Methods to Reduce the
Impacts of Volcanoes & EQ’s
In this lesson, you will understand that:
• Various Methods can be used to Reduce the Impacts
of Earthquakes & Volcanoes
1. Planning the Location of Infrastructure
2. Designing Earthquake Resistant Infrastructure
3. Strengthening Existing Infrastructure
4. Education
5. Earthquake & Volcano Monitoring and Warning
Systems
So what’s the ‘Problem’?
• Solution/Method/Measure/Adaptation:
1. Planning the location of infrastructure
–Build new infrastructure away from earthquake
prone areas to reduce economical damage and
lower number of deaths caused by earthquakes
–Authorities can implement guidelines on the
location of new infrastructure and set limits on the
heights of buildings
Buildings are not too tall in
earthquake-prone Japan!
Vs skyscrapers in
NYC
• Example:
• In USA, authorities use earthquake risk maps to
control land use so as to minimise damage that may
be caused by earthquakes
• Limitation:
• The control of land use is difficult in cities of LEDC’s
where there is high rural-urban migration and the
country lacks resources to improve the situation
• Poverty causes such migrants to construct their
houses illegally on earthquake-prone zones, where
they may suffer devastating effects of earthquakes
Imagine the damage that earthquakes can
cause to these slums in Mumbai!
What is so special
about this building
in Japan?
• Solution/Method/Measure/Adaptation:
• 2. Designing Earthquake-Resistant Infrastructure
–New infrastructure can be specially designed to
withstand strong tremors by making use of the
latest technology
Earthquake Resistant Building
Cross-bracing
Reinforce walls
using two steel
beams
Shock absorbers
(base isolators)
absorb tremors of
earthquakes
Shear walls
(concrete walls
with steel bars
in them) to
reduce rocking
movements
The Transamerica
Pyramid in San
Francisco cost S$75
million to build!
Triangles & Wide
bases
• Limitation:
• People living in LDCs cannot afford to construct such
expensive earthquake resistant infrastructure
Problem:
There are still more than 1.8 million older
buildings that cannot withstand earthquake
tremors in Tokyo alone!
• Solution/Method/Measure/Adaptation:
• 3. Strengthening Existing Infrastructure
–New infrastructure can be specially designed to
withstand strong tremors and reduce damage from
earthquakes by making use of technology
–we call this retrofitting
• Example:
• Existing infrastructure can be
reinforced by wrapping steel
frames around the pillars of
buildings and bridges, or by
placing steel rods in existing
structures
• Example:
• Fireproof materials and automatic shut-off valves
can be installed into gas pipes and electricity
supplies to minimise the risk of fires in the event of
an earthquake
• The effectiveness of seismic retrofitting is limited as
the strengthened infrastructure may not be as strong
as new earthquake resistant infrastructure
• Example of Limitation:
• During the 1994 EQ in USA, many buildings and
highways that had been strengthened with steel
frames were badly damaged
• However, new earthquake-resistant buildings in the
same area remained undamaged
Watch Quakewrap!
• Solution/Method/Measure/Adaptation:
• 4. Education on Emergency Procedure
–Earthquake drills are conducted regularly in many
earthquake-prone countries to educate and
familiarise people on what to do in the event of an
earthquake
–Governments of earthquake-prone countries also
use posters and signs to warn people about areas
that are prone to the effects of earthquakes e.g.
coastal areas where tsunamis can occur
Drills are voluntary!
• Limitation:
• People tend to be complacent and may not see the
importance of earthquake education especially if
earthquakes have not happened in the region for a
long time
• Solution/Method/Measure/Adaptation:
• 5. Earthquake Monitoring and Warning Systems
–Earthquake-prone areas should invest in
seismometers and computers that can monitor
tremors of the Earth or change in water levels
–Authorities will then inform residents through sirens
or public broadcasts of impending danger and begin
mass evacuation
• Example:
• In Haicheng, China, scientists identified changes in
the ground level and increase in small tremors which
are signs of an impending earthquake
• Authorities were informed and people were warned
to evacuate the city
• 90 000 people were saved from the magnitude 7.3
earthquake that destroyed 90% of the city’s
infrastructure
Tsunami Monitoring
and Warning System
• Limitation:
• The effectiveness of an earthquake monitoring and
warning system is limited
• Authorities may choose to ignore warnings to avoid
disruptions to business and tourism as
• Predictions of scientists may not always be accurate
and turn out to be false alarms
How to predict Volcanoes?
•
Mt St Helens gave off pre-tremors. These were
measured by seismographs and indicated that
magma was moving inside the volcano
Vulcanologists tested ash samples after each mini release of steam, and
checked for sulphur dioxide levels – a rise would indicate that magma was
on the move. Volcanic gas collections were taken via aeroplane.
Mt St Helen’s was growing...
• A developing bulge was
detected by
tiltmeters on the
volcano’s north side. The
bulge, developed as
magma pushed up within
the volcano. Angle and
slope-distance
measurements indicated
it was growing at a rate
of up to 1.5m
Also...
•
Satellite images can
record the warming of the
ground surface as the
magma edges towards
the breakthough point.
This satellite image of
Mount St Helens was
taken about one month
before it erupted. The
infra-red image shows the
hottest areas of the
volcano in red and the
coolest in black.
In this lesson, you have understood that:
• Various Methods can be used to Reduce the Impacts
of Earthquakes
1. Planning the Location of Infrastructure
2. Designing Earthquake Resistant Infrastructure
3. Strengthening Existing Infrastructure
4. Education
5. Earthquake Monitoring and Warning Systems