NCERT Class 7 Geography Chapter 3: Our Changing Earth Completes Notes Part 2

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Our Changing Earth


Image of Earthquakes

Image of Earthquakes

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Now earthquakes when we classified earthquakes we can understand the various waves that coming in three basic classifications: P waves, S waves and L waves. P waves are longitudinal waves, s waves are transverse waves and L waves are surface waves. Which could be felt over the surface of the earth. So what happens during the process of volcano, earthquake is you have unrest that happens on surface and that unrest is governed by a kind of focus point which is below the surface of earth.

Now this is focus point which is below the surfaces of the earth and this is I can say origin of earthquake. Now the perpendicular line where it meets straight line on to the surface would be epicenter or the main area of earthquake spreads and then you would have seismic waves. That could be felt around the epicenter. So epicenter would form center of the seismic waves. Seismic waves means the earthquake waves so seismicity is another terms that we use for earthquake and this seismic waves as the move away from the epicenter they become weak so the waves which are closest to the epicenter would be the strongest and as you move away from the epicenter the effect of earthquake would gradually and slowly declaim.

Now Richter scale is the scale throw which you major intensity of earthquake. It’s a kind of logarithmic scale and in intensity increases 10 times from say 5 if I say intensity of 5 at Richter scale and then of 6. That means this intensity of 6 is nearly 10 times when I say the intensity at 5. So this is how we understand the Richter scale and now some important tips for preparedness.

Earthquake Preparedness

  • Measured by Richter Scale

  • Safe Spot – Under a kitchen counter, table or desk, against an inside corner or wall.

  • Stay Away from – Fire places, areas around chimneys, windows that shatter including mirrors and picture frames.

  • Be Prepared – Spread awareness amongst your friends and family members and face any disaster confidently.

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    Earthquakes - Causes, Distribution, Impact & 4 Types of Waves

There are certain safe spots that you must recognize so whenever you are standing against a corner of the wall the inside moves region is the safest because when there would be a kind of wall that is falling it would be towards the outer side so if you are inside a room inside a closed space the safest area is standing closest to the corner or closest to the wall because that would be the safest region under the kitchen counter, table or desk would be another certain safe spaces.

You should always stay away from fires away from ignitable regions and spread awareness among the family members. so these are the some of the important highlight that we cover for earthquakes now next is difference between weathering and Erosion.