Lecture 19 even more volcanoes

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Class Announcements Term Break extra credit option due by end of period today Sign up to attend a Papago Park extra credit field trip (worth 20 points) Options: Wed., April 16: 10-11AM or 4-5 PM Thurs., April 17: 10-11AM or 2-3 PM Today’s Lecture: Chap Volcanoes Class presentations: Cancer-causing gas in Beverly Hills CA - Michael Zara Mt Rainier - Nathan Policar Intermediate volcanoes (cont.) Calderas Volcanic hazards Case Study: Mt Saint Helens Economic aspects: Hydrothermal activity Mineral deposits Volcanic Activity on Other Planets Some Other Important Volcanic Features a Calderas ◆ summit crater greater than km wide ◆ from collapse of summit b Lava domes ◆ viscous felsic magma ◆ usually form after explosive eruption of gas-rich magma Fig 09.11ab W W Norton Volcano starts to erupt Ash and debris Full magma chamber Main explosive eruption Magma chamber empties Newly formed caldera Collapsed blocks Empty magma chamber New volcanic cone grows Lake fills caldera Fig 09.29b © 1997 Birke Schreiber Case study: Mt St Helens 9500’ ● Ejected nearly a cubic kilometer of ash & rock debris ● 59 deaths 8150’ ● Ash blown over 11 miles high! (1350’ shorter!) Fig 09.15 W W Norton Fig 09.16abc W W Norton Fig 09.22e Photo by J Marso, U.S Geological Survey Volcanic mudflows Mount Saint Helens A lava dome formed in crater after major eruption GENERA L FEA TURES OF HY DROTHERMA L SY STEMS  Hydrothermal Systems:  Develop anywhere that fluids coexist with a heat source  Typical heat source a magma intrusion  Effects: Alteration of adjacent rocks and deposition of mineral deposits, often of economic importance  Also a source of geothermal energy Grand Prismatic Spring Videos: Types of Volcanic Eruptions 1: Lava flows 2: Ash falls 3: Ash flows 4: Mud flows VENUS Volcanoes Elsewhere in Solar System MARS Fig 09.30a JPL / NASA Olympus Mons: Largest Volcano in the Solar System Olympus Mons, Mars Jupiter’s moon “Io” From Scientific American, Feb 2000 ● Jupiter’s moon “Io” Volcanic Eruptions in Progress on Io Fig 09.30b JPL / NASA [...]...Mount St Helen’s Lava dome Case study: Mt St Helens Case study: Mt St Helens •Located in the Cascade volcanic range, NW US •Result of past/present subduction of oceanic crust in the Cascadia Trench •Many volcanoes there are still active Case study: Mt St Helens 9500’ ● Ejected nearly a cubic kilometer of ash & rock debris ● 59 deaths 8150’ ● Ash blown over 11 miles high! (1350’ shorter!) Fig 09.15 W W... mineral deposits, often of economic importance  Also a source of geothermal energy Grand Prismatic Spring Videos: Types of Volcanic Eruptions 1: Lava flows 2: Ash falls 3: Ash flows 4: Mud flows VENUS Volcanoes Elsewhere in Solar System MARS Fig 09.30a JPL / NASA Olympus Mons: Largest Volcano in the Solar System Olympus Mons, Mars Jupiter’s moon “Io” From Scientific American, Feb 2000 ● Jupiter’s moon
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