3/7/17. #17 - Volcanoes: Benefits and Hazards. Announcements

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1 Announcements #17 - Volcanoes: Benefits and Hazards Exam #1 results + key will be posted within a few days Conflict exams: Arranged with Fangruo Web Ex #3 starts later today, due in one week Check your grades Eyjafjallajökull volcano, Iceland, 2010 Volcano Benefits - Erupted Rock Pumice - highly porous volcanic rock Used in skin care, Lava soap, dental polish, pencil eraser Volcano Benefits - Erupted Rock Obsidian - glassy volcanic rock Used as decorative stone, weapon, surgical tool (better than steel!) Volcano Benefits - Erupted Rock Cinders - gravel-size pyroclastic debris/glass, used in road construction, track surfaces, mulch Volcano Benefits - Geothermal Energy heat from shallow magma used to generate electricity; need circulating groundwater to transfer heat to surface as hot water and steam, which drive turbines Volcanic ash - sand-size volcanic glass, can be fertile soil World's largest geothermal plant The Geysers, central California 1

2 Volcano Benefits - Tourism National parks and monuments Volcano Benefits - Ore Deposits Many metallic ore deposits in roots of old volcanoes Volcanogenic Massive Sulfide Deposit Kidd Creek Ore (Cu-Zn-Pb-Ag-Sn) Deposit Volcano Hazards - Lava Flows Usually non-lethal, can cause considerable damage. Unlike other hazards, which generally decrease severity away from origin, lava flow burns or buries everything in its path until it stops Volcano Hazards - Lava Flows (Kilauea) 1984 November 11, 2014 Lava Flows from Kilauea, Hawaii November 14, 2014 Lava Flows from Paricutin volcano, Mexico Video of volcanologist descending into crater with bubbling lava (Marum Volcano on Ambrym Island in southwest Pacific, YouTube, 1 min. Explosive eruption of plume of volcanic ash (small, abrasive pieces of rock) can cause crop damage, livestock deaths Roof collapse from heavy ashfall - Mt. Pinatubo, 1991 Ashfall from Mt. St. Helens, 1980 Knocking ash from crops (Mt. Merapi, Indonesia) House destroyed by ashfall, Rabaul Caldera, Papua New Guinea Ash from Etna volcano Italy 2

3 Eyjafjallajökull eruption, Iceland, 2010 Pronuciation: tch?v=hso_nd41-6g Redoubt Volcano, Alaska, 1989 Air routes pass over or near >100 active volcanoes Airplane engine failure Volcano Hazards - Ashflow/Pyroclastic flow Explosive eruption of huge amount of magma, creates turbulent mixture of superheated gas + pyroclastic debris (nuee ardente = "glowing cloud") that flows down mountain-side with great speed (up to 150 km/hr); temperatures can exceed 600 C Volcano Hazards - Ashflow/Pyroclastic flow Ashflows can cause huge destruction, common during caldera-forming eruptions Ashflow damage from Mt. Merapi, Indonesia in 2010 Mayon Volcano, Philippines, in 1984 Ashflow damage from Soufrière Hills, Montserrat in 2005 Ashflow Case History: Mt. Pelée Mt. Pelée eruption in 1902 on Caribbean island of Martinique destroyed city of St. Pierre, killing ~28,000 in ~30 seconds St. Pierre before and after 1902 ashflow eruption of Mt. Pelée (in background) Volcano Hazards - Ashflow/Pyroclastic flow Personal video - pyroclastic flow at Unzen Volcano, 1991 (4:09-4:50) Volcano video (National Geographic, 1:12, pyroclastic flow at Unzen Volcano, 1991, Soufriere Hills Volcano, Montserrat, in 2010 Mt. Pinatubo, Philippines, in

4 Clicker Question How do ash-dominated eruptions commonly cause major death and destruction in cities? A. The ash gets blown high into the atmosphere and falls in huge amounts all around the globe. B. The volcano scores a direct hit on a city by erupting directly beneath it. C. Dense mixtures of ash and hot gases flow down the side of volcanoes. Volcano Hazards - Lahar (mudflow) Lahar is mixture of water, volcanic debris that flows downslope following river valleys; water from snow, ice on mountain slope (large stratovolcano at high elevation or in polar regions), or from eruption itself, or from rainfall Snow-covered Mt. Fuji, Japan Lahar from Mt. Ruapehu, New Zealand in 2007 Volcano Hazards - Lahar (mudflow) Lahars can move quickly or slowly, depending on amount of water. Fast lahars can be lethal (lahar from Nevada del Ruiz volcanic eruption in Columbia, South America in 1985 killed 25,000); slow-moving lahars can be very destructive (moving mud has great weight, force) Volcano Hazards - Lahar Video Lahars in Japan video (YouTube, 1:24) Lahar from 1985 Nevado del Ruiz eruption that devastated Armero, Colombia Lahar from 1982 eruption of Mt. Galunggung, Indonesia. Volcano Hazards - Tsunami Volcanic eruptions rarely create tsunamis; but Krakatoa eruption (between Java + Sumatra, Indonesia) created very large (35 m high) tsunami, which killed 36,000 Volcano Hazards - Effect on Climate Large, explosive ashfall eruptions can cause global cooling of up to several degrees for 1-2 years after eruption; climate change can cause crop failure + famine; cooling due to SO 2 gas-coated airborne volcanic ash, which reflects sunlight Painting of tsunami from Krakatau eruption of 1883 Map of Krakatau before (shaded) and after 1883 eruption Mt. Pinatubo s massive eruption in 1991 caused ~0.5 C global cooling for 1-2 years 4

5 Volcano Hazards - Effect on Climate 1816 is known as the Year Without a Summer, which was caused by massive eruption of Mt. Tambora in Indonesia in 1815; an estimated 90,000 deaths occurred world-wide due to famine Water is major gas released in volcanic eruptions, also can get other more harmful gases (e.g., CO 2, CO, SO 2, H 2 S, H 2 SO 4, HCl, HF) released Volcano Hazards - Gases In New England six inches of snow fell in June and every month of 1816 had a hard frost Volcanic Gas Hazards - Lake Nyos (1986) In 1986 in Cameroon (central Africa), 1,700 died overnight due to volcanoderived CO 2 gas that was released quickly from Lake Nyos (crater lake on top of dormant volcano). People died of asphyxiation (O 2 deprivation) when cloud of dense CO 2 gas came rolling down hillside. Volcanic Gas Hazards - Lake Nyos (1986) CO 2 gas from magma below seeped upward, dissolved in lake waters. Gas kept in solution by pressure of overlying water column. Something happened to overturn water (natural overturn, submarine landslide, underwater eruption, or EQ) and huge amount of CO 2 gas (80 million m 3 ) released, creating large waves when it broke water surface. Relatively heavy gas moved downslope and displaced O 2 in low areas. Predicting Volcanic Eruptions Magma movement often precedes eruptions: Prediction involves monitoring precursors ground swelling underground temperature earthquake activity composition of volcanic gases) Predicting Volcanic Eruptions Some success; Evacuation before Mt. Pinatubo s eruption in 1991 saved ~5,000 lives, $250 million property damage Much more progress is necessary 5

6 Mitigation of Volcanic Eruptions Mapping and Zoning; monitor precursors, warning and evacuation (history: 1595, 1845) Clicker Question Which of the following is NOT a method that scientists use to try to predict volcanic eruptions? A. They monitor (measure; watch) earthquakes. B. They monitor ground swelling. C. They monitor changes in volcanic gases emanated. D. They monitor changes in underground temperature. E. None of the above: The above are ALL methods that are used. Mitigation of Volcanic Eruptions - General monitor precursors Mitigation of Volcanic Eruptions Can we Control them? Explosive eruptions? Can t control, EVACUATE warning, evacuation Evacuation from Chaiten volcano, Chile, 2008 Mitigation of Volcanic Eruptions - Control? Can we control Non-explosive eruptions? Diversion using piles of earth, rubble (e.g., Mt. Etna; Heimaey, Iceland), chilling with water (e.g., Heimaeypersonal photo), bombing (e.g., Mt. Etna) 30 ft lava flow approaching diversion barrier (left), Mt Etna, 1983 Firefighters Divert Mt. Etna Lava Flow using water chilling in