Yellowstone supervolcano

Yellowstone supervolcano

1. Why?

   • lies on a hotspot
     • magma chamber 80km long / 40km wide / 8 km deep
       • 20-25,000cubic km of magma
       • contains 5x the magam needed to make a supervolcano = 5,000cubic km of magma

2. What?

   • cataclismic eruption
     • 1000+ cubic km material (magma and pyroclastic material)
       • immensely violent VEI 8
         • 100m thick ash and tephra
       • less violent basaltic flood
   • Caldera - flat and sunken crater

3. When?

   • every 600,000 yrs
   • last one c.640,000 yrs ago

4. Where?

   • Yelowstone Park,
     • Norris Geyser Basin
       • 2003 - increase in ground temps to 100C / more frequent geyser eruptions / more gases from vents / 5 bison died of hydrogen sulphide & carbon dioxide poisoning / trees died / closed to public
       • uplift due to magma rising or gas levels increasing

5. So what?

   • immediate effects
     • extinguish all life forms withing 200km radius
     • further afield: transport, livestock power lines and water affected
     • 40-50 km high cloud of ash
     • equivalent to 1000 hiroshima bombs a second
     • more rainfall - lahars. could cause 50,000 deaths
     • 15cm ash within 1,000km: loss of homes / roof colapse and 1 in 3 people die.
     • Ash reaches Europe in 5 days
   • longer term effects
     • onset of glaciation - winter temps drop by 1-2.5 C
     • fall in agricultural yield -
       • increase in food prices
         • famine
         • conflict
     • sulphurous cloak around world in 3 wks.
     • drop of 12C in high latitudes - permanent snow.
     • Tropics - drop of 15C / failure of monsoon. 40% world pop facing starvation