Predict, protect, prepare Objectives : To understand the need to predict, protect and prepare NT pg 30/31
Look at the picture carefully… what is happening here? Why is this being done?
http://uk.youtube.com/watch?v=3Rw0ayg85NM&feature=related http://uk.youtube.com/watch?v=lI1M8o0BHPc The photo shows how building designs are tested to see how they would stand up in earthquakes to help protect the occupants . The following clip shows an earthquake drill in California – it is called The Big Shakeout and is one way that people can prepare for an earthquake.
Putting laser beams across a fault to detect any small movement
Monitoring release of any radon gas
Monitoring water levels
Using seismometers – instruments that measure the movement of the ground
Graphing magnitude of earthquakes in specific places from the past
Watching for strange animal behaviour
Reducing the Effects of an Earthquake - protect
There are a number of strategies that can be used to reduce the impact of earthquakes. They all involve being fully prepared for the impact. 1. Install adequate warning systems. Warnings of the onset of earthquakes can be detected by organisations and governments. This involves the use of special sensing equipment. However, this alone will not be of much use without effective communication systems in place. Warning systems should be linked to government agencies, rescue and emergency services, and of course to the public.
Time is of the essence in the case of major disasters. Delay in support/action can result in further deaths. Local, national and international support services should know exactly what to do, and how they work together to produce a rapid, efficient and effective support system. 3. Provide information before 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 during an earthquake .
A building can never be made totally earthquake-proof. However, there are a number of ways that existing buildings can be made more resistant to earthquake damage.
New buildings can be designed to have a number of structural features which are more likely to provide resistance to the damaging effects of earthquakes. Structural damage could still occur, but the safety of the people inside the buildings is greatly enhanced by these special features.
Many of the injuries sustained by people are as a result of falling debris from buildings e.g. broken glass. Special attention to these potential hazards is a priority when designing earthquake-resistant buildings.
(i) Base isolation This works by essentially separating the building from the moving ground during an earthquake. The base will move with the ground, but the movement to the rest of the building is minimised by the provision of special features such as Teflon pads, enormous rollers, coiled springs
(ii) Diagonal bracing Shearing forces as distinct to push and pull forces, can cause tremendous damage to buildings. Diagonal bracing helps to minimise the effect of these shearing forces during an earthquake. (iii) Passive damping . Passive damping involves using a range of techniques. The main objective is to absorb the energy without allowing it to impact on the main structure of the building. Certain methods use materials which will deform easily, and therefore absorb the energy, without breaking. Other techniques include the use of large masses which are made to move out of phase with the movement caused by the earthquake. This tends to cancel out the disturbance, just like a trough of a wave in water meeting a crest of a wave will result in calm water (destructive interference in waves) ...