Predicting Earthquake and Protection- Biology Guide for Class 8
Information about Predicting Earthquake and Protection
Title | Predicting Earthquake and Protection |
Class | Class 8 |
Subject | Class 8 Biology |
Topics Covered |
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The Focus
- Scientists (Geologists) call the point of origin of the earthquake, i.e. the point at which tension is released, as its focus.
- Since this is often deep below the surface of earth, and difficult to map, its location is specified by the point (place), on the surface of earth, directly above the focus. This point, on the surface of earth, is known as the epicenter of the earthquake.
- The shock/seismic waves move outwards from the epicenter.
- The maximum damage, due to an earthquake, usually occurs closest to its epicenter.
- The strength/intensity of the earthquake decreases away from the epicenter.
- The whole phenomenon may last for just a few seconds.
Predicting an Earthquake
We now know about the cause of an earthquake. However, to predict, when and where, the next earthquake might occur, is a very difficult task. Attempts at predicting, when and where earthquakes will occur, have met with some success in recent years.
- Geologists use instruments, such as seismometers, to find out the source of seismic waves.
- They are also investagating other potential clues: like tilting/ bulging of buildings and changes in the earth's magnetic field.
Local people adopt some common earthquake prediction methods by observing the behaviour of birds and animals. When fishes in the pond get agitated, the sky becomes silent and snakes come to the surface, an earthquake may occur.
Measuring an Earthquake
We can realise that the destruction/damage caused by an earthquake depends on many factors. One major factor is its intensity (power).
Geologists usually express the intensity (power) of an earthquake in terms of a 'magnitude' on a scale, known as the Richter Scale. The Richter scale, named after Dr. Charles F. Richter, is the scale used most often for measuring the strength of an earthquake; it does so in terms of the amplitude of its seismic/shock waves.
- This scale is not a simple linear scale.
- On this scale, an increase of two in the magnitude, means 100 times more destructive energy. Similarly, an increase of three in the magnitude, means 1000 times more destructive energy; and so on.
Richter Scale
|
Magnitude |
Effect of quake |
|
2.5 |
Generally not felt, but recorded on seismometer |
|
3.5 |
Can e felt by many people |
|
4.5 |
Some local damage (cracks in buildings and dams may occur) |
|
6.0 |
A destructive quake |
|
7.0 |
A major destructive quake |
|
8.0 and above |
A highly destructive quake, capable of destroying an entire population |
Protection against Earthquakes
The earthquakes strike suddenly and violently, without warning, at any time of the day or night. If an earthquake occurs in a populated area, it can cause injuries and death and property loss. It is, therefore, important that we identify the potential hazards before hand and take necessary precautions to protect overselves as best as we can.
People living in seismic zones, where the earthquakes are more likely to occur, have to be specially trained, and equipped, for saving themselves.
The following measures/precautions can help in minimising the damages due to earthquakes.
- All the buildings in seismic zones need be designed so that they can withstand major tremors. It is advisable to make the structure simple so that it is 'Quake Safe'.
- Since some buildings may catch fire (due to an earthquake), it is necessary that all the buildings (specially the tall ones) have their fire fighting equipment in order.
- Safer places, indoors, as well as outdoors, must be clearly identified.
- An emergency communication and exit plan should be made available.
- Disaster management supplies (like flashlights, first aid box, etc.) should be available 'on hand'.
Safety Precautions during Earthquake
For a person present inside a building:
- Take shelter under a table and stay there till the shaking stops.
- Stay away from tall and heavy objects that may fall on you.
- Do not get up if you are in a bed. Protect your head with pillows.
- Stay indoor until shaking stops and it is safe to move outside. Most of injuries occur when people, inside the building, attempt to move to a different location within the building, or try to run out of the building.
For a person caught outside in the open:
- Find a clear spot, away from buildings, trees, bridges and overhead power lines. Drop to the ground.
- Do not come out if sitting in a moving vehicle. Drive slowly to a clear spot and stay inside. Come out only when the tremors stop.
Safety Precautions after the Earthquake
- Stay calm for a while. Expect 'after shocks'. These shocks can cause additional damage.
- Beware of possible tsunami if you live in coastal area.
- Carefully inspect utilities/supplies.
- Use telephones only in emergency.
- Stay away from damaged areas.
- Help the injured ones.
The Central Building Research Institute Roorkee, has developed some 'know how' to make quake proof houses.