GEOL 1003 Study Guide - Midterm Guide: Plinian Eruption, Mid-Ocean Ridge, Mercalli Intensity Scale

• School: University of Oklahoma
• Department: GEOL
• Course: GEOL 1003
• Professor: Barry Weaver

Document Summary

Long-lived, active from 100,000 to 1,000,000 yrs. Height to 4-5km, slope 15 to 33 degrees. Made from andesite lava flows and pyroclastic deposits; composite. Height a few 100m, slope 30 to 33 degrees. Parasitic on shield volcanoes, numerous cones in large volcanic fields. Ex, numerous cones in western s (capulin, sunset crater) Essentially a crater due to land collapse. Forms as a result of rapid, large volume eruption from a shallow magma chamber. As the magma chamber empties, the roof collapses catastrophically to leave a steep walled, flat floor depression. Can develop at the summit of a volcano. Volcanoes can erupt passively (lava flows and domes) or explosively (pyroclastic deposits) Lava flow (aa, pahoehoe); scoria cone from lava fountaining. Cinders and bombs build a scoria cone. Moderately violent explosive gas blast; eruption column. Sustained vertical gas blast; high eruption column. Air-fall deposits; pyroclastic flows/surges from eruption column collapse. The 79 ad eruption of esuvius, italy.