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Volcanoes as Possible Indicators of Tectonic Stress Orientation – Principal and Proposal. D. Dziekan. Purpose. Concerned with radial dikes Indicated by flank crater distribution Use distribution for average tectonic stress orientation. Monogenetic Volcanoes. One eruption
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Volcanoes as Possible Indicators of Tectonic Stress Orientation – Principal and Proposal D. Dziekan
Purpose • Concerned with radial dikes • Indicated by flank crater distribution • Use distribution for average tectonic stress orientation
Monogenetic Volcanoes • One eruption • From vent or fissure, essentially dikes • Produces maars, scoria cones, lava domes, or shield volcanoes • Underground conduit formed anew with each eruption • Fissure shaped conduit, not pipe shaped
Polygenetic Volcanoes • Repeated eruptions • All from same vent or vents • Form large volcanic edifices • Form pipe shaped conduit for magma
Flank Volcanoes • Manifestation of underground dikes • Possible to depict regional stress • Conduits most likely fissure shaped • Most are monogenetic volcanoes
Tectonic Setting • Data collected from several sources • Japan • Andes • Aleutians • Central America
Tectonic Setting • Extensional setting • Maximum compressional stress vertical • Parallel
Tectonic Setting • Contractional Setting • Maximum compressional stress horizontal • Typically high angle
Trend of Radial Dikes • Other possible means to reveal trend • Bending of radial fissures • Elongation of main volcanic edifices • Many parallel normal faults within edifices
Conclusion • Focused on principals • Introduced knowledge to be used in the future • Article contained a lot of ‘could’ and ‘possibly’ • Use flank craters to determine dike trends • Dike trends suggest stress orientation