Volcanic Hazards 1 48 Volcanic Hazards Direct Lava

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Volcanic Hazards 1 / 48

Volcanic Hazards 1 / 48

Volcanic Hazards • Direct – – – – Lava Flows Eruptions / Explosions Pyroclastic

Volcanic Hazards • Direct – – – – Lava Flows Eruptions / Explosions Pyroclastic Flows Ashfall Mudflows/Lahars Gas Caldera Collapse Tsunami • Indirect – Famine – Climate change 2 / 48

Volcanic Hazards • Volcano Fatalities Last 500 Years Type of Event 275, 000 deaths

Volcanic Hazards • Volcano Fatalities Last 500 Years Type of Event 275, 000 deaths 530 Volcanic Events Pyroclastic flow 29% 15% Tsunami 21% 5% Lahar 15 % 17 % Indirect (famine) 23 % 5% Gas 1% 4% Lava flow <1 % 4% Pyroclastic fall (bombs) 2% 21 % Debris avalanche 2% 3% Flood 1% 2% Earthquakes <1 % 2% Lighting <1 % 1% Unknown 7% 20 % 3 / 48

Lava Flows • Nyiragongo, Zaire 2002 – In East African Rift Zone – Lavas

Lava Flows • Nyiragongo, Zaire 2002 – In East African Rift Zone – Lavas unusually low in Si. O 2 – Flowed rapidly down the slope, through the city of Goma to Lake Kivu – 45 people killed 4 / 48

Lava Flows • Iceland – Icelandic-type Eruptions • AKA fissure eruptions • Peaceful •

Lava Flows • Iceland – Icelandic-type Eruptions • AKA fissure eruptions • Peaceful • Basaltic magma 5 / 48

Lava Flows • Iceland – Lava Flows of 1973 • 1/23/73 fissure opened up

Lava Flows • Iceland – Lava Flows of 1973 • 1/23/73 fissure opened up near the town of Vestmannaeyjar (pop. 5, 300) • Lava flows and pyroclastic debris threatened to bury the town • Townspeople sprayed seawater on lava, diverted the flow • Town saved 6 / 48

Heimaey - 1973 Eruption 7 / 48

Heimaey - 1973 Eruption 7 / 48

Eruptions / Explosions • Lassen Peak, California, 1914 -17 – Lava Dome – Formed

Eruptions / Explosions • Lassen Peak, California, 1914 -17 – Lava Dome – Formed after Mt. Tehama became extinct & eroded away – Part of the Lassen dome field 8 / 48

Eruptions / Explosions • Lassen Peak, California, 1914 -17 – Began erupting May 1914

Eruptions / Explosions • Lassen Peak, California, 1914 -17 – Began erupting May 1914 • July 18, 1914 – Huge ash cloud ejected 3, 350 m into atmosphere • May 16 – 18, 1915 – Lava oozed out of crater – Red glow from the hot lava visible at night 34 kilometers away. • May 19, 1915 – avalanche of hot rocks combined with snow and triggered a lahar that extended more than 50 km • Eruptions continued through 1917, then ceased 9 / 48

The northeast flank of Lassen Peak photographed on 22 May 1915 by B. F.

The northeast flank of Lassen Peak photographed on 22 May 1915 by B. F. Loomis from the position marked on Fig. 5, several hours prior to the 22 May eruptions. Peaks labeled A and B can be used as registration points when comparing Fig. 2 a and Fig. 3. The label "hot rock" was written on the original glass plate by Loomis over the image of a piece of 19 May dacite lava and alludes to the fact that the rock was still too hot to touch ~48 hr after it was erupted. From: http: //barsoom. msss. com/earth/lassen/

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Eruptions / Explosions • Mount St. Helens, Washington, 1980 – March 20, 1980 –

Eruptions / Explosions • Mount St. Helens, Washington, 1980 – March 20, 1980 – Harmonic tremors began • Lava dome pushed into the north flank, over-steepening it – May 18, 1980 • 5. 1 earthquake on nearby fault • Caused a massive landslide on the unstable north side • Removal of overburden released pressure and caused the eruption • http: //pubs. usgs. gov/publications/msh/catastrophic. html – 5 -10 fatalities, $12. 3 million in damage 13 / 48

Mt. St. Helens before the 1980 eruption 14 / 48

Mt. St. Helens before the 1980 eruption 14 / 48

Mt. St. Helens following the 1980 eruption 15 / 48

Mt. St. Helens following the 1980 eruption 15 / 48

Mt. St. Helens New Dome Rock Glacier Vent 1980 -1986 Dome http: //earthobservatory. nasa.

Mt. St. Helens New Dome Rock Glacier Vent 1980 -1986 Dome http: //earthobservatory. nasa. gov/Newsroom/New. Images/images. php 3? img_id=16721 16 / 48

Mt. St. Helens, October 1, 2004 http: //www. nasa. gov/vision/earth/lookingatearth/mshelenslidar. html 17 / 48

Mt. St. Helens, October 1, 2004 http: //www. nasa. gov/vision/earth/lookingatearth/mshelenslidar. html 17 / 48

Mt. St. Helens Blast Zone June 28, 2012 © Sonjia Leyva, 2012 18 /

Mt. St. Helens Blast Zone June 28, 2012 © Sonjia Leyva, 2012 18 / 48

Comparison of Large Volcanic Eruptions 19 / 48

Comparison of Large Volcanic Eruptions 19 / 48

Pyroclastic Flows • Mount St. Helens, Washington, 1980 – Pyroclastic flows (Nueé ardentés) are

Pyroclastic Flows • Mount St. Helens, Washington, 1980 – Pyroclastic flows (Nueé ardentés) are mixtures of hot gas and ash that move very quickly along the ground 20 / 48

Pyroclastic Flows • • • Mount Mayon, Philippines, 1968 El Chichon, Mexico, 1982 Mount

Pyroclastic Flows • • • Mount Mayon, Philippines, 1968 El Chichon, Mexico, 1982 Mount Unzen, Japan, 1991 Mont Pelee, 1902 -1903, 1929 -1932 Mont Pelee, Martinique, 1902 Krakatau, Indonesia, 1883 21 / 48

Pyroclastic Flows • Mount Shasta, California – Second tallest in the Cascade Range –

Pyroclastic Flows • Mount Shasta, California – Second tallest in the Cascade Range – Erupted 11 times over last 3, 400 years • 3 times last 750 • Last eruption - 1786 22 / 48

Pyroclastic Flows • Mount Shasta, California – Slopes covered with pyroclastic flows such as

Pyroclastic Flows • Mount Shasta, California – Slopes covered with pyroclastic flows such as lahars – Event 300, 000 years ago deposited 8 x amount of debris as did the Mt. St. Helens 1980 event 23 / 48

Mt. Shasta – November 1998 24 / 48

Mt. Shasta – November 1998 24 / 48

Ashfall • Huge areas may be covered by volcanic ash • Damage to urban

Ashfall • Huge areas may be covered by volcanic ash • Damage to urban areas can be enormous – Crops are destroyed threatening the food supply – Public water contaminated – Buildings collapse under weight of ash – Air travel disrupted 25 / 48

Ashfall 26 / 48

Ashfall 26 / 48

Lahars (Volcanic Mudflows) • Ways that volcanoes make lahars – Add water + volcanic

Lahars (Volcanic Mudflows) • Ways that volcanoes make lahars – Add water + volcanic material = lahar – Water sources: • Melt glaciers • Displace lakes • Rain – Material • Ash • Soil • Burnt vegetation 27 / 48

Lahars (Volcanic Mudflows) • Kelut, Indonesia, 1586, 1919 – Large crater lake at summit

Lahars (Volcanic Mudflows) • Kelut, Indonesia, 1586, 1919 – Large crater lake at summit – Pyroclastic eruptions + water from lake = lahar • Eruptions make for fertile soil, so heavily populated – Last eruption: 1990 • VEI=4 • produced a large cloud and heavy tephra fall • 32 people killed 28 / 48

Lahars (Volcanic Mudflows) • Mount St. Helens, Washington, 1980 – Mudflow was caused by

Lahars (Volcanic Mudflows) • Mount St. Helens, Washington, 1980 – Mudflow was caused by the displaced Spirit Lake • Mudflow went 60 miles to the Columbia River • 45 million cubic yards sediment entered Columbia River 29 / 48

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Surface details of the debris (mud) flow on the North Fork of the Toutle

Surface details of the debris (mud) flow on the North Fork of the Toutle River near Coldwater Creek (see map). There is approximately 50 feet of relief between the pond and the mudflow surface. http: //www. iris. edu/gifs/slides/sthelens/slideshow/pages/16. htm Devastation occurring at the log camp on the South Fork Toutle River - overturned trucks and caterpillers. http: //vulcan. wr. usgs. gov/Volcanoes/MSH/Images/may 18_devasta tion. html 31 / 48

Lahars (Volcanic Mudflows) • Nevado Del Ruiz, Colombia, 1985 – 2 eruptions on Nov

Lahars (Volcanic Mudflows) • Nevado Del Ruiz, Colombia, 1985 – 2 eruptions on Nov 13, 1985 melted the summit glaciers – Mudflows travelled in all directions from the summit – Mud traveling 30 mph and 50 feet deep buries Amero 30 miles away – 25, 000 killed 32 / 48

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Lahars (Volcanic Mudflows) • Mount Rainier, Washington – Mudflows threaten the towns and villages

Lahars (Volcanic Mudflows) • Mount Rainier, Washington – Mudflows threaten the towns and villages blow this dangerous volcano – Evacuation plans and drills are the key to survival 34 / 48

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Gas • Cameroon – Type of volcanism: Maar • A volcanic crater that is

Gas • Cameroon – Type of volcanism: Maar • A volcanic crater that is produced by an explosion in an area of low relief, is generally more or less circular, and often contains a lake, pond, or marsh. (http: //volcano. und. nodak. edu/vwdocs/glossary. html) Landsat image of Lake Nyos processed by Sarah Sherman, April 2000. 36 / 48

Gas • Cameroon – August of 1986 Lake Nyos • 1 km of CO

Gas • Cameroon – August of 1986 Lake Nyos • 1 km of CO 2 released • ~1700 people killed up to 26 km away from the lake – August of 1984 • smaller gas burst from Lake Monoun • 37 people killed 37 / 48

Gas • Cameroon – Only three lakes in the world are known to contain

Gas • Cameroon – Only three lakes in the world are known to contain high concentrations of dissolved gas in their bottom waters: • Lakes Nyos and Monoun in Cameroon • and Lake Kivu in East Africa. – Only Lakes Nyos and Monoun are known to have recently released gas resulting in the loss of human life. Using Science to Solve Problems: The Killer Lakes of Cameroon By Dr. George Kling 38 / 48

Gas Release (CO 2) Lake Nyos, Cameroon 39 / 48

Gas Release (CO 2) Lake Nyos, Cameroon 39 / 48

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Caldera Collapse • Believed to be caused by magma evacuating its chamber • Caldera

Caldera Collapse • Believed to be caused by magma evacuating its chamber • Caldera eruptions in New Zealand could damage cities like Auckland • Famous (or infamous) collapsed calderas: – Crater Lake, Oregon – Yellowstone, Wyoming – Long Valley Caldera, California – Krakatoa & Toba, Indonesia 42 / 48

Tsunami • Mt. Unzen, Japan 1792 – Earthquake caused lava dome to collapse –

Tsunami • Mt. Unzen, Japan 1792 – Earthquake caused lava dome to collapse – Traveled 6. 4 km to ocean, caused tsunami – 15, 000 people killed 43 / 48

Southeastern view of Unzen Volcano from air Taken by Nakagasaki Photo Service Co. LTD

Southeastern view of Unzen Volcano from air Taken by Nakagasaki Photo Service Co. LTD (Oct. 1992) http: //hakone. eri. utokyo. ac. jp/unzen/bgd. htm 44 / 48

Indirect – Famine • Laki, Iceland Fissure Eruption of 1783 – Large quantities of

Indirect – Famine • Laki, Iceland Fissure Eruption of 1783 – Large quantities of SO 2 and fluorine – Killed • 75% of Iceland’s sheep & horses • 50% of Iceland’s cattle • 20% of Iceland’s population (due to famine) 45 / 48

Indirect – Famine • Tambora, Indonesia, 1815 – Pyroclastic fallout destroyed crops in Indonesia

Indirect – Famine • Tambora, Indonesia, 1815 – Pyroclastic fallout destroyed crops in Indonesia – Affected global climate – 1816 “year without a summer” 46 / 48

Volcano Monitoring and Warning • Long Valley, California, 1982 • Mount Pinatubo, Philippines, 1991

Volcano Monitoring and Warning • Long Valley, California, 1982 • Mount Pinatubo, Philippines, 1991 47 / 48

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