1. Volcanoes as Possible Indicators of Tectonic Stress Orientation – Principal and Proposal D. Dziekan

2. Purpose Concerned with radial dikes –Indicated by flank crater distribution Use distribution for average tectonic stress orientation

3. 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

4. Repeated eruptions –All from same vent or vents –Form large volcanic edifices Form pipe shaped conduit for magma Polygenetic Volcanoes

5. Flank Volcanoes Manifestation of underground dikes Possible to depict regional stress Conduits most likely fissure shaped –Most are monogenetic volcanoes

6. Tectonic Setting Data collected from several sources –Japan –Andes –Aleutians –Central America

7. Tectonic Setting Extensional setting –Maximum compressional stress vertical –Parallel

8. Tectonic Setting Contractional Setting –Maximum compressional stress horizontal –Typically high angle

9. 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

10. 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