ESS 106 Lecture 05 June 2013

Usgsgovobservatoriesyvoindexhtml monitoring at

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Unformatted text preview: k Yellowstone calderas 50 miles MOST RECENT ERUPTIONS: -  0.64 m.y. – 1,000 km3 -  1.3 m.y. – 280 km3 -  2.1 m.y. – 2,500 km3 m.y. = million years ago Monitoring at Yellowstone Yellowstone Volcanic Observatory (YVO) Deformation Ground deformation each band represents a swelling/bulge of ground deformation produced by satellites http://volcanoes.usgs.gov/observatories/yvo/index.html Monitoring at Yellowstone Yellowstone Volcanic Observatory (YVO) Deformation Ground deformation Geyser Activity Monitoring at Yellowstone Yellowstone Volcanic Observatory (YVO) Deformation Ground deformation Geyser Activity Earthquakes Seismic imaging of subsuface Monitoring at Yellowstone Yellowstone Volcanic Observatory (YVO) Deformation Ground deformation Geyser Activity Earthquakes Seismic imaging of subsuface Frequency of Activity at Yellowstone The Lowdown: Yellowstone •  It’s not “About to erupt” •  It’s not necessarily “overdue” for an eruption. –  Though the recurrence interval for large eruption is ~600,000 years, and the last one was 640,000 years ago it is a calculated number and doesn't necessarily mean anything other than that •  Biggest potential threat (short term) is phreatic explosions. –  Possibly an effusive rhyolite eruption •  It is being extensively monitored The Climatic Effects of Volcanic Eruptions and Other Gas Hazards Magmatic Gas Content" Typically ~1 – 5 % of the magma MAIN GASES H2O (70-90%) CO2 SO2 TRACE GASES N, H, S, F, Ar, CO, Cl TOXIC GASES HCl, HF H2SO4 H 2S The Climatic Effects of Volcanic Eruptions and Other Gas Hazards GAS HAZARDS -Local, on site hazards -Global climate hazards The hazards of volcanic gas… •  Direct health hazards –  H2S, CO2 –  Dense gases, collect in low areas –  Suffocation •  Indirect effects (SO2, H2SO4, HCl, HF) –  Acid rain –  Destruction of crops (Laki) Lakes Nyos and Monoun, Cameroon •  Volcanic CO2 builds up in lower lake •  Lake overturn releases large amounts of gas –  1984: Monoun (37 fatalities) –  1986: Nyos (~1800 fatalities) •  Extremely rare events Rapid degassing from lakes •  Lake Nyos in Cameroon, 1986 •  Build up of CO2 at base of lake –  When enough present, it overturns –  1 km3 of CO2 was released •  The high density of cold CO2 relative to ambient air allows the gas cloud to flow down topographic depressions and accumulate locally. 1800 people die from asphyxiation. Effects of long-term exposure •  CO2: no adverse effects in low concentrations •  SO2, H2SO4 (sulfuric acid), HCl (hydrochloric acid) –  Dangerous...
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This document was uploaded on 02/24/2014 for the course ESS 106 at University of Washington.

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