WASHINGTON (TIP): The first human settlers on the moon may live inside giant lava tubes large enough to house cities, which were formed by ancient volcanic eruptions, new research suggests.

The volcanic features are an important target for future human space exploration because they could provide shelter from cosmic radiation, meteorite impacts and temperature extremes, researchers said.

Lava tubes are tunnels formed from the lava flow of volcanic eruptions. The edges of the lava cool as it flows to form a pipe-like crust around the flowing river of lava. When the eruption ends and the lava flow stops, the pipe drains leave behind a hollow tunnel, said Jay Melosh, a Purdue University distinguished professor of earth, atmospheric and planetary sciences who is involved in the research.

“There has been some discussion of whether lava tubes might exist on the moon,” he said. “Some evidence, like the sinuous rilles observed on the surface, suggest that if lunar lava tubes exist they might be really big,” said Melosh.

Sinuous rilles are large channels visible on the lunar surface thought to be formed by lava flows. The rilles range in size up to 10kms wide, and the team explored whether lava tubes of the same scale could exist.