By: Jagroop R and Alex K
What Is An Earthquake?
An earthquke is when energy is relased from between tectonic plates. When the energy is released, the ground shakes. Depending on how much energy is released the ground shakes more or less. Almost all earthquakes happen around fault lines. The earthquakes that happen on fault lines are caused by plates pulling, sliding or pushing. An earthquake can have foreshocks. Scientists can not determine a foreshock is a foreshock until the main earthquake occurs. Aftershocks are certain after an earthquake. Aftershocks can occur for weeks, months and even years depending on the size of the main eartthquake.
How Does An Earthquake Happen?
An earthquake occurs when two tectonic plates push, slide or push against each other. An earthquake can also be caused by mine and nuclear testing, landslides and volcanoes. When an earthquake happens, a lot of energy is released abruptly. Energy is released in every direction. The earthquake is felt stronger near the epicenter. Fault lines are very jagged. So when they push, slide or pull against each other the jagged parts make earthquakes. For most of history, people didn't know why earthquakes happen. Most people thought mythological creatures were holding the earth. If any creature moved there would be an earthquake.
Parts Of An Earthquake
There are four parts of an earthquake. The epicenter, hypocenter or focus, sesimic waves and fault lines. The hypocenter is the place where the earthquake starts underground. The epicenter is directly above the focus but on the ground. Sesimic waves are energy being released in all directions from focus. Fault lines are the place where the earthquake is made by plates pushing, sliding or pulling.
Tectonic Plates And Fault Lines
Tectonic plates are giant slabs of rock. The plates are always moving. Tectonic plates move 10 cm per year, about the same rate your fingernails grow. The plates are moving because of the magma underneath them. The plates may sink into the magma and melt a little bit. A place where two plates meet are called plate boundary. There are two types of plate boundaries, convergent plate boundary and divergent plate boundary. A convergent plate boundary is where one plate slips under the other plate. A divergent plate boundary is where two plates are being pulled away from each other. A divergent plate boundary can make volcanoes when the magma comes up from under the plates.
Top Five Highest Recorded Earthquakes
No. 5: Kamchatka, Russia; 8.9 magnitude; 10,000 deaths
No 4: North Coast of Japan; 9.0 magnitude; 15,891 deaths
No. 3 Northern Sumatra, Indonesia; 9.1 magnitude; 227,898 deaths
No.2 Prince William Sound; 9.2 magnitude; 131 deaths
No. 1 Southern Chile; 9.5 magnitude; 1,655 deaths
Moment Magnitude Scale
The moment magnitude scale measures the size of earthquakes. It measures it by measuring the energy released by the earthquake. Scientists can then put the earthquake into a number such as 6.9.
0.1 -2.5 earthquakes mostly not felt and about 900,000 hit earth each year.
2.6-5.4 earthquakes are minor. They can cause minor damage and about 30,000 hit earth each year
5.5-6.0 earthquakes are moderate. These earthquakes can cause moderate damage and about 500 earthquakes hit earth each year.
6.1-6.9 earthquakes are strong. They can cause a lot of damage and about 100 hit earth each year.
7.0-7.9 are major earthquakes. These earthquakes can cause serious damage and about 20 hit earth each year.
8.0+ earthquakes are great earthquakes. They can cause great damage and about 1 hit earth each year.
1. Earthquakes on the moon are called moonquakes.
2. The most earthquake-prone state is Alaska.
3. The Japanese earthquake moved the island closer to the U.S.
4. Japan is the most earthquake-prone country in the world.