Download Earthquakes and volcanoes

Earthquakes and volcanoes
What are they?
1. energy
Seismicwaves
wavesreleased when plates move past each other
2. Richter
logarithmic
scalescale that measures earthquake magnitude
3. Continental
thick, granitecrust
plates that “float” on the mantle. They are less
dense than oceanic plates.
4. Tsunami
wave created by an underwater earthquake
5. Tectonic
where two
boundary
tectonic plates meet.
6. Convergent/destructive
where two plates meet, oceanic
margin plate is subducted below
continental to form volcanoes/earthquakes
7. Divergent/constructive
where two plates move apart
margin
creating a chain of volcanoes e.g.
Mid ocean trench
8. Evacuate
move people away from danger
9. Geothermal
energy formed
energy
by the heat of the earth
10. Pyroclastic
material erupted
flow from a volcano inc. ash, lava, gas and rocks
The following slide shows 4 plate
boundaries.
For each one
i. Name the boundary.
ii. Say what hazards it creates.
iii. Give an example of where it
happens.
B
A
a. collisional
b. Mountains and earthquakes
c. Himalayas
C
a. Conservative / tranform
b. earthquakes
c. California, Northridge
a. Constructive / divergent
b. volcanoes and (very occ) earthquakes
c. Iceland
D
a. Destructive, collisional
b. volcanoes and earthquakes
c. Andes, Mount St Helens, Montserrat
Minimising the effects
a.
b.
c.
d.
e.
f.
Emergency Drills – emergency services know exactly what to do so they
are organised [1] and can get people to safety quickly and efficiently
leading to less death [1]
Measuring gas emissions from vents – as magma rises gases like sulphur
are released [1] if emissions are increase it shows an eruption is imminent
and so people can be evacuated to safety [1]
Placing concrete blocks on the ground – concrete blocks can be placed in
the path of lava [1] this diverts the lava away from key buildings or
infrastructure [1] reducing damage and speeding up rebuilding
Counterweights in buildings – these reduce shaking of tall buildings [1]
this leads to less buildings collapsing [1] which reduces the death toll
(from falling building material) and cost of damage [1]
Monitoring animal behaviour – animals and birds often leave an area in
the hours before a quake [1] if animal behaviour is monitored this can give
us an early warning sign [1] and can lead to early evacuation [1]
Education – If people are aware of danger and how to react to it they can
be prepared [1] this means in an emergency they know where to go and
how to find out what is happening [1] reducing panic and confusion which
can slow rescue [1]
Causes of Hazards
a. Destructive boundary Caribbean and N and S American
Plates. Composite volcano which means its eruptions are
sudden and violent
b. Divergent boundary N. American Plate and Eurasian.
Shield volcano so gentle eruption. Glacier on top of
volcano melted forming floods and cooling lava to form
ash.
c. Conservative boundary – Caribbean and North American
Plates Epicentre was 25km from capital so the major city
and centre of emergency planning was destroyed. No
strict rules of construction so buildings weren’t strong
d. Conservative boundary N American and Pacific Plate.
15000 aftershocks which lead to damaged buildings
collapsing. Landslides blocked roads
Development
Compare the likely effects of an
earthquake in an MEDC and an LEDC.
Explain the likely differences.
Preparing for hazards
Suggest two ways that people can prepare for
or predict
a. Earthquakes
b. Volcanoes
For each one explain how this would be
effective