Volcanism

• Evaluation Of Volcanic Risk In California
  • Population changes since 1915
    
    • Last violent eruption was Mt Lassen in 1915
      
      • California population was 2,800,000
        
    • 1999 population was >34,000,000
      
    • Some of this population has extended into volcanically hazardous areas
      
  • The 3 Most Dangerous Areas in California
    
    • Mt Shasta especially around Weed on west side - ashflows
      
    • Mt Lassen - mudflows and rock avalanches
      
    • Long Valley - Mammoth Mtn are
      
      
• How Volcanoes Cause Damage
  • Lava Flow Eruption
    • Kapoho, Hawaii example
      
      • The January 1960 flank eruption followed the December 1959 summit eruption
        
      • seismic swarms indicated the eruption was coming
        
      • January 13, 1960
        
      • Increased seismic activity
        
      • Cracks throughout town of Kapoho along Kapoho fault
        
      • Residents evacuate
        
      • 7:35 PM eruption began (fissure)
        
      • January 15, 1960
        
      • A’a flows 6 m thick builds out 100 m past original shoreline
        
      • Fissure eruptions produce fountains 200 – 275 m in height & creates a cinder cone
        
      • A’a flow reaches Higashi Pond
        
      • Town of Kapoho threatened
        
      • January 18-19, 1960
        
      • Higashi Pond fills with lava
        
      • Fountains of lava 365-425 m
        
      • Cinder cone partially collapses, sends lava towards village
        
      • Kuki`i-Kapoho Lava Barrier built
        
      • January 20, 1960
        
      • A’a lava flow destroys barrier
        
      • Second barrier built – lasted 7 days
        
      • Cinder Cone now 72 m high
        
      • January 25, 1960
        
        • Third barrier constructed (most massive)
          
        • Cinder Cone now 92 m high
          
        • Increased ash and pumice fall
          
      • January 27, 1960
        
        • All barriers failed
          
        • Town destroyed
          
      • January 30-31, 1960
        
        • Eruption slows and finally ceases by February 13th.
          
        • lava flows covered more than 10 km2
          
        • 2 km2 of new land
          
        • 122 million m3 lava erupted
          
        • 7.5 million m3 pyroclastic material erupted
          
        • 3rd largest Kilauea eruption in 20th century
          
  • Explosions and Ashflows
    
    • Ashflows are mixtures of hot gas and ash that move very quickly along the ground
      • Examples:
        
        • Mt. Vesuvius
          
        • Mt. Shasta
          
        • Mt. St. Helens
          
    • Mt. Vesuvius
      
      • 79 AD eruption
        
        • 20 mile (32 km) column of ash (estimated)
          
        • 1 cubic mile (4 cubic kilometers) of ash was erupted in about 19 hours
          
        • 10 feet (3 m) of tephra fell on Pompeii, burying the town
          
        • Herculaneum buried under 75 feet (23 m) of ash deposited by a pyroclastic flow
          
        • ~3,360 deaths
          
      • 1631
        
        • Mudflows and lava flows kill 3,500 people
          
      • 1875-1906
        
      • 1913-1944
        
        • March 1944 eruptiondestroyed the villages of San Sebastiano al Vesuvio, Massa di Somma and part of San Giorgio a Cremano
    • Mount Shasta, California
      
      • Second tallest in the Cascade Range
        
      • Erupted 11 times over last 3,400 years
        
        • 3 times last 750
          
        • Last eruption - 1786
      • Slopes covered with pyroclastic flows such as lahars
        
      • Event 300,000 years ago deposited 8x amount of debris as did the Mt. St. Helens 1980 event
        
    • Mt St. Helens
      
      • Eruption began in late March and climaxed May 18, 1980
        
      • 1 magnitude earthquake on nearby fault
        
      • A landslide followed and caused a huge explosion
        
        • 0.5 cubic miles of rock fell into Spirit Lake causing mudflows
          
        • Ashflow traveling 150 miles/hr traveled 18 miles devastating 215 sq miles (Temperature = 300°C)
          
  • Ashfall
    
    • Huge areas may be covered by volcanic ash
      
      • Crater Lake ash covers the entire Northwest
        
    • 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
        
  • Mudflows/Lahars
    • Ways that volcanoes make mudflows
      
      • Burn vegetation
        
      • Erupt ash
        
      • Produce rain
        
      • Melt glaciers or displace lakes
    • Lassen Volcanic Center
      
      • Comprised of:
        
        • Lassen Peak
          
        • Brokeoff stratovolcano (andesitic)
        • dacitic lava dome field
        • and peripheral small andesitic shield volcanoes and large lava flows
          
      • History
        
        • 600,000 y.– formation of Brokeoff volcano
          
        • 400,000 y.- dozen dacitic lava domes including Bumpass Mountain, Mount Helen, Ski Heil Peak, and
        • Reading Peak formed off north flank of Brokeoff
          
        • 28,000 y.– Lassen Peak formed
          
        • 1,100 – 1,000 y.– Chaos Crags formed
          
        • ~1600? – Cinder Cone formed
          
      • Lassen Peak
        
        • Volcano Type: Stratovolcano
          
        • Last Known Eruption: 1917
          
        • Summit Elevation: 3187 m (10,456 feet)
          
        • 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
    • St. Helens example
      
      • Mudflow was caused by the displaced Spirit Lake
        
      • Mudflow went 60 miles to the Columbia River
        
        • 45 million cubic yards sediment entered Columbia River
          
    • Nevada del Ruiz, Columbia
      
      • 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
          
    • Mt. Rainier
      
      • Mudflows threaten the towns and villages blow this dangerous volcano
        
      • Evacuation plans and drills are the key to survival
        
  • Gas
    • Cameroon – Lake Nyos
      
      • 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.
      • Maars in Oku volcanic field formed during an explosive eruption of carbon dioxide gas
        
      • Lake Nyos formed about 400 years ago
      • August of 1986
        
        • 1 km of CO2 released
          
        • ~1700 people killed up to 26 km away
          
      • August of 1984
        
        • smaller gas burst from Lake Monoun
          
        • 37 people killed
      • 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.

  • 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
      
  • Crater Lake
    
    • About 6,850 years ago Mount Mazama erupted
      
    • Caldera collapsed and produced Crater Lake
      
    • Eruption released ~12 cubic miles (50 cubic km) of magma to the surface
      
      • One of the largest eruptions in the last 10,000 years.
        
  • Yellowstone, Wyoming
    
    • A Hot Spot Volcano
      
    • Three very large eruptions in the last 2 million years
      
    • 2.0, 1.3, and 0.6 million years ago
      
    • Still active today
      
  • Long Valley Caldera, California
    
    • One of the largest Quaternary rhyolitic volcanic centers in North America
      
    • Caldera is 10 by 20 miles (15 by 30 km)
    • Volcanic activity began in the area ~3.6 million years ago
      
    • Catastrophic eruption ~730,000 years ago
      
      • Bishop Tuff
        
    • Mammoth Mountain formed along the southwest rim of Long Valley caldera from 200,000 to 50,000 years ago
    • Current issues
      
      • Carbon Dioxide and Helium Discharge from Mammoth Mountain
        
      • 1980 EQs resulted frommagma rising towardthe surface
        
      • Currently being monitored
        
  • Krakatoa
    
    • Inactive for 200 years before 1883
      
    • Eruption began in May and climaxed on August 26 & 27
      
      • VEI = 6
      • Lava, ash, and gas erupted
        
      • Ash covered neighboring islands
        
      • Pumice choked the Sunda Strait
        
    • Suddenly 10 sq miles collapsed
      
      • A strong Earthquake occurred
        
      • Sound could be heard 3000 miles away
        
      • Tsunami over 100 feet high killed 36,000 people in Java and Sumatra
  • Toba, Sumatra
    
    • Last erupted 74,000 years ago
      
      • The resultant caldera formed Lake Toba, 100 km long, 60 km wide
        
      • 3,000 km3 of ejected material
        
      • large quantities of SO2
    • Ash and SO2 ejected into the stratosphere reflects solar radiation back into space
      
    • Est. global cooling of 5ºC
      
    • 15 ºC in temperate & high latitudes
      
    • Genetic research on mitochondrial DNA
      
• The Eruption Of Thera - An Entire Civilization Destroyed
  • Located in the eastern Mediterranean
    
    • Southern most of Cycladic Islands
      
  • The Minoan Civilization
    
    • Minoans developed an advanced, maritime-based civilization in the eastern Mediterranean between 2000 and 1450 B.
    • Minoans were wealthy traders who lived in peace
      
    • Civilization was most developed on Crete
      
      • Palaces built at Knossos, Phaestos, and Zakros
        
      • Aqueducts and sewage systems
        
      • Good ports
        
      • Advanced art in painting and ceramics
        
    • Thera or the Minoans are probably Plato's lost Atlantis
      
      • From Plato's Timaeus - "But afterwards there occurred violent earthquakes and floods and in a single day and night of misfortune the island of Atlantis disappeared in the depth of the seFor which reason the sea in those parts is impassable because there is a shoal of mud in the way."
        
  • The Eruptions
    
    • The first historic eruption occurred in 1500 B.
      • Thera was evacuated permanently
        
    • Caldera collapse occurred on 1450
      • 32 sq miles collapsed into the Mediterranean
        
      • A tsunami spread through the Mediterranean hitting Crete perhaps 300 feet high
        
      • Earthquakes preceded and followed the eruption
        
      • Ash over 1 foot deep destroyed crops on Crete - starvation followed
        
      • All Minoan population centers were destroyed simultaneously
        
    • The Egyptians described the eruption - "For 9 days there was no exit from the palace and no one could see the face of his fellow. It is inconceivable what has happened in the land - to its whole extent confusion and terrible noise of tumult. Oh that the Earth would cease from noisThe towns are destroyeUpper Egypt suffered devastation. Blood everywherPestilence throughout the whole country. Men no longer sail to Byblos. What shall we do for cedar for our mummies and for the oils with which the chiefs are embalmed as far as the country of the Cretans? They come no morThe sun is covered and does not shine to the sight of men. Life is no longer possible when the sun is concealed behind the clouds. Ra has turned his face from mankinIf only it would shine, even for one hour! No one knows when it is midday; One's shadow is not discerniblThe sun in the heavens resembles the moon."
      
  • The Mycenaeans rose to rule the Mediterranean
    
    • Trade collapsed as piracy took over
      
    • Agamemnon led a prolonged war against Troy around 1250 B.
      • Mycennaean resources were greatly deplete
      • Agememnon was murdered by his wife upon return to Mycenae
        
  • Dorian Barbarians conquered the Mycenaeans around 1100 B.
    • Greece retreated to Stone Age conditions similar to the year 3000 B.
      • The Archean period began

LINKS

• California
  • Long Valley Caldera and Mono-Inyo Craters Volcanic Field, California
• Cameroon
  • Using Science to Solve Problems: The Killer Lakes of Cameroon
  • Volcanic Lakes and Gas Releases
• Columbia
  • CVO - Nevado del Ruiz, Colombia
  • Nevado del Ruiz, Colombia
• Greece
  • The Eruption of Thera
• Hawai'i
  • The 1960 Kapoho Eruption of Kilauea Volcano, Hawai`i
  • Kilauea Volcano
  • Volcanic and Seismic Hazards on the Island of Hawaii: Volcanic Hazards
• Kratatoa
  • THE EXPLOSION OF KRAKATOA MOUNTAIN
  • The Krakatoa Stories
  • Krakatau, Sundra strait
  • What happened in the Krakatoa eruption in the 1800's?
• Oregon
  • Crater Lake
• Washington
  • CVO - Mount Rainier, Washington
  • History of Landslides and Debris Flows at Mount Rainier, Washington
  • Mount Rainier, Washington
  • Mt. Rainier Mudflow (lahar) Warning System
  • Mount St. Helens, Washington - May 18, 1980 Eruption
  • NOAA Images - The Eruption of Mount Saint Helens
• Yellowstone
  • The Snake River Plain and the Yellowstone Hot Spot
• General
  • Deadliest Volcanic Eruptions Since 1500 A.D.
  • Potentially Active Volcanoes of the Western United States
  • Video Clips on VolcanoWorld
  • Volcanoes in the North and Central American Region
  • World Organization of Volcano Observatories (WOVO) - North America and the West Indies
    • Alaska Volcano Observatory
    • David Johnston Cascades Volcano Observatory
    • The Hawaiian Volcano Observatory
    • Instituto de Geofisica, Mexico
    • Centro Universitario de Investigacion en Ciencias de la Tierra (CUICT) - Colima, Mexico
    • Observatoire Volcanologique de la Soufriere, Guadeloupe
    • Observatoire Volcanologique de la Montagne Pele
    • Seismic Research Unit, University of the West Indies

Evaluation Of Volcanic Risk In California | How Volcanoes Cause Damage | The Eruption Of Thera - An Entire Civilization Destroyed | Links