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.
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.
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.
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!
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.
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.
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.
Aren’t these earthquake facts fascinating? We are not done yet! There are several other interesting facts that we will be mentioning in our next article. Stay tuned!
- 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.