KRAKATOA Hydro- Volcanic Explosion and Tsunami

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KRAKATOAHydro- VolcanicExplosionandTsunami
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Krakatoa

• Krakatoa exploded August 27, 1883 obliterated 5
  square miles leaving a crater 3.5 miles across
  and 200-300 meters deep.
• 33 ft high tsunami waves hit Anjer and Merak
  demolishing the towns and killing most of the
  people
• gt 10,000. In Merak wave rose to 135 ft ASL and
  moved 100 ton Coral blocks up on the shore.

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Krakatoa Tsunami

• Tsunami swept over 300 coastal towns and
  villages. Over 40,000 were killed by the tsunami
  waves.
• Sea withdrew at Bombay, India and killed one
  person in Sri Lanka.
• Tsunami produced by explosion and associated
  shock wave and pyroclastic flows.

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Krakatoa Before and After Explosion
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New Volcano Anak Krakatau - 1983
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Travel Time of Major Tsunami from 4th Explosion
and Collapse
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Area Flooded
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Max Run-up Heights (meters)
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Jakarta Tide GaugeBarographRecordshows
early arrival of the atmos pressure waves
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Tide Gauge Records from Atmospheric Pressure Waves
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HYDROVOLCANIC EXPLOSIONS

• Generated by Interaction of Magma with ground
  water.
• Called Surtseyan after 1963 eruption off Iceland.
• Water flashes to steam and expands explosively
• H2O(LIQUID) gt H2O(GAS) at constant volume has
  a 30 Kbar PRESSURE

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Modeling Hydrovolcanic Explosions

• Water described as an Explosive and a propagating
  detonation is modeled for hot liquid water going
  to gas.
• BKW steady state conditions of C-J state of 89
  kbar, 5900 m/sec, 0.75 cc/gm, 1100o K for liquid
  water with -46.3 kcal/mole Heat of Formation to
  model energy (19 kcal/mole) for hot lava heating
  water to 1100o K.

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Krakatoa ModelSpherical Geometry
2 0 Km -3
200 m
100 m Water
500 m Hot Spot
3 4
10 Km
AXIS
BASALT
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Hydrovolcanic Explosion
0.1 sec
0.3 sec
0.2 sec
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KRAKATOA HYDROVOLCANIC ERUPTION Density
Contours
0.5 Sec
0.4 Sec
0.4 Sec
0.5 Sec
0.7 Sec
0.6 Sec
0.7 Sec
0.6 Sec
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Krakatoa Hydrovolcanic EruptionDensity Contours
1.5 Sec
2.0 Sec
1.0 Sec

3.2 Sec
10.0 sec
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Krakatoa Hydrovolcanic EruptionX-velocity
contours
0.4 Sec
1 Sec
Note Strong Air shock
2 Sec
10 Sec
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Krakatoa Hydrovolcanic EruptionDensity Contours
First 0.67 sec
MOVIES AVAILABLE on NMWW DVD
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4 km 5 km
WAVE Profile
8 km
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TSUNAMI WAVE

• Radius Wave Height Period
• 4 km 130 meters 25 sec
• 5 km 48 meters 12 sec
• 8 km 7.5 meters 6 sec
• Inside the hydrovolcanic explosion at
• 1.5 km radius it expands up for more
• than 2 km with initial pressure gt25 kb

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Did it look like 1946 Bikini Shot?
21 Kt at 27 m depth Krakatoa 150-200
megatons
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Krakatoa

• The tsunamis had periods of less than 5 minutes
  and wavelength of less than 7 km thus rapidly
  decayed.
• The far field effects were negligible but
  recorded on tide gauges around the world. Caused
  by air shock propagating and coupling to the
  ocean.