Such eruptions occur when the conduit connecting the summit to the magma chamber below is blocked, forcing the magma to move laterally.
At some volcanoes, flank eruptions are common, and occur along clearly defined rift zones.
This is the case at Mauna Loa and Kilauea volcanoes in Hawaii, Piton de la Fournaise on Reunion Island,[1] and Mount Etna in Italy.
[2] Flank and summit eruptions may occur at the same time.
Collapse-drive eruptions are among the largest and most destructive volcanic phenomena.