Transcript Natural Disasters2

Earthquakes: an
introduction
Hindu Mythology
Japanese Mythology
Imagine that you are an Australian
living hundreds and hundreds of
years ago. You have no scientific
understanding of the earth and how
earthquakes occur.
As an Australian, how would you
explain this phenomena?
Formation of the Earth
Continental Drift
Evidence
Other than the jigsaw pattern of the continents
there are two strong pieces of evidence to
support the theory of continental drift....
1. The rocks found in the lower/older layers of
mountain chains running across South Africa
and Argentina are the same, despite being
divided by the Atlantic Ocean.
2. Scientists have also found identical fossilised
remains of plants and animals on both Africa
and South America.
Plate Tectonics
Take out your Atlas!!
• On the blank map provided locate and
label all of the world’s tectonic plates,
and show the direction of movement of
each plate.
• Then locate and label the worlds
earthquake and volcano zones on the
map.
• Remember to use BOLTSS!
Plate Boundaries
• Plate boundaries exist on the borders of
tectonic plates.
• Tectonic plates are constantly moving, they
may crash into each other, slide past each
other or move apart.
• Where they interact, along their margins,
important geological processes take place,
such as the formation of mountain belts,
earthquakes, and volcanoes.
Earthquakes generally occur at plate
boundaries that:
• Are pulling apart
• Scrape past one another
• Slide under one another
•
•
Boundary of the Eurasian and North
American Continental Tectonic plates.
Richter Scale
Richter
Magnitudes
Description Earthquake effects
Frequency
Less than 2.0
Micro
Micro earthquakes, not felt.
8,000 per day
2.0-2.9
Minor
Generally not felt, but recorded.
1,000 per day
3.0-3.9
Minor
Felt, but rarely causes damage.
49,000 per year
4.0-4.9
Light
Noticeable shaking of indoor items, rattling noises.
Significant damage unlikely.
2,200 per year
5.0-5.9
Moderate
Can cause major damage to poorly constructed buildings
over small regions. At most slight damage to welldesigned buildings.
800 per year
6.0-6.9
Strong
Can be destructive in areas up to about 160 kilometres
(100 mi) across in populated areas.
120 per year
7.0-7.9
Major
Can cause serious damage over larger areas.
18 per year
8.0-8.9
Great
Can cause serious damage in areas several hundred miles
across.
1 per year
9.0-9.9
Great
Devastating in areas several thousand miles across
1 per 20 years
10.00+
Epic
Never recorded; see below for equivalent seismic energy
yield.
Rare (unknown)
Hazards
• Ground shaking
• Flooding: dams and levees can be ruptured by the
shaking
• Fire: Shaking can cause main gas lines and power
lines to break.
• Tsunami:(which we will be looking at later) caused
by earthquakes that occur under the sea.
• The majority of earthquake related deaths are
caused by collapse of buildings, although the other
hazards can be a serious issue as well.
2008 Sichuan Earthquake
Tremors
• Tremors from this earthquake
were not just felt in China, many
surrounding countries also felt
the affects of this massive
earthquake.
Using your Atlas, find Sichuan province (in
China)
• Locate the countries listed below
• Draw lines from Sichuan province to the
countries
• Using the map ‘scale’ find the country
that is furthest away from Sichuan
Province.
Hong Kong
Macao
Taiwan
Vietnam
Thailand
Mongolia
Bangladesh
Nepal
India
Pakistan