Since yesterday (25th april) #earthquakes are experienced at Cuttack,Odisha; my home town. Though Odisha faces Cyclone and Flood like natural calamities every year or every other year, but earthquakes are rare. But since yesterday Odisha have witnessed several quakes some are major and some are minor.
Why Earthquakes happen?
Yesterday few school students for the first time (perhaps) experienced earthquake so they asked me "Uncle What is earthquake? why it happens? and how it happens?" Looking at their tender age and curiosity I described them as follows.
During break you play in the school right? "Yes uncle we do". Do you run on the corridor? "Yes uncle". Good, now tell me do you hit during running? "Yes". So when you hit someone while running what happens? I asked, "It hurts" they replied. Similarly the surface of earth is moving constantly, as you have studied in your science book core of earth is not solid, it is molten rocks. and the upper surface which is cooler is harder and it floats on the molten rock. When these floating harder rock hits other floating rock earthquake happens. Like you also shake when you hit your friend, earth's surface also shakes, this is known as earthquake.
In Technical terms, earth surface is divided into several tectonic plates. These tectonic plates are floating on the molten core of the earth. These tectonic plated are in constant movement. So they press with each other. Due to this pressure sometimes they break or one plate dives in and other plate goes up. Himalayan mountain is created by this tectonic plate movement. Our Indian plate hits Eurasian plate and dives under it, and Himalayas is created.
[Source of the image is "http://www.tectonics.caltech.edu/"]
Is there any way to predict
No. There are several attempts made to predict earthquake but there is no way it can be predicted. But there are precursors to earthquake.
- Soil resistivity change
- change in radioactivity profile of a place
- sudden change in water table
- unusual lights and sound
There are 2 scales but the most common now a days is Richter scale and another scale is Rosi forel scale. The former is scientific based on mathematical formula, the later is a visual scale based upon experience.
The instrument which measures earthquake magnitude is known as seismometer.
Seismometer operates on the principle of Inertia of rest. a simple seismometer is a simple pendulum. A simple seismometer can be made by attaching a pencil to a pendulum.
"Earthquake doesn't kill, structure collapse kills". So there is only precautions we can take. such as
- Earthquake resistant construction practice
- If earthquake happens then quickly get out to open sky
- If getting out is not possible then go to a corner of the room and hold a pillow or some thing over head
- If that is also not possible then hide yourself under a strong table with a pillow or something.