Watch 2.25 min video footage of the plaster cast people of Pompei
Highlight that these people were instantly turned into plaster casts by the pyroclastic flow.
Watch video on the landslide after Mt St Helen’s eruption
2 min vid
Watch FOX news rpt on Iceland volcanic eruption grounding flights http://www.youtube.com/watch?v=RCWp1fGP_6M 3 mins AlJazeera clip on Heathrow opening and passengers stranded in SGP flying back http://www.youtube.com/watch?v=WfcTMlP5UTA
Issue Ex 5 on the negative effects of living near a volcano
Watch view of destruction post earthquake in Christchurch (2min) http://www.youtube.com/watch?v=opsiKirDfdE News report on Christchurch massive quake (response by gvt) (1:30 min) http://www.youtube.com/watch?v=wBq1-qZWmhM
Watch NZ video on Earthquake Preparedness (4min) http://www.youtube.com/watch?v=-a7T9Uf-JB4
Watch clip on tremors in SGP (who is our buffer?) Indonesia!
Watch video of damage of 7.2 Christchurch earthquake 2011. End of vid, ask students to think if it had happened in the middle of the night, what might the death toll be looking at the look of the damage in the video?
Watch short clip on liquefaction (45 secs) http://www.youtube.com/watch?v=qmVYbjiNWds
Alternate vid (forward to 50s) to watch the video of liquefaction. http://www.youtube.com/watch?v=PwvvYxSZ7PI
Pic on left (vid) that shows 2004 Tsunami at Thailand http://www.youtube.com/watch?v=ntIwawAusDE
Pic on right (vid) of Bandar Aceh (initial earthquake and subsequent tsunami) 7 min. Worth watching! http://www.youtube.com/watch?v=ht_ZpSuJ6A4
Watch 3 min vid on Japanese earthquake http://abcnews.go.com/Archives/video/jan-17-1995-earthquake-japan-9421417
• The rock layers on the crust are
constantly exposed to pressure
• When they are compressed, they
fold, forming fold mountains.
• To upfold is called the anticline and
downfold is called the syncline.
• The major ranges are along
convergent plate boundaries
• The rocky mountains
• Swiss Alps
• Pg 22
• Near divergent plate boundaries, plates pull
apart, causing land displacement.
• The downward displacement forms rift
• Found commonly along divergent boundaries
• Also called Graben
• East African Rift Valley
• When sections of the crust are pulled
apart by tensional force, some parts are
• The downward displaced areas are the
• The blocks left behind form block
mountains with steep sides.
• Also called Horst
• Landform formed by magma ejected from the
• Magma builds up in the earth’s crust to form a
• With repeated layering of ejected magma, the
volcano grows in height
• Found a divergent and convergent plate
boundaries where there is subduction.
• Vents are openings in the earth’s surface
with a pipe leading into the magma
• When magma is ejected onto the
surface, it is called lava. There is no
change in composition.
• Vulcanicity refers to the upward
movement of magma in the crust and
onto the surface.
Let’s take a short Brain Break
• Take a look at the
video on Mt St
Helens in America
• Half the volcano
was blown off in the
• The stickiness of the lava
• The resistance of the lava to flowing
• High viscosity flows slowly
• Low viscosity flows quickly
• Viscosity of the lava determines the
• Gentle sloping sides and a broad
• Low-silica lava (low viscosity) present
• Lava flow is fast, spreading out
• Subsequent layering leads to wide
base with low overall height.
• Mount Washington in America
• Developed from successive eruptions.
• Ash and lava (coarse fragment) accumulate over
• Layers of ash are locked in by subsequent layers of
• Tall volcanoes with concave bases formed.
• Secondary cones may develop as magma from the
vent seeps into the sides of the cone and erupts.
• Pyroclastic flow common
– Hot rock fragments and superheated gases.
• Mount Pinatubo, Philippines
Distribution of volcanoes
• Pacific Ring of Fire is the most active volcanic
• Many earthquakes and volcanic eruptions
occur along the ring of fire
• Ring is along several converging plates (Pacific,
Nazca, Philippines, Australian and Eurasian
• Volcanoes can also form where plates diverge.
• Pg 29
• Volcanoes fall into 3 states
• Constant volcanic activity
• Currently undergoing eruption or
are expected to erupt in the
• Mt Pinatubo, Philippines; Mt St
• Currently inactive but may erupt
in the near future
• Prolonged period of no volcanic
• Inner magma chamber still hot
• Mt Fuji, Japan
• Volcanoes without current seismic
• No geological evidence of eruption in
the past thousands of years.
• Almost no risk of eruption.
• Lake Toba, Indonesia
Risks of living near volcanic areas
1.Destruction by volcanic
4.Effects on weather
Destruction by volcanic materials
• Lava, rock fragments, volcanic bombs (ejected
molten lava blobs)
• Extreme temperatures of projectiles and lava
flow, destroying and killing.
• Inhaling hot gases and ash can also lead to
injury and death.
• With pyroclastic flow, speeds above 80km/hr
can be achieved, making it impossible to
• Collapse of a volcanic cone during eruption.
• Downward displacement of previous slide of
• Causes large scale damage to infrastructure
and loss of life.
• Settlements near the volcano may get wiped
• Ash particles and gases released disrupt
human activities over long distances.
• Some gases (Carbon monoxide, Sulphur
dioxide, etc) are harmful to humans
• Fine ash particles captured in the air endanger
planes and cause large monetary loss due to
grounding of flights.
Effects on weather
• Sulphur dioxide reacts with water vapour in
• The particles reflect the sun’s energy back into
• This leads to a cooling of surface temperatures
• Fall in global temperature might affect plant
and animal life.
Let’s attempt an exercise on what we
• 15 - 20 minutes,
• Complete all the questions in
Foolscap / space provided
• Good luck
• Caused by sudden release of stored
energy due to movements of crustal
• Occurs along faultlines as pressure builds
up stress and when the plates slip,
earthquakes are formed.
Key Earthquake Terms
• Seismic waves – energy that is released
• Focus – the point in the crustal plate
where the seismic energy originates.
• Epicentre – point above the Focus on
earth’s surface. Most of the energy
released travels along the surface of the
–subsequent smaller earthquakes that follow
after a major earthquake.
–Could continue to occur months after the
–Some aftershocks might be as powerful as
the original earthquake.
Depth of Focus
• The depth of focus affects the
impact felt on the surface.
• 2 key types
1. Deep-focus earthquakes
2. Shallow-focus earthquakes
Depth of focus
• Deep-focus earthquake
–70 to 700km below surface
–Smaller impact on land
–Most of seismic waves lose their
energy as they reach the surface.
Depth of focus
• Shallow-focus earthquake
–70km and above in the crust
–Greater impact on land
–Seismic waves reach surface
quickly and with more energy.
Measurement of earthquakes
• Richter scale
9?? Destruction impacts thousands of kilometers of land
Factors affecting earthquake damage
• Population Density
• Level of Preparedness
• Distance from epicentre
• Time of occurance
• Soil type
– High population density affects more people
– Tendency for high-rise buildings increases damage
– Higher literarcy rate in cities mean higher chance
of better preparedness.
• Higher chance of survival
• Better evacuation plans, trained rescue workers.
Level of preparedness
• Proper public training and social
awareness leads to less panic
• Repeated practice of emergency
exercise leads to familiarity of action
• Emergency preparedness kits raise
possibility of survival
Distance from the epicentre
• Seismic energy weakens as the
distance increases from the
• Locations further away from the
epicentre suffer less from the
Time of occurance
• Time of earthquake determines what
people are doing and whether they are
able to react.
• At night, people are asleep. There is less
time to react.
• In the day, survivors of an earthquake are
able to avoid subsequent accidents.
Type of soil
• Loose and unconsolidated (not packed
tightly) soil move more in times of an
• Impact on the buildings on the surface is
greater. Damage is often worse.
• Liquefaction – loose soil flowing like
• Danger of landslides after earthquakes
cause more harm.
• Tendency for earthquakes to occur
along crustal plate margins.
• Tendency for earthquakes to be
caused when subduction along
destructive plates or slipping of
Hazards of living in earthquake zones
• Disruption of services
• Loss of lives
• Loss of property
• Tsunami – an unusually large sea wave
• Formed by sudden movement of sea floor
• Possible causes
– Earthquakes at subduction zones
– Explosive underwater volcano eruption
– Underwater landslide
– Large coastal landslides
• As the displaced water moves, it gathers
strength and size.
• When it hits the coast, large destruction is
Disruption of services
• Loss of electricity, gas and water leads to
loss of essential services.
• Broken pipelines also raise the risk of
• Roads and railway destruction make it
harder to send aid.
• Earthquakes at timings where meals are
prepared raise risk of fires.
• Gas pipes and electric cables that are
broken lead to fire risk.
• Urban areas are densely populated,
hence larger fire risk.
• Shaking of earthquakes loosen soil.
• Along slopes and hills, original vegetation
may no longer be able to hold soil.
• Landslides and mudflows cause large
• Heavy rainfall after earthquakes raise the
risk of landslides.
Destruction of property and
Loss of lives
• Earthquakes destroy homes and buildings that
are not earthquake proof.
• Large amount of money needs to be spent to
rebuild the property.
• Urban areas with more infrastructure (roads,
subways) cause even more money to repair.