A small pond of water has been discovered inside the summit crater of Hawaii's Kilauea volcano for the first time in recorded history, possibly signaling a shift to a more explosive phase of future eruptions.

The U.S. Geological Survey says that after a week of questions about a green patch inside Kilauea's Halemaumau crater, researchers were able to confirm the presence of water on Thursday.

USGS scientist Don Swanson says the pond has grown in size over the past week.

Swanson says the bottom of the crater, which once housed Kilauea's famed lava lake, is now below the water table and researchers believe the pond is coming from that groundwater.

Lava interacting with the water table can cause explosive eruptions.