EARTHQUAKES
1. What are earthquakes?
Earthquakes are the sudden vibrations of the earth surface due to the collision of
plates. The rocks at the edges of these plates are ruptured into faults and the
sudden movement results in earthquakes.
2. What is the distribution of the world’s earthquakes?
(a) The Circum- Pacific belt – the Ring of Fire

Coincides with the young fold mountain belts on the east and west rims of the
Pacific Ocean

In zones of colliding plates and sliding plates

Accounts for over 68% of all earthquakes
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EARTHQUAKES
(b) The Mediterranean- North India belt

Coincides with the belt of young fold mountains stretching from the Himalayas
to the Alps and the Mediterranean region

In a zone of colliding plates

Experience 21% of all earthquakes
(c) Belts of minor earthquake activity, include

The mid- Atlantic belt, which coincides with the belt of volcanic islands and
oceanic ridges in the Atlantic Oceans, and is in a zone of diverging plates
beneath an ocean

The East African rift Valley, which is a zone of diverging plates beneath a
continent

Together account for 11% of all earthquakes.
3. Why earthquakes occur (cause of earthquakes)?
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EARTHQUAKES

Earthquakes are caused by the movement of the earth's tectonic plates.
Earthquakes occur where the earth's plates meet along plate boundaries.
For example as two plates move towards each other, one can be pushed
down under the other one into the mantle. If this plate gets stuck, it causes
a lot of pressure on surrounding rocks. When this pressure is released it
produces shock waves. These are called seismic waves. This is an
earthquake. The waves spread out from the point where the earthquake
started - the focus. More damage is done near the focus. The point on the
earth's surface directly above the focus is the epicentre.
4. Measuring Earthquakes

The magnitude (size) of an earthquake is measured using a seismometer.
This is a machine that measures movements in the earth's surface.
A seismometer

The Richter Scale (ranges from 0 to 9) measures earthquakes on a
logarithmic scale - this means that an earthquake of 6 is ten times more
powerful than one with a score of 5.
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EARTHQUAKES
5. Key terms

Fault- is a break in the rocks that make up the Earth’s crust, along which
rocks on either side have moved past each other.

Focus- the point in the earth’s crust where an earthquake originates

Richter Scale- A measure of earthquake intensity on seismographs

Epicenter- the point on the earth surface which receives the strongest
shock waves. It is directly above the focus.

Tremor- a shaking or vibrating movement of the earth

Seismic waves- are vibrations that travel through the Earth carrying the
energy released during earthquakes.
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EARTHQUAKES
Summary
EARTHQUAKE
World distribution
Measurement
of earthquake
magnitude
(size)
(a) The Circum- Pacific
belt – the Ring of Fire
Definition
(b) The Mediterranean
- North India belt
Sudden
vibrations of
the earth
surface due
to the
collision of
plates.
(c) Belts
of
minor
earthquake activity
SM SAYYIDINA OTHMAN, TUTONG
Cause of
earthquake
The
movement of
the earth's
tectonic
plates.
Using
seismometer
read in Richter
scale on a
seismograph
Key terms
1. Fault
2. Focus
3. Richter scale
4. Epicenter
5. Tremor
6. Seismic
wave
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EARTHQUAKES
IMPACT OF EARTHQUAKES AND TSUNAMI ON PEOPLE AND THE
ENVIRONMENT

Earthquakes can bring about great loss of life and damage to property. The
strong ground vibrations caused many buildings to collapse. Gas mains were
broken and immediately after earthquake, fires broke out, causing further
damage.

The table below shows the three types of effects of earthquake and tsunami
on people and the environment.
The primary effects
The secondary effects
The long-term effects
The shaking caused
These are effects that
These are things that
buildings to collapse,
happen later. They can
continue to be a
signs to fall off walls,
be fires caused by
problem for a long time.
windows to shatter,
broken gas pipes, or
They can be social,
furniture to fall over,
disease caused by
economic and
roads to crack,
dead bodies that aren’t
environmental. For
bridges to topple. All
buried, and also by
example in Kashmir, the
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EARTHQUAKES
these are primary
sewerage pipes bursting main long-term effects
effects. They caused
and contaminating
injury and death.
water supplies.
were:
In rural areas the crops
For example, in
For example, in
mostly survived and so
Kashmir, over 79000
Kashmir, the secondary
did the animals. So
people were killed, 100
effects included
farmers could continue
000 were injured, and
diseases (mainly
their jobs and the
3.3 million homes were
diarrhea) spread from
markets re-opened
destroyed by the
contaminated water
quickly. But in the urban
primary effects. There
supplies, and also
areas, lots of people
were large cracks in the
respiratory infections
lost their jobs as their
ground surface, and
like pneumonia. People
offices or shops were
landslides. The effects
also died of cold in the
damaged.
were so serious in
harsh winter, because
Kashmir because the
they only had thin tents
Electricity lines were
buildings in the towns
to live in.
brought down, so
and villages weren’t built
reconstruction was
very strongly.
made harder.
Schools were
damaged and students
lost their books.
3.3 million people lost
their homes and were
forced to live in
temporary shelters
until rebuilding could
start in the spring.
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EARTHQUAKES
Case Study: Japan Earthquake and Tsunami (11th March 2011)
The Japan earthquake occurred on the 11th March 2011. It was the largest
earthquake that they have had since records began. It was originally measured
as a 8.9 magnitude earthquake but this was later increased to a magnitude 9.0 as
more detailed readings came in from seismographs and other equipment.
The Japan earthquake was absolutely devastating. The earthquake itself, although
much bigger than usually seen in Japan, was prepared for extensively as
they receive many earthquakes every year. What was not adequately prepared for
was a tsunami of such scale. Many of the tsunami walls protecting coastline villages
were around 7 meters high, nowhere near big enough to stop the 10 meter high wall
of water (the height of a three storey building) that hit the coasts around 30 minutes
after the earthquake. This caused many thousands of Japan earthquake victims.
The Tsunami approaching Japan:
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EARTHQUAKES
 There have been over 11,000 Japan earthquake victims so far (as of
30/03/11), with over 17,000 still missing - many of which will also be dead.
The predicted death toll is 18,000 however this is likely to increase.
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EARTHQUAKES
 There are currently 244,000 refugees who are seeking shelter in the
Japanese earthquake relief camps. With many children still unable to find their
parents it is worried that the majority may be 'Japan earthquake orphans'. The
question therefore lies in what to do with them, foreigners looking to adopt
have been turned down as Japan wants to keep them in their home country
and culture. (Contrasting the Haiti orphan crisis)
 The tsunami caused a near catastrophic meltdown of a nuclear power plant
which exploded multiple times and released radioactive material into the air
causing dangerous levels in foodstuffs grown within tens of kilometers.
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EARTHQUAKES
 The water supply in many areas is unsafe to drink due to radioactivity and
some of the plant workers risking their lives to cool the plant's core were
exposed to massive overdoses and are now in hospital. Japan earthquake
relief organizations have been handing out water bottles to survivors.
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EARTHQUAKES
 Boats were dragged inland and left deserted, houses were ripped from their
foundations and scattered among the remains of others, some even stacked
on top of each other.
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EARTHQUAKES
Summary
Impact of earthquakes and tsunami on people and the environment
 Death and injuries
 Homeless
 Collapse of building
 Windows shatter
 Roads crack
 Bridges topple
 Fractured gas pipes and water mains
 Fire caused by broken gas pipes
 Disease spreads by dead bodies and contaminated water
 Landslides
 Tidal waves
 Loss of jobs
 Cut off of electricity
 Rebuilding of Schools
 Rebuilding of home
 Loss of family members
 Air Pollution
 Land Pollution
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EARTHQUAKES
STRATEGIES TO REDUCE THE IMPACT OF EARTHQUAKE
There are a number of strategies that can be used to reduce the impact of
earthquakes.
 Install adequate warning systems.
The use of special sensing equipment and devices with effective
communication systems which are linked to government agencies, rescue
and emergency services, and the public should be put in place to warn
people on earthquake occurrences.
- Seismograph
- A seismograph is an example of a device and instrument that detect the
earth's movement and vibrations.
- A seismograph consists of a ground motion detection sensor called a
seismometer, coupled with a recording system.
Seismograph
- Seismometers help in monitoring the frequency of the Earth's vibrations
and detect the development of tsunami. The monitoring and predictions
made by seismometer provide crucial information so that people living in
affected areas can be warned and evacuated before a disaster strike
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EARTHQUAKES
Graph obtained from seismograph
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EARTHQUAKES
Example:
In December 2004, a massive earthquake occurred off the coast of Sumatra, killing
tens of thousands of people living in countries where there were no tsunami warning
systems. The government of Indonesia is now developing a warning system to
prevent a similar tragedy. Japan and the western United States have well-developed
tsunami warning systems, should a quake occur offshore of those areas.
 Construct Earthquake -Resistant Buildings
- Earthquake resistant buildings can be constructed in areas with frequent
earthquakes.
Earthquake resistant house
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EARTHQUAKES
'Quake proof' Houses
- The earthquake resistant buildings are built with deep foundations with
rubber shock absorbers and concrete reinforced with steel. They are designed
to twist, sway and have sprinkler systems and gas cut off valves.
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EARTHQUAKES
Earthquake resistant building
- In some many earthquake resistant buildings, technologies and structural
modifications are used to protect buildings from damaging earthquake effects.
- Technologies such as Base Isolation Devices, Seismic Isolation systems,
Seismic Dampers and Energy Dissipation Device are used.
- The base isolation is to detach (isolate) the building from the ground in such a
way that earthquake motions are not transmitted up through the building or at
least greatly reduced.
- Seismic dampers are special devices introduced in the building to absorb
the energy provided by the ground motion to the building (much like the way
shock absorbers in motor vehicles absorb the impacts due to undulations of
the road).
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EARTHQUAKES
Building structures designed to withstand earthquakes
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EARTHQUAKES
 Educate and provide information to the public before, during and after
the earthquake strikes.
 This can involve the use of radio, TV and newspapers. Everyone should know
(i) What precautions they need to take for the own safety and for the safety
of others.
(ii) How to secure their home and belongings against damage.
(iii) What to do before, during and after an earthquake.
 Use of Technology to prevent Fire Hazards
Electronic systems can be installed to cut off electricity and gas supplies
automatically during an earthquake. This would minimize the danger of fire
caused by 'live' wires or bursting of gas pipes.
 Earthquakes drills.
- These are held to practice what to do in the event of an earthquake taking
place such as the one held in Japan on Sept 1st every year.
- Earthquake drills should be carried out in schools, offices and homes on a
regular basis
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EARTHQUAKES
 Have a unified plan of action.
Time is important in the case of major disasters. Delay in support and action
can result in many deaths. Local, national and international support services
should know exactly what to do, and how to work together to produce a rapid,
efficient and effective support system, that is, by forming Community
Emergency Response Teams (CERT)
-
The Community Emergency Response Team (CERT) Program educates
people about disaster preparedness for hazards that may impact their area
and trains them in basic disaster response skills, such as fire safety, light
search and rescue, team organization, and disaster medical operations.
-
Using the training learned in the classroom and during exercises, CERT
members can assist others in their neighborhood or workplace following an
event when professional responders are not immediately available to help.
-
CERT members also are encouraged to support emergency response
agencies by taking a more active role in emergency preparedness projects in
their community.
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EARTHQUAKES
 Emergency plans.
These are drawn up, supplies such a bottled water, medicines and tinned
food are stockpiles by individuals or local areas.
 Provide rapid and efficient support system after an earthquake.
- Medical assistance, food, medicine and accommodation are needed fast
after an earthquake. These supplies should come as quickly as possible
which can reduce the number of deaths.
- Heavy duty machines are also needed to reduce the time taken to achieve
rescues.
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EARTHQUAKES
Summary
Install adequate
warning systems
Build earthquake
resistant buildings
Emergency
plans
Emergency drills
STRATEGIES TO REDUCE
THE IMPACT OF EARTHQUAKES
Educate and
inform public on
earthquakes
Technologies to
prevent fire hazards
Efficient and rapid
support system
Unified plan of
actions
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EARTHQUAKES
WHY STRATEGIES USED TO REDUCE THE IMPACT OF
EARTHQUAKES MAY BE LESS EFFECTIVE IN LEDCS THAN MEDCS
The following differences between LEDC and MEDC need to be considered:
MEDCS
1. Health
care
Have the medical resources and
money to quickly get appropriate aid
to areas after a natural disaster.
LEDCS
Rely on aid from overseas as their
health
system,
inadequate.
This
which
overseas
is
aid
takes time to arrive.
Such as Japan and New Zealand,
there
are
well
thought
out
emergency procedures:The
departments Do not have these emergency
government
responsible
for
and plans, and so far more damage
managing
coordinating emergency responses, can be done before the emergency
2.
and for educating the public about services reach the area.
Emergency natural hazards.
The remoteness of some areas
services
and
Education
In Japan regular earthquake drills made it difficult for authorities to
are held in schools and places of monitor and to educate the people.
work, and every year a full-scale
practise
for
emergency
armed
forces
and
services
is
held.
Emergency
services
actually
practice through simulations, so they
know exactly what they should do if
disaster strikes.
3. Building
technology
Japan
and
the
United
States Don't tend to have the technology
developing buildings that have more available or money to pay for it,
chance of resisting an earthquake:-
SM SAYYIDINA OTHMAN, TUTONG
and so often their buildings are
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EARTHQUAKES
Most houses in San Francisco are very susceptible to earthquakes.
made of wood, to make them more
flexible and allow them to move with
Communication systems may be
underdeveloped, so the population
the quake.
may not be well educated about
Larger skyscrapers are built with
flexible
foundations,
(shock
absorbers) which allow them to sway
during a quake, rather than being
rigid and falling down.
what to do in the event of an
earthquake.
Construction standards tend to be
poor in LEDCs. Homes and other
buildings
may
suffer
serious
damage when a disaster occurs.
Many countries in areas prone to
natural hazards have building codes Buildings collapsing can cause
to say where they can and cannot high death tolls.
build, and how high the buildings
In contrast to the Kobe earthquake
can be.
that killed 5500, an earthquake of a
In 1995, the Kobe earthquake hit in slightly smaller intensity hit Gujarat
in India in 2001. It killed
Japan. Measuring 7.2 on the Richter
scale it had the potential to cause 20 000 people.
massive
damage
buildings,
but
to
vulnerable
because
many
buildings were designed to withstand
earthquakes, only 5500 people were
killed.
Have
4.
Scientific
prediction
scientists
to
monitor
and No investment in research and
planted
a
huge
number
of development.
Therefore, no
seismographs in the ground to try to qualified scientist and limited or no
detect even the faintest of tremors.
number of seismograph to detect
tremors.
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EARTHQUAKES
Allows the sufficient time to evacuate Evacuation and other emergency
people from the danger area.
plans can be difficult to put into
action due to limited funds and
resources
No time to evacuate people.
Able to recover quickly from a Because LEDC's often have to rely
natural disaster, due to having the on aid from overseas, this quick
investment and technology needed recovery is often impossible for
to return the area to as good as new them.
as soon as possible.
Clearing up can be difficult. There
They can afford to allocate funds to
'just in case' measures. They keep
emergency stocks of
medicines,
tents, blankets, food, water, and
communications equipment. It's kept
5.
Recovery
ready
for
updated.
use
and
MEDC's
constantly
have
the
resources close at hand and can be
sending them out within hours.
may not be enough money to
rebuild homes quickly and safely.
Many people could be forced to
live
in
emergency housing
or
refugee camps.
Many LEDC's struggle to provide
these facilities for normal use let
alone
keep
a
spare
set
of
everything in case of disasters.
The
speed
with
which
these
resources reach an area is critical
to reducing deaths.
By contrast, LEDC's often have to
ask
for
help,
and
mobilising
international aid can take days. As
a result people die from diseases
as they have no fresh supplies.
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EARTHQUAKES
Summary
WHY STRATEGIES USED TO REDUCE THE IMPACT OF EARTHQUAKES MAY BE LESS
EFFECTIVE IN LEDCS THAN MEDCS?
Because the following factors are different in the LEDCS and MEDCS
Emergency
services and
education
Health care
SM SAYYIDINA OTHMAN, TUTONG
Scientific
prediction
Building
technology
Recovery
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