Be Safe, Life Comes First #1 – An Earthquake

Nature. Nature is a WONDEFUL thing gold gave us, but sometime when its angry it rages a lot. We can not predict natural calamity. but, we can be safe from them with just some small thing. What ever happened in Nepal will never be forgotten. 

An earthquake is the shaking of the earth caused by pieces of the crust of the Earth that suddenly shift. The crust, the thin outer layer, is mostly cold and brittle rock compared to the hot rock deeper inside. This crust is full of large and small cracks called faults. Although these faults can be hundreds of miles long, usually you cannot see the cracks because they are buried deep under­ground and because the pieces of crust are compressed together very tightly

The powerful forces that compress these crustal pieces also cause them to move very slowly. When two pieces that are next to each other get pushed in different directions, they will stick together for a long time (many years), but eventually the forces pushing on them will force them to break apart and move. This sud­den shift in the rock shakes all of the rock around it.

Earthquakes occur because of a sudden release of stored energy. This energy has built up over long periods of time as a result of tectonic forces within the earth.

Most earthquakes take place along faults in the upper 25 miles of the earth’s surface when one side rapidly moves relative to the other side of the fault. This sudden motion causes shock waves (seismic waves) to radiate from their point of origin called the focus and travel through the earth.

It is these seismic waves thasst can produce ground motion which people call an earthquake. Each year there are thousands of earthquakes that can be felt by people and over one million that are strong enough to be recorded by instruments.

Strong seismic waves can cause great local damage and they can travel large distances. But even weaker seismic waves can travel far and can be detected by sensitive scientific instruments called seismographs.

Different types of Seismic Waves:

When you drop a rock into a calm lake, you see (water) waves traveling outward in all directions through the water. When you pop a balloon, sound waves travel outward in all directions through the air. When rock deep inside the earth sud­denly moves, it sends seismic waves outward in all directions through the earth.

Moving Plates:

Seismic waves start where a large section of rock suddenly shifts. This rock movement creates at least three types of waves: Primary (P) waves: Pressure waves caused when rock is pushed or pulled forward or back­ward.

Primary waves, the fastest wave sent out by an earthquake; travel down into the earth rather than along the surface. (Remember: P waves – primary, pressure, and push-and-pull). Secondary (S) waves: Shear waves caused when rock is shaken or whipped from side-to-side, like the wavy motion of a slithery snake.

Secondary waves, the second-fastest wave sent out by an earthquake; travel down into the earth rather than along the surface. (Remember: S waves – sec­ond, shear, side-to-side) Surface (L) waves: Up-and-down (rolling) or side-to- side motion of the earth surface.

Surface waves, the slowest earthquake waves, travel along the surface of the earth rather than down into the earth. Although they are the slowest of all earthquake waves, L waves usually cause more dam­age to society than P or S waves.

L waves were named after a geologist who studied them. (Remember: L waves are always the last to arrive. Every earthquake creates these three kinds of waves. P and S travel downward into the earth, and L waves travel along the top of the crust. Geologists have developed several ways of measuring the size of an earthquake.

Two of the most common ways are:

1. The Richter scale which measures the energy released in an earthquake by measuring the size of the seismic waves.

2. The Mercall scale which measure the result of an earthquake, such as the shaking and damages that actually feel and see.

Facts about Earthquakes:

1. Earthquakes are caused by the movement of large earth plates.

2. Plate tectonics is the recycling process (Uplifting, eroding and sinking) of the earth’s plates.

3. Faults are areas where the earth’s plates come together.

4. The shaking produced by earthquakes is caused by seismic waves.

5. The Primary wave (P Wave) is the fastest seismic wave.

6. P Waves push and pull rocks.

7. P Waves cause the booming sounds heard during an earthquake.

8. The booming sounds are the results of P Waves being transmitted into the atmosphere as Sound Waves.

9. The Secondary Waves or Shear Waves (S Waves) are the slowest of the waves.

10. S Waves cannot travel through liquids.

11. P Waves shake the ground vertically and horizontally.

12. P and S Waves are Body Waves.

13. Body Waves are reflected and change to different forms of Surface Waves.

14. The focus is the place in the Earth’s crust where the earthquake begins.

15. The epicenter is the area vertically above the focus on the surface of the earth

16. Earthquakes are measured by the Richter scale.

17. The higher the number on the Richter scale the more intense the earth­quake is.

18. Small earthquakes occur frequently but are not felt by citizens.

19. A Seismograph is an instrument that detects earthquakes.

20. A Seismometer is the buried sensor of the seismograph.

21. Earthquakes are pinpointed by using a process known as Triangulation.

22. Earthquakes can cause a tsunami.

23. Earthquakes may cause fissures of cracks in the Earth’s surface.

24. More damage is caused from earthquakes in larger cities.

25. Earthquakes can rupture gas, water, and sewage lines causing fires, flood­ing, and contamination of water supplies.

26. Every state in the United States is vulnerable to having an Earthquake.

27. Earthquakes usually last less than a minute.

28. Aftershocks can be felt for many days after the initial earthquake.

29. It is not possible to predict when an earthquake will occur.

30. The highest recorded earthquake on the Richter scale is 8.9.

31. Where an earthquake has occurred, an earthquake will occur again.

Effects of Earthquakes:

Ground Shaking:

Violent ground shaking could last for up to a minute in a large earthquake. It may be very difficult to remain standing during the earthquake. Several hun­dred aftershocks could be felt in the weeks following the main quake.

Slope Failure (landslides):

Damage from earthquake-induced landslides can range from severely weak­ened foundations and structural failures, to total destruction.


Ground-shaking causes some soils to behave like a liquid, causing structures to sink, tilt or topple over.

Fault Movement:

A rupture of the fault could involve horizontal and/or vertical movement of sev­eral metres. This could cause buildings, roads, water mains, gas lines and power cables that cross the fault line to be displaced.

Major Recorded Earthquakes:

Year Location
856 Corinth, Greece
1290 Hopeh Province, China
1293 Kamakura, Japan
1531 Lisbon, Portugal
1556 Shensi Province, China
1667 Shemaka, Russia
1693 Catania, Italy
1737 Kolkata, India
1755 Lisbon, Portugal
1759 Baalbek, Lebanon
1783 Calabria, Italy
1797 Quito, Ecuador
1828 Echigo, Japan
1906 San Francisco, California
1908 Messina, Italy
1915 Avezzano, Italy
1920 Kansu Province, China
1923 Tokyo-Yokohama
1932 Kansu Province, China
1935 Quetta, India (now Pakistan)
1939 Chilian, Chile
Year Location
1960 Agadir, Morocco
1962 Iran
1964 Alaska, U.S.A.
1968 Iran
1970 Peru
1972 Iran
1972 Managua, Nicaragua
1974 Pakistan
1976 Guatemala
1976 Hopeh Province, China
1993 Latur (India):The Latur earth­quake in Maharashtra took a toll of about 10,000 lives.
2001 Bhuj (India):The Bhuj earthquake in Gujarat killed more than 13,000 people and destroyed about 8 lakh houses.
2004 Sumatra (Indonesia):This massive earthquake resulted in massive Tsunami waves which killed more than 1.5 lakh people in many coun­try of South Asia including India. More than 50 lakh people got dis­placed and there was massive loss of property and houses also.

Earthquake Safety Tips:

1. Prepare for an Earthquake Just Like You Prepare for Storms:

A. Look for hazards in your home, workplace, and/or school.

B. Secure all objects capable from falling during an earthquake.

C. Put all breakables in fastened cabinets.

D. Buy flashlights, batteries, and battery powered radios and televisions.

E. Have a fire extinguisher and first aid kit available.

F. Have several gallons of bottled water on hand.

G. Have charcoal and/or propane in order to cook in case of loss of electric­ity.

H. Have canned foods available.

I. Have an Earthquake Family Plan outlining where to go in the house (Safe spots) as well as meeting places after the quake.

J. Have Earthquake Drills to practice the Family Earthquake Plan.

2. During an Earthquake:

A. Stay Calm.

B. Follow the Earthquake Family Plan.

C. Duck and Cover.

D. Do not try to enter or leave any building.

3. After an Earthquake:

A. Check for injuries.

B. Listen to the radio and/or television for important information.

C. Do not drink the water until told that it is safe.

D. Check your location for possible damage and safeness.

E. Relocate if necessary.

F. Call out-of-town friends and family to update them on your safety and location.

7 Responses

  1. why did you post your science essay on earthquakes here?


  2. That is the longest post i have ever seen yet.


  3. i didn’t expect to learn anything while just reading random posts. Now i can get an A+ on my science homework lol


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