An earthquake is caused by a sudden release of energy stored in the Earth's crust along a fault line. The focus is the point of energy release within the crust, while the epicenter is the point directly above the focus on the surface. When plate movements cause built-up stress to exceed rocks' limits, the stored energy is released as seismic waves, causing the ground to vibrate and potentially damage infrastructure through collapse or landslides. Earthquakes can also indirectly cause fires, tsunamis, and other hazards.

1. An earthquake is a vibration or tremor of the Earth’s surface caused by the sudden release of energy
stored in the crust. The focus is the point of release of energy within the Earth’s crust. The epicentre is the
point on the Earth’s surface that lies directly above the focus.
Formation of earthquake
When (plate name) converge/diverge/slide past (plate name), the plate movements are not smooth.
A lot of pressure is built up because of the tremendous amount of friction. As the rocks are forced
to bend, large amounts of energy are stored in the rocks. When the stress become too immense to
be held by the rocks, they jerk free into new positions along a fault line. The stored energy is
released in the form of seismic waves which causes the ground to vibrate.
Factors affecting STRENGTH of earthquake Description
Shockwaves are felt more strongly near the
Distance from epicentre
epicentre as the waves are not weakened much.
Shallow focus leads to a stronger earthquake as
Depth of focus
vibrations are not weakened as they travel upward.
Type of hazard Earthquake hazard Description
- Urban features (eg. flyovers,
bridges, buildings) may not be
able to withstand vibrations of
earthquake.
Collapse of infrastructure - Foundations may be weakened
and aftershocks may collapse
entire structure.
- People are trapped under rubble
Direct and they may die.
- Earthquake causes ground to
shake, loosening soil causing it to
slide down a slope, barying
people and buildings along the
Landslides way.
- Worsened by deforestation,
without roots, nothing to bind
soil together.
- Damaged wires, overturned
stoves, broken gas pipes will
cause sparks to light a fuel source
Indirect Fires which will cause fires.
- People may be burnt, buildings
may collapse when burnt badly
leading to high loss of lives.

2. - Earthquakes causes displace-
ment of seabed which displaces
water and causes a tall wave to
crash onto shore.
- Floods may wash away people
and they drown. Buildings are
severely damaged by
Indirect Tsunamis floodwaters.
- Formation of tusnami: SAME
AS FORMATION OF SWASH.
- 2004 Indian Ocean Tsunami
was triggered by an undersea
earthquake where >250k lives
lost.
Impacts of earthquake Elaboration
- Earthquakes can cause loss of live through
abovementioned hazards.
Loss of lives
- Further worsened if emergency efforts is slow to
arrive. Aftershocks may also cause as much loss of
lives as the main earthquake.
- Destruction of infrastructure inconveniences
businesses located in affected area because
consumers or products cannot get to shop.
- Tourism is affected as rubble in unappealing and
Negative economic consequences no tourists would want to visit the earthquake-hit
country, fearing another one will occur.
- Cost of reconstruction and repairing is high
especially in well-developed urban areas (eg. cost
of reparations of 1995 Kobe EQ: S$100 bil)
- Survivors would live in overcrowded makeshift
shelters that lack in proper sanitation facilities and
clean drinking water.
Spread of diseases
- Spread of water-borne diseases occurs,
unremoved dead bodies and sewage water pollute
water and reduces amount of clean drinking water.

3. - Coupled with image of disasters, loss of lives,
Trauma monetary and housing worries leave victims
paranoid and scared of the future.
- People with coastal jobs (eg. owners of beach
Disruption of jobs resorts, fishermen) would temporarily have no jobs,
creating worries about their livelihood.
Factor influencing extent of damage Description Example
- The stronger the earthquake, the - In the 2010 San Francisco EQ
more powerful the seismic waves with magnitude of 4.2, there was
and the more destruction occurs hardly any casualties. In the 2010
Magnitude of earthquake
at the earthquake zone. Haiti EQ with magnitude of 7.0,
there were 200 000 deaths
reported.
- Shockwaves are felt more - In the 1993 Maharashtra EQ,
strongly near the epicentre as the Killari which was 12km from
Distance from epicentre waves are not weakened much. epicentre had far more deaths
than Gulbarga which was 84 km
from the epicentre.
- A place with a sparse - In the 1964 Anchorage EQ, a
population and few buildings will 9.2 magnitude earthquake killed
Population density
have few deaths as there is not only 115 people because Anchor-
many collapses. age had a sparse population then.
- Places with soft soil experience - In the 1985 Mexico City EQ,
stronger shock waves than places more damage was seen in Mexico
with hard soil because soft soil City (built on soft soil) than
Geology
amplifies the shock waves. Acapulco (built on hard soil)
even though Acapulco was
nearer the epicentre.
- In places where people are - In Japan, frequent drills are held
more prepared and buildings are to educate the public hence it
Level of preparedness more resistant, there would be does not have much injuries or
less deaths and less building casualties during its frequent
collapse. earthquakes.

4. Adaptation Description + - Example
- If possible, infra- - Increases - Illegal slums - In USA, earth-
structure should be distance from built by the poor quake risk maps
as far away from epicentre hence can inhibit efforts have been drawn
Planning the
earthquake prone weaker seismic to relocate, poor to draw up
location of
zone. Estimation waves reach the cannot move into building guidelines
infrastructure
of level of risk of place, may be so proper houses. to ensure minim-
ground failure little to cause no um damage during
advised. damage. earthquakes.
- New infrastru- - More resistant - Very expensive - In California,
cture can be built to earthquake to build and USA, the
to withstand tremors preventing maintain. Transamerica
strong tremors collapse and loss Pyramid at S$75
- Historical
caused by earth- of lives. mil to build.
Designing new buildings are not
quakes. Make use
infrastructure conserved as these
of latest tech- - In Tokyo alone,
buildings are
nology (eg. steel there are more
required to be
bars, shock absor- than 1.8 mil old
demolished.
bers) to dissipate buildings.
energy
- Steel frames, - Historical - Not as resistant - In the 1994
rods wrapped buildings are as compared to Northridge EQ,
around pillars of conserved as these new buildings buildings and
buildings and buildings hold flyovers strengthe-
Strengthening bridges. Fireproof significance to the ned with steel
existing materials and auto country. frames were dama-
infrastructure shut-off valves can ged despite the
be installed to - Cheaper than new earthquake-
reduce chance of demolishing and resistant buildings
fire. rebuilding. remain-ing
unchanged.
- Regular drills to - People are well - Complacency is - Research shows
familiarise with prepared and they an issue as people that people in
warning signals, know what to do in do not take this Tokyo are more
Education posters to educate an earthquake. drills seriously. complacent as a
public major earthquake
has not happened
recently.
- Sophisticated - Gives time for - Authorities and - In the 1975
instruments (eg. evacuation if businesses ignore Haicheng EQ, 90
Earthquake seismometers, detected early, warnings to 000 people were
monitoring and underwater tsun- reduces loss of prevent loss of evacuated as
warning systems ami sensors) warn lives. business and scientist could
people to evacuate interruption to detect ground
early when detect- services. changes early.
ed.