Volcanoes and volcanology | Geology Kilauea; Mount Etna; Mount Yasur; Mount Nyiragongo and Nyamuragira; Piton de la Fournaise; Erta Ale Volcanoes and volcanology | Geology Kilauea; Mount Etna; Mount Yasur; Mount Nyiragongo and Nyamuragira; Piton de la Fournaise; Erta Ale