* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Note - ees.nmt.edu
Survey
Document related concepts
Axial Seamount wikipedia , lookup
Mount Garibaldi wikipedia , lookup
Shield volcano wikipedia , lookup
Llullaillaco wikipedia , lookup
Mount Pleasant Caldera wikipedia , lookup
David A. Johnston wikipedia , lookup
Types of volcanic eruptions wikipedia , lookup
Mount Meager massif wikipedia , lookup
Mount Edziza volcanic complex wikipedia , lookup
Volcanology of Mars wikipedia , lookup
Cascade Volcanoes wikipedia , lookup
Mount Pinatubo wikipedia , lookup
Volcanology of Io wikipedia , lookup
Silverthrone Caldera wikipedia , lookup
Mount St. Helens wikipedia , lookup
Cerro Azul (Chile volcano) wikipedia , lookup
Nevado del Ruiz wikipedia , lookup
Transcript
Other volcanic features • Flood basalts – Largest volcanic events in terms of volume – Volatiles, viscosity are low, so not very explosive – Cover large areas w/ thick layers of lava • Lava domes – Hardened dome/plug of magma cools quickly – Can form in hours, continue for years, decades Flood Basalts Lava Domes Lava Dome, Mt. St. Helens Volcanic Hazards Outline • Types of volcanic hazards Volcano Classification • Active: currently erupting or has erupted in historical time • Dormant: presently inactive but may erupt again (examples: Cascades) • Extinct: not active, not expected to be active for long time in future Cumulative Deaths Due to Volcanic Hazards in past 2000 years Causes of Deaths How bad can it be? • • • • • • • • • • 1815 1822 1826 1883 1902 1902 1919 1951 1982 1985 Indonesia Indonesia Indonesia Indonesia Martinique Guatemala Indonesia New Guinea Mexico Columbia 92,000 died* 5,500 killed 3,000 killed 36,417 killed 29,025 killed 6,000 killed 5,110 killed 2,942 killed 1,700 killed 23,000 killed Pyroclastic Flow • Most deadly of all hazards • Superhot, fast moving cloud of volcanic gas, steam, debris • 200-700 degrees C, 80 km/hr (hurricane speeds!) Generation of pyroclastic flow • Eruption column collapse • Dome collapse • Directed blasts Pyroclastic flows QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Mayon, Philippines, 1984 Effects of Pyroclastic Flows • Destroys nearly everything in path – – – – Structures Burial of sites Burn forests, crops, structures Melt snow to form lahars Building destruction QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Remnant of building after eruption of El Chichon, Mexico in 1982 Note reinforcement rods bent in direction of flow Effects of pyroclastic flows QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Mt. St. Helens - forest destruction Effects on people • • • • Physical impact Burns Inhaling superhot gases Usually quick death Examples • Many examples of devastating pyroclastic flows – Unzen, Japan – Chichon, Mexico – Mt. Pelee, Caribbean* Mt. Pelee • 1902-1903, 1929-1932 significant pyroclastic flows • Many from directed blasts, deadliest in 1902 – Viscous magma filled crater – May 1902, several pyroclastic flows, traveling ~190 km/hr – Destroyed St. Pierre (~30,000 people) and other towns in area Mt. Pelee Large area affected by 1902 pyroclastic flows Eruption Debris • Includes cloud, bombs, ash fall • Bombs kill small # of people every year • Clouds – Planes fly into cloud - dangerous • Over 25 years, ~60 jets damaged • Ash fall – Bury cities Ash fall hazards Roof collapse QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Mid-Afternoon daylight gone QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Water systems can clog Kamchatka eruption, seen by space shuttle Cloud Hazard QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Ash from Mt. Spurr traveled around for days (satellite image) Example - Mt. Vesuvius 79 AD • Cause of volcano: subduction • Region near Pompeii also had earthquakes, but city of ~20,000 people not deterred to move • Significant volume of material erupted (4 km3) in first wave – Pompeii buried by ash/pumice 3 m deep • Later pyroclastic flows continued to bury city Vesuvius QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Remains of Pompeii after 79 AD eruption Tsunami • Wave caused by undersea vertical displacement (like earthquakes) • Volcanic eruption can also cause tsunami – Pyroclastic flow or lava dome avalanche – Collapse of cone or crater Example - Krakatau 1883 • • • • • Stratovolcano between Java and Sumatra Subduction zone Collapse led to tsunami ~35 m (115 ft) Death toll ~36,000 New cone appeared in 1927 Collapse of Krakatau QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncomp resse d) de com press or are nee ded to s ee this picture. QuickTime™ and a TIFF (Uncomp resse d) de com press or are nee ded to s ee this picture. Anak Krakatau Lahars • Mudflow of volcanic debris, produced when pyroclastic debris or lava mix with rain, snow, ice, lakes • Can travel quickly (40 mph) and significant distances (10s of miles) Dark pathways - lahars triggered by Mt. St. Helens eruption, 1985 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. “Cloud” upriver: lahar traveling down riverbed in Guatemala Home destroyed from lahar - Mt. Unzen, Japan lava dome collapse and later rains, 1993 Example - Nevado del Ruiz 1985 • Colombian volcano, small glacier on top • Small eruption caused melting, sending mud down the mountain • Covered most of town of Armero with ~26 ft thick mud – Killed ~22,000 Nevado del Ruiz, 1985 River valley with lahar remains QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Town of Armero Famine • Indirect hazard • Eruptions change climate – Can harm plants, animals Iceland eruption, 1783 • Fissure eruption of basalt • Released gas rich in SiO2 and fluorine – Slowed grass growth and added significant amounts of fluorine to grass – Killed significant population of livestock • ~20% of Iceland population died due to famine Tambora, 1815 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. • Indonesian volcano, most violent eruption in last 200 years • Significant Plinian eruption • Next pyroclastic flows (12mi3 of material) • Deaths in region ~90,000 (10% during eruption, 90% later) • 1816 - year without summer – Affected global climate Gas • Gas can escape from basaltic magmas – CO2 gas is common • Depending on gas, can kill plants in region • Can also be trapped in water Example - Lake Nyos, Cameroon • Area of failed rifts with some remaining volcanic activity • 1986 - gas burp from the lake – Sent rivers of gas down into valleys ~25 km (16 mi) • Effects - ~1700 deaths, no animals alive – Plants ok though Why? • CO2 gas leaking out of basaltic magma • Dissolved in bottom waters of lake (held down by pressure) • Some event caused overturn – Eruption, earthquake, landslide, temp change all possible triggers • Gas release “river” ~50 m thick Lake Nyos QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Efforts to pump water, gas out of lake Lake Nyos QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Continued hazard? • • • • YES! Still some gas remaining Continues to build up Possible ways to pump gas out to reduce risk Lava Flows • Not big hazards in terms of fatalities • Moves too slow to kill people • Can destroy towns, villages Kilauea, HI • Few lives lost • Mostly structural losses QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 1973 Flows in Iceland • Lava flows threatened town, harbor • Built diverters to control flow • Sprayed water to harden flows, move to flow in other direction away from harbor QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Man vs. volcano! Actually gained land and improved harbor Next Time • U.S. volcanoes and related hazards