1. lava tube
Wikipedia definition
2. Lava tubeLava tubes are natural conduits through which lava travels beneath the surface of a lava flow, expelled by a volcano during an eruption. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channel. Lava tubes have been reported on the Moon.
Read “Lava tube” on English Wikipedia
Read “溶岩洞” on Japanese Wikipedia
Read “Lava tube” on DBpedia


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