Caldera collapse: Perspectives from comparing Galápagos volcanoes, nuclear-test sinks, sandbox models, and volcanoes on Mars

[摘要] The 1968 trapdoor collapse (1.5 km3) ofFernandina caldera in the Galapágos Islands developed the same kinds of structuresas found in small sandbox-collapse models and in concentrically zoned sinks formedin desert alluvium by fault subsidence into underground nuclear-explosion cavities.Fernandina?s collapse developed through shear failure in which the roof above theevacuating chamber was lowered mostly intact. This coherent subsidence contraststo chaotic piecemeal collapse at small, rocky pit craters, underscoring the roleof rock strength relative to subsidence size. The zoning at Fernandina implies thatthe deflated magma chamber underlay a central basin and a bordering inward-dippingmonocline, which separates a blind inner reverse fault from an outer zone of normalfaulting. Similar concentric zoning patterns can be recognized in coherent subsidencestructures ranging over 16 orders of magnitude in size, from sandbox experimentsto the giant Olympus Mons caldera on Mars.

[学科分类] 地质学

[关键词] Fire safety;fatal fires;smoke alarms