Chile earthquake and tsunami

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Chile earthquake and tsunami

• Magnitude 8.8 hypocenter 21 miles

• Tsunami

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Deep-ocean Assessment and Reporting of Tsunami
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Changed the planets axis by three inches
Chile M 8.8 earthquake

• Large mass of rock moved
• Nearby island uplifted 2 feet
• Steep sloping subduction zone
• Each day should be 1.26 microsecond shorter
  (hundredth of a second)

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Chile aftershocks

• Magnitudes 6, 5.1, 4.9

• Tsunami warning

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Predicting volcanic eruptions and reducing the
risk
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What can scientists do to reduce volcanic risk?
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Mitigation measures to reduce risk

• Understanding the potential hazards
• Hazard maps
• Monitoring
• Emergency plan in place and practiced
• Education of government officials and public

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This process begins with the gathering of
scientific information
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Understanding the Past

• The eruptive history is very important.
• Ancient volcanic deposits are dated to determine
  frequency of eruptions.

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An understanding of the potential hazard
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Understanding of hazards provide definition and
potential location

• People will evacuate when there is an
  understanding of the potential destruction from a
  hazard.

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Successful prediction of Mt. Pinatubo, 1991

• The Philippine government used volcanic hazard
  videos and other information to educate the
  public
• Successful evacuation

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Disaster Nevado del Ruiz volcano, Columbia, 1985

• The people of Armero did not understand the
  potential hazards of a lahar
• Government officials knew about the potential
  hazard
• 23,000 fatalities

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Map ancient volcanic deposits.
Hazard Map of Mt. Rainier map indicates previous
lahar and pyroclastic flows
Results where one would expect these hazards to
occur in the future
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Lassen Peak, Hazard Map

• Vents that have produced eruptions
• Yellow- lava flow zones
• Gold- ash fall zone
• Orange-combined
• Pink-mudflows
• Aqua- floods

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Monitoring Precursors

• Physical changes are known to precede a volcanic
  eruption.
• Name changes in volcanic activity. These changes
  are called precursors.

• Seismicity
• Deformation
• Snow melt
• Water levels and chemistry
• Gas emission
• Small eruptions

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Monitoring methods
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Monitoring VolcanoesGround Deformation

• Movement of magma into the system tends to
  inflate the volcanos surface
• Tiltmeters
• Global Positioning Stations (GPS)
• Radar interferometry- satellite

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Deformation
Tiltmeter

• Direct measurements are made when the volcano is
  increasing in precursor activity

Global Positioning Satellites record vertical and
horizontal movement of the volcano
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Monitoring VolcanoesSeismicity
Mt. St. Helens

• Magma fractures cooler rock causing earthquakes
• An increase in the number of earthquakes may
  indicate an imminent eruption

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Seismometer

• Seismic waves move through the crust and reach
  the seismometer
• The seismometer records the strength and type of
  movement
• The information is sent to a station and recorded
  through radio waves or satellite communication

Seismometer placed near Mt. St. Helens
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Monitoring the Long Valley Caldera

• Ground deformation
• Resurgent dome grew is 80 centimeters from the
  late 1970s to 1999
• minor subsidence since 1999

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Monitoring the Long Valley Caldera

• Seismicity averages 5-10 earthquakes per day
  since 1999
• Occasionally swarms of earthquakes cause alarm
  (200-300/week)
• generally less than M2

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Mt. St. Helens

• Seismic activity increased in 2005
• Increased monitoring of activity
• Seismicity
• Visual inspections
• Gas emissions

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Mt. St. Helens

• Alert level 2 activity increasing that lead to a
  hazardous volcanic eruption
• Aviation level orange- ash to 30,000 feet,
  traveling 100 miles

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Seismicity

• With more than three stations the initial rupture
  of the earthquake is located
• Outlining the size and location of the magma
  chamber

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Mt. St Helens

• Green dots represent activity in the past 24
  hours.

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Gas Emissions as magma ascends, decompression
melting releases gas
Sulfur dioxide cloud, three hours after eruption

• Direct and indirect measurements
• Increase in gas emissions may indicate an
  imminent eruption

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Mt. St. Helens
Volcanic watch
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Monitoring the Long Valley Caldera

• Carbon dioxide escape from the magma chamber
• Associated with faults that act as pathways
• 50-150 tons per day since 1996
• level remains the same
• Horseshoe lake

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Gas Emissions

• Direct sampling is completed by collecting the
  gas in a liquid
• Analysis is done at a laboratory

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Satellite images can monitor movement of ash in
the atmosphere. Ash abrades windows and can cause
engine failure
Composite satellite image of ash produced from
Mt. Spur, Alaska over a one week period
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Thermal Change indicates magma moving closer to
the surface

• Satellite sensors are able to detect increased
  temperatures before an eruption
• Used for remote active volcanoes or if seismicity
  does not precede an eruption

Pavlov Volcano, Alaska
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Lahar Warning System

• Sensors detect high frequency vibrations produced
  by lahars moving down a stream channel
• Sensors are placed downstream from volcano but
  upstream from population

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Warning System
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Warning System

• Normal Typical background activity non-eruptive
  state
• Advisory Elevated unrest above known background
  activity
• Watch Heightened/escalating unrest with
  increased potential for eruptive activity
• Warning Highly hazardous eruption underway or
  imminent

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Aviation Warning System

• Green normal activity
• Yellow exhibiting signs of elevated unrest
• Orange heightened unrest with increased
  likelihood of eruption (specify ash plume height)
• Red eruptions forecast to be imminent with
  significant emission of ash into the atmosphere
  (specify ash plume height)

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Educating the Public
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Communication
Most important think of the disasters in the
past 6 years
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Volcanic Disaster Assistance Program
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Volcanic Disaster Assistance Program

• The primary purpose is to save lives in
  developing countries.
• Works with the Office of /Foreign disaster
  Assistance
• U.S. Agency for International Development

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Volcanic Disaster Assistance Program

• The Volcanic Disaster Assistance Program was
  developed after the 1985 eruption of Nevada del
  Ruiz.
• Since 1986, the response team organized and
  operated by the U.S.G.S. responds globally to
  eminent probable volcanic eruptions.

Nevada del Ruiz lahar that killed 23.000 people.
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Communication to Public

• Increase in seismic activity in 1996
• Alaska
• Prevent evacuation of 1,000 residents
• Prevent closing of fishing industry

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The eruption of Rabaul, Papua New Guinea,
September, 1994.

• Residents who witnessed the 1937 eruption
  explained what occurred
• Education of the local population through
  community groups
• Successful evacuation due to following the plan

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Real time monitoring
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Successful Prediction

• Mount Pinatubo, 1991

Approximately 330,000 people evacuated prior to
the eruption
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Evaluation of Risk

• Zones of highest to lowest risk should be
  identified
• Urban planning should take in account the areas
  of highest risk
• These areas should be evacuated first

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Risk

• Applying the Volcano Explosivity Index
• Mt. Pinatubo- 6-7
• Amount of property damage
• Population
• This equates to the amount of risk

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Evaluation of Volcanic Risk

• United Nations Educational, Scientific and
  Cultural Organization-UNESCO
• Risk(value)x(vulnerability)x(hazard)
• Value of lives, monetary goods in area
• Vulnerability of lives or goods likely to be
  lost in a given event
• Hazardbased on the Volcanic Explosivity Index-
  VEI

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Volcanic Explosivity Index

• Volume of material
• Eruption column height
• Eruptive style
• How long the major eruptive burst lasted

Plinian 5-7 1993 Lascar Volcano, Chile
Hawaiian 0-2
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Tambora eruption, 1815 VEI 7
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Evaluation of Risk

• Mt. Vesuvius produced a VEI 5 eruption in 79 CE.
• There are now 3 million people living on and near
  this volcano.
• Less than 1 chance for another eruption this
  size in the next 10 years
• High risk coefficient due to the high population
  density

Mt. Vesuvius, Pliny
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Vesuvius Erupts

• Computer simulations help understand which areas
  would be affected first
• Those communities should be evacuated first

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Mt. Vesuvius, Areas of Risk
Emergency plan assumes that there can be a 20 day
warning
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Without warning

• Estimated 15-20,000 casualties
• What do you think?

1944 eruption
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Mitigation

• Understanding the potential hazards
• Hazard maps
• Monitoring
• Emergency plan in place and practiced
• Education of government officials and public
• Communication clear between scientists,
  government officials and the public