an eruption.

The methane can seep through cracks several metres away from the lava. It can also cause explosions when it's ignited while trapped underground. These blasts can toss blocks several feet away, said Wendy Stovall, also a scientist at the Geological Survey.