What is an Earthquake?

The sudden trembling or shaking of the tectonic plates of Earth resulting in the shaking of the ground is known as Earthquake.

The trembling or shaking suddenly releases enormous amounts of energy stored in Earth’s crust. This energy creates seismic waves.

Earthquakes can be natural or man-made, and they can lead to immense damage of houses, property, and life. They also lead to further breakdown of the surface of the Earth.

Volcanoes are not the only destructive weapons in Mother Nature’s arsenal. Yet another catastrophic force is the earthquake. Believe it or not, earthquakes have been responsible for killing over 13 million people in last 4,000 years. Well, that’s an estimated figure.

The actual figure may be way more than that. Anyway, we hear about earthquakes killing people every year but did you ever wonder, what causes them? Where do they originate from?

Do earthquakes follow any specific pattern? Today we are here with a list of facts that will answer all those questions. So, if your mind is curious enough, we invite you on this journey of 30 interesting earthquake facts.

Earthquake Facts: 1-5

1. Our earth consists of several tectonic plates. These plates keep moving constantly. As these plates move, huge pressure is generated which create cracks on earth’s surface or crust. This pressure is then released through these cracks. The pressure actually moves through earth in form of waves (seismic waves) that we know as earthquakes.

2. It is not that only tectonic plates’ movements are responsible for earthquakes. Even meteor impacts and volcanic eruptions can cause earthquakes. Even mine tests and nuclear testing can cause earthquakes.

3. Even gravitational pulls of moon and sun cause earthquakes. They actually cause minor tides on earth’s crust. However, these tides are too small to be felt.

4. Millions of earthquakes occur each year. Majority of these are too weak to be recorded. However, NEIC or National Earthquake Information Center records around 20,000 quakes every year of which only 100 or so are capable of causing damage.

5. Interestingly, when earthquake occurs, the shaking ground itself is not responsible for killing people. Collapse of buildings, landslides, avalanches, volcanic eruptions and tsunamis triggered by earthquakes are actually responsible for killing people.

Earthquake Facts: 6-10

6. Majority of the earthquakes take place along the edges of the 7 major or primary tectonic plates of earth.

7. Earth’s 80% of earthquakes occur near Pacific Ring of Fire. It is a region in Pacific Ocean which resembles the shape of a horse-shoe. This is the region where many of earth’s tectonic plates meet.

8. Second to Pacific Ring of Fire is the Alpide Belt region where major earthquakes take place. Alpide Belt covers countries like India, Turkey and Pakistan.

9. An earthquake is capable of releasing energy which is 100 times more powerful than the energy released by atomic bomb dropped on Japan’ Hiroshima in 1945.

10. Canals and ponds may start releasing strange smell before an earthquake. This usually happens because underground gases are released. Ground water may also experience an increase in temperature just before an earthquake.

Earthquake Facts: 11-15

11. A major earthquake is usually preceded by a series of smaller quakes. These quakes are known as foreshocks. The major earthquake is succeeded by a series of small quakes which are known as aftershocks. Aftershocks may last for days and even weeks and even years.

12. An earthquake may last anywhere between a few seconds and a few minutes. The longest earthquake in recorded history took place in 2004 in Indian Ocean. It lasted for 10 minutes.

13. The Indian Ocean earthquake on December 26, 2004 triggered a series of tsunamis. These tsunamis were devastating and had hit most of the landmasses that border the Indian Ocean. 11 countries were hit and 225,000 lives were lost that year. Tsunami waves as high as 100 feet tall had hit several coastlines.

14. The power generated by the Indian Ocean earthquake in 2004 was enough to supply power 100% business and domestic units throughout United States for a stretch of 3 days.

15. An earthquake occurring on ocean bed (like that of the Indian Ocean earthquake of 2004) can lead to tsunamis that are capable of traveling in all directions at a speed of 600 miles or 970 kilometers an hour. As the tsunami approaches a coastline, the waves can reach a height of 100 feet!

Earthquake Facts: 16-20

16. Seismic waves can travel at a very high speed. The fastest seismic wave recorded till date is 225 miles or 360 kilometers an hour.

17. World’s one of the most earthquake-prone nations is Japan. The country experiences thousands of earthquakes each year but most of them are too weak to cause massive damage.

18. Earth’s Northern Hemisphere records more earthquakes than Southern Hemisphere.

19. We come across the term epicenter very often but what is it? Epicenter is the point on ground right above the focus of the earthquake. The actual focus of the earthquake is underneath the ground where the earthquake originates and the initial rupture occurs. That focus point is known as hypocenter.

20. The aftershocks we mentioned earlier are actually a result of earth’s attempts to adjust its crust and fault lines that are displaced by the main shock.

Earthquake Facts: 21-25

21. Earthquakes produce a type of wave known as Rayleigh wave. Rayleigh waves are surface acoustic waves that travel through earth’s surface. These shockwaves are capable of traveling upward and reach the ionosphere of earth’s atmosphere. Interestingly ionosphere is around 80-480 kilometers or 50-300 miles above the surface of earth.

22. During 1930s Richter Scale was used for measuring the size of earthquakes. This scale was however later replaced by MMS or Moment Magnitude Scale during 1970s. MMS actually measure the size of an earthquake in terms of energy released by it.

23. We mentioned earlier that an earthquake can last anywhere between a few seconds and few minutes. However, the average length of an earthquake is about 60 seconds or 1 minute.

24. Do you know what a Pagoda is? It is actually a tiered building. Read more about Pagodas here. It is weird to know that the shape of a Pagoda is capable of resisting earthquake induced damage.

25. Tectonic plates move at a very slow pace. They move at a rate of 3 inches per year. A movement of just 20 centimeters (3 inches and 3 centimeters) is enough to cause a massive earthquake.

Earthquake Facts: 26-30

26. Earthquakes do not occur underneath the ground. It is always the crust of the earth that shakes. What is referred to as deep earthquake is actually an earthquake occurring on the crust but the only difference is that the crust slides down below another tectonic plate.

27. Earthquakes are extremely devastating when they occur in areas that are highly populated and have hypocenters of less than 20 miles or 32 kilometers underground.

28. While some scientists believe that there are some animals that can sense weak foreshocks, there are other scientists who believe that these animals are actually capable of sensing electrical signals which are set off when tectonic plates shift.

29. Just like on earth, earthquakes occur on moon but they are referred to as moonquakes. Moonquakes are usually not as strong as earthquakes.

30. Earthquakes occurring on one side of earth are capable of shaking earth’s other side. The 2004 Indian Ocean earthquake, according to Seismologists, weakened the famous San Andreas Fault of California. Similarly, the earthquake that occurred in Chile in 1960 was so massive that the entire earth was shaken for several days. This phenomenon, known as oscillation, was measured by seismic stations located all over the world.

Earthquake Facts: 31-35

31. According to Japanese Mythology, earthquakes are caused by Namazu. Namazu in Japan is a mythological giant catfish that is responsible for this disastrous force of nature.

32. According to Hindu Mythology, the entire earth is standing on the back of 8 gigantic elephants. These elephants are in turn standing on back of a gigantic turtle. The turtle in turn is standing on the coils of a gigantic snake. Earthquakes, according to Hindu Mythology, occur when any of these animals move.

33. According to ancient Greeks, earthquakes were caused when Poseidon (their god of sea) became angry and would strike the earth with his powerful trident. According to Greeks, the behavior of Poseidon was violent and unpredictable and hence, they gave him the name ‘Earth-Shaker’. Ancient Greeks also believed that earthquakes were a result of wind rushing out of caves located inside earth.

34. The ‘best ever record’ of an earthquake took place in Japan in 2011. The reason why it is termed as ‘best ever record’ is that Japan has installed very high-tech sensors throughout the country to identify any earthquake threats. They did this because Japan is world’s one of the most earthquake-prone countries in the world.

35. Earthquakes can change the duration of day and night. The 2011 earthquake in Japan caused mass of earth to shift towards its center. As a result, earth started spinning slightly faster. After the earthquake, the day has been shortened by 1.8 microseconds.

Interesting Earthquake Facts: 36-40

36. The 2004 earthquake in Indian Ocean (also known as Sumatra earthquake) shortened the length of the day by 6.8 microseconds.

37. After the 2011 earthquake in Japan, a massive rift was created on the ocean bed. The rift was created 15 miles under the ocean and it is 93 miles wide and 186 miles long.

38. The 2011 earthquake in Japan was the worst ever earthquake in Japan’s history. The byproduct of the earthquake was a tsunami with 30 feet tall waves that seriously damaged a nuclear power plant in Japan.

39. The earthquake in Japan in 2011 had a magnitude of 9.0 and it shifted Japan closer to United States. It also shifted the axis of earth by 6.5 inches.

40. One of the earliest recorded earthquakes in human history dates back to 1831 B.C. It occurred in China’s Shandong province.

Earthquake Facts: 41-45

41. Alaska is world’s most earthquake-prone state.

42. The first ever recorded earthquake in California was in 1769 A.D. The earthquake was recorded by Gaspar de Portola, who was not only a Spanish military officer but was also an explorer.

43. Alaska’s 9.2 magnitude earthquake in 1964 was devastating. The streets dropped by 6 meters (20 feet) below the normal level. The earthquake occurred for 4 minutes and was responsible for causing floods in Hawaiian coasts that were 3,100 miles away from the epicenter. It was the largest earthquake ever recorded in the U.S.

44. In 1775, Portugal’s Lisbon experienced a devastating earthquake. So massive was the earthquake that Loch Ness in Scotland (1,240 miles) away from Portugal experienced waves on earth’s surface.

45. The fame of being the worst ever earthquake in human history goes to eastern Mediterranean earthquake of 1201 A.D. which killed about 1 million people. The earthquake occurred in SW Syria.

Earthquake Facts: 46-50

46. We said in our previous post on earthquakes that they can set off volcanic eruptions. This actually happened twice – once in 1980 when Mount St. Helens erupted and next in 2002 when Mount Etna erupted.

47. The first ever seismometer to be invented was in 132 A.D. It was invented by a Chinese astronomer named Zhang Heng. It was named as ‘houfeng didongyi’ which in English translates to ‘earthquake weathervane’. It was an urn-shaped device made of bronze and had a swinging pendulum inside it. The device was actually pretty accurate and was capable of detecting earthquake from a distance of 370 miles or 600 kilometers!

48. In recent history, the largest recorded earthquake took place in 1960 in Chile. It had a magnitude of 9.5 and it was responsible for creating giant waves in ocean as far as 10,000 kilometers or 6,000 miles away.

49. The first every major earthquake disaster to be recorded in photographs was that of California in 1906. It occurred before the invention of Richter Scale but scientists think that it was of 7.8 magnitude on Richter Scale.

50. In 1771, an earthquake in Japan resulted in a tsunami that had the highest ever recorded wave. The wave was 85 meters or 278 feet tall.

Earthquake Facts: 51-55

51. The worst ever landslide caused by an earthquake was in 1920. The earthquake occurred in China’s Kansu province and the resulting landslide was responsible for killing 200,000 people.

52. The worst ever avalanche to be caused by an earthquake was in 1970 A.D. in Peru. The avalanche had a wave of 250 feet of rock, mud and ice rushing down the Huascaran Mountain at a speed of 400 kilometers or 250 miles an hour. Luckily the area was less populated but still, the avalanche killed well over 18,000 people.

53. California’s Parkfield holds the title of ‘The Earthquake Capital of the World’.

54. The Sumatra earthquake of 2004 (the Indian Ocean earthquake) was so catastrophic that the midsection bulge of the earth (the earth is slightly bulged in the midsection in relation to pole-to-pole measurement) was reduced slightly. As a result, our earth is little rounder than what it was prior to that earthquake.

55. In 2010, Chile experienced an earthquake of magnitude 8.8. The earth’s crust was ripped off as a result of which, the city named Concepción moved 10 feet towards the west.

Okay, this concludes our 55 interesting earthquake facts. However, there are more. So, we decided to give you a bonus reading material. Here is the list of the most massive earthquakes in recorded history:

  • 1139 CE: Earthquake in Ganja, Azerbaijan killed 300,000 people.
  • 1201 CE: Earthquake in SW Syria killed 1,100,000 people.
  • 1556 CE: Earthquake in China’s Shaanxi Province killed 800,000 people.
  • 1662 CE: Earthquake in China killed 300,000 people.
  • 1923 CE: The Great Kanto Earthquake in Japan’s Tokyo killed 140,000 people.
  • 1978 CE: Earthquake in Tangshan, China killed 242,769 people.
  • 2004 CE: The Sumatra earthquake killed 230,000 people.
  • 2010 CE: The Haiti earthquake killed 230,000 people.

Here is the list of top 5 earthquakes since 1900 CE in terms of magnitude:

  • 1952: Kamchatka, Russia – Earthquake of 9.0 on MMS scale.
  • 1960: Valdivia, Chile – Earthquake of 9.5 on MMS scale.
  • 1964: Prince William Sound, Alaska – Earthquake of 9.2 on MMS scale.
  • 2004: Sumatra, Indonesia – Earthquake of 9.1 on MMS scale.
  • 2011: Sendai, Japan – Earthquake of 9.0 on MMS scale.

Alright! We will stop here. If we continue, it may lead to brainquakes! 🙂

Earthquake Frequently Asked Questions

What is an earthquake?

Earthquake refers to the sudden release of enormous amounts of energy stored in crust of Earth.

During earthquake, the tectonic plates shake or tremble, causing the ground to shake.

Earthquakes can be natural or man-made, and they have the ability to cause immense damage to property and life.

Earthquakes are also known for breaking down the surface of the Earth, creating new landmasses.

How many types of earthquakes are there?

There are four types of earthquakes. They are: explosion, collapse, volcanic, and tectonic.

What is explosion earthquake?

The earthquake caused by detonation of a chemical or a device is known as explosion earthquake.

What is collapse earthquake?

Small earthquakes in underground mines and caverns caused by seismic waves generated by explosion of rocks on the surface are known as collapse earthquakes.

What is volcanic earthquake?

A volcanic earthquake is a seismic disturbance that is caused by a direct action of a volcanic force. Also, if the origin of the earthquake lies near or under an active, extinct, or a dormant volcano, it is known as a volcanic earthquake.

What is tectonic earthquake?

This is a type of earthquake in which the crust of the Earth breaks because of geological forces acting on rocks and adjoining plates, causing chemical and physical changes.

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  • Fact Retriever
  • Do Something
  • Live Science
  • Wikipedia
  • Bolt, Bruce A. 2006. Earthquakes. 5th Ed. New York, NY: W.H. Freeman Company.
  • Colson Mary. 2006. Shaky Ground: Earthquakes. Chicago, IL: Raintree.
  • Fradin, Judy and Dennis. 2008. Earthquakes: Witness to Disaster. Washington D.C.: National Geographic.
  • Page, Jake and Charles Officer. 2004. The Big One. New York, NY: Houghton Mifflin Company.
  • Goodwin, Liz. “Japan’s Earthquake Shifted Balance of the Planet.” Yahoo!News. March 14 2011. Accessed: June 1, 2014.

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