Importance of ozone layer and how to measure earthquake

 Why is the ozone layer important for the Earth?

About 18 to 30 miles above the surface of our earth, there is a layer of hot air. The warmth of this layer is caused because of the presence of ozone in it. Ozone is an allotrope of oxygen, that is, it has three atoms of oxygen in each of its molecules. Ozone absorbs rays coming from the sun. The hot ozone layer protects us from the most active ultraviolet rays and is essential for those living on Earth.

It has recently been found out by scientists that this life-saving ozone layer is being damaged due to some harmful atoms that are released from the earth’s surface. This is called the depletion of the ozone layer.

Ozone is a highly reactive gas. When chlorine atoms are produced by man-made chemicals like CFCs (chlorofluorocarbons) used in refrigeration, air-conditioning, plastic foams, aerosols, etc, and reach the ozone layer, the chlorine atoms break down the ozone atoms. The chlorine changes into chlorine monoxide and oxygen gas is formed.

This destruction of ozone molecules takes place at a faster rate near the poles. The phenomenon has been taking place for a long time but was discovered only in 1973 by American scientists Dr. Sherry Rowlands and Dr. Mario Molina.

Environmentalists and scientists all over the world are greatly concerned and are trying to save the vital ozone layer. Chemicals used in many modern gadgets that use ozone-depleting substances must be replaced by those not harmful. The dangerous hole created by the destruction of the ozone molecules in the atmosphere could spell doom for mankind.

How do measured earthquakes?

The crust of the earth is never absolutely quiet. Instruments called seismographs are used for detecting the vibrations on earth. These instruments are placed in different parts of the world to keep a record of vibrations every day, every year. The record sheets of two or more seismographs help seismologists find out where and of what intensity an earthquake has taken place.

Earthquake vibrations can be very strong, and as we know, can be very destructive. These vibrations may travel thousands of miles and so with the help of seismographs, an earthquake in China can be measured in a city in America. The earthquake vibrations consist of three or more kinds of wave motions that travel at different speeds through the rocky crust of the earth. They also move in different directions. The primary waves are around the earth’s surface. The damage we see on the earth’s surface is caused mostly by these long waves.

A seismograph has a delicately suspended weight that remains still when an earthquake shakes the other parts of the instrument. But the post which holds it moves with the disturbance and a chart attached to the post, underneath the weight also moves with it. As the chart moves, the movements are recorded on it by the weight. These record sheets can tell the time, intensity and even the direction of the waves of an earthquake.