Chile earthquake and tsunami
Magnitude 8.8;
hypocenter 21 miles
Tsunami
Deep-ocean Assessment and
Reporting of Tsunami
Changed the
planet’s axis by
three inches
•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)
Chile: M 8.8
earthquake
Chile: aftershocks
Magnitudes: 6, 5.1, 4.9
Tsunami warning
Predicting volcanic eruptions
and reducing the risk
What can scientists do to
reduce volcanic risk?
Mitigation: measures to reduce
risk
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Understanding the potential hazards
Hazard maps
Monitoring
Emergency plan in place and practiced
Education of government officials and
public
This process begins with the
gathering of scientific information
Understanding the Past
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The eruptive history is very
important.
Ancient volcanic deposits are dated
to determine frequency of eruptions.
An understanding of the potential
hazard
Understanding of hazards: provide
definition and potential location
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People will evacuate
when there is an
understanding of the
potential destruction
from a hazard.
Successful prediction of Mt.
Pinatubo, 1991
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The Philippine
government used volcanic
hazard videos and other
information to educate
the public
Successful evacuation
Disaster Nevado del Ruiz volcano,
Columbia, 1985
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The people of Armero did not understand the potential
hazards of a lahar
Government officials knew about the potential hazard
23,000 fatalities
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
Lassen Peak, Hazard Map
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Vents that have
produced eruptions
Yellow- lava flow
zones
Gold- ash fall zone
Orange-combined
Pink-mudflows
Aqua- floods
Monitoring Precursors
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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
Monitoring methods
Monitoring Volcanoes
Ground Deformation
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Movement of magma into the system tends to inflate the
volcano’s surface
Tiltmeters
Global Positioning Stations (GPS)
Radar interferometry- satellite
Deformation
Tiltmeter
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Direct
measurements are
made when the
volcano is increasing
in precursor activity
Global Positioning Satellites record vertical and
horizontal movement of the volcano
Monitoring Volcanoes
Seismicity
Mt. St. Helens
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Magma fractures cooler rock causing
earthquakes
An increase in the number of earthquakes may
indicate an imminent eruption
Seismometer
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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
Monitoring the Long Valley
Caldera
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Ground deformation
Resurgent dome
grew is 80
centimeters from the
late 1970’s to 1999
minor subsidence
since 1999
Monitoring the Long Valley
Caldera
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Seismicity averages
5-10 earthquakes
per day since 1999
Occasionally swarms
of earthquakes
cause alarm (200300/week)
generally less than
M=2
Mt. St. Helens
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Seismic activity
increased in 2005
Increased monitoring
of activity
Seismicity
Visual inspections
Gas emissions
Mt. St. Helens
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Alert level 2: activity
increasing that lead to
a hazardous volcanic
eruption
Aviation level orangeash to 30,000 feet,
traveling 100 miles
Seismicity
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With more than three
stations the initial rupture
of the earthquake is
located
Outlining the size and
location of the magma
chamber
Mt. St Helens
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Green dots represent activity in the
past 24 hours.
Gas Emissions: as magma
ascends, decompression
melting releases gas
Sulfur dioxide cloud, three
hours after eruption
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Direct and indirect measurements
Increase in gas emissions may
indicate an imminent eruption
Mt. St. Helens
Volcanic watch
Monitoring the Long Valley
Caldera
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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
Gas Emissions
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Direct sampling is
completed by
collecting the gas in
a liquid
Analysis is done at a
laboratory
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
Thermal Change indicates magma moving closer to the
surface
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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
Lahar Warning System
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Sensors detect high frequency vibrations
produced by lahars moving down a stream
channel
Sensors are placed downstream from volcano
but upstream from population
Warning System
Warning System
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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
Aviation Warning
System
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Green: normal activity
Yellow: exhibiting signs of elevated unrest
Orange: heightened unrest with increased
likelihood of eruption (specify ash plume
height)
Red: eruption’s forecast to be imminent
with significant emission of ash into the
atmosphere (specify ash plume height)
Educating the Public
Communication
Most important: think of the disasters in
the past 6 years
Volcanic Disaster Assistance
Program
Volcanic Disaster Assistance
Program
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The primary purpose is to save lives in
developing countries.
Works with the Office of /Foreign disaster
Assistance
U.S. Agency for International Development
Volcanic Disaster Assistance
Program
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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.
Communication to Public
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Increase in seismic
activity in 1996
Alaska
Prevent evacuation of
1,000 residents
Prevent closing of
fishing industry
The eruption of Rabaul, Papua New
Guinea, September, 1994.
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Residents who witnessed the 1937 eruption
explained what occurred
Education of the local population through
community groups
Successful evacuation due to following the plan
Real time monitoring
Successful Prediction
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Mount Pinatubo, 1991
Approximately 330,000 people
evacuated prior to the eruption
Evaluation of Risk
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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
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
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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
Hazard=based on the Volcanic Explosivity
Index- VEI
Volcanic Explosivity Index
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Volume of material
Eruption column
Plinian: 5-7; 1993 Lascar Volcano, Chile
height
Eruptive style
How long the
Hawaiian: 0-2
major eruptive
burst lasted
Tambora eruption, 1815: VEI 7
Evaluation of
Risk
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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
Vesuvius Erupts
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Computer
simulations help
understand which
areas would be
affected first
Those
communities
should be
evacuated first
Mt. Vesuvius, Areas of Risk
Emergency
plan assumes
that there can
be a 20 day
warning
Without warning
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Estimated 15-20,000 casualties
What do you think?
1944
eruption
Mitigation
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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