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 However, there are Limitations in these methods!

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

Shock absorbers (base isolators) absorb tremors of earthquakes Cross-bracing Reinforce walls using two steel beams Shear walls (concrete walls with steel bars in them) to reduce rocking movements Earthquake Resistant Building

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 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 However, there are Limitations in these methods!