Please watch a scientists explaining about earthquakes.

No, there are actually a lot of earthquakes that are never even felt! Most earthquakes that get reported in the news are very powerful, but technically an earthquake occurs whenever there is a sudden stress change in the earth, often caused by a slip along a fault line. There is no requirement that this stress change be large in order to get the name “earthquake.”

Thousands of imperceptible earthquakes actually happen every day, so powerful ones are relatively rare. Below is a scale describing the power of earthquakes, along with how many occur each year:

Magnitude	Earthquake Effects	Estimated Number Each Year
2.5 or less	Usually not felt, but can be recorded by seismograph.	900,000
2.5 to 5.4	Often felt, but only causes minor damage.	30,000
5.5 to 6.0	Slight damage to buildings and other structures.	500
6.1 to 6.9	May cause a lot of damage in very populated areas.	100
7.0 to 7.9	Major earthquake. Serious damage.	20
8.0 or greater	Great earthquake. Can totally destroy communities near the epicenter.	One every 5 to 10 years

Hi Gandhar, living in California, this is a really important question to address! Simply put, all earthquakes are powerful but some are way more powerful than others.

Earthquakes result from slipping of the tectonic plates that make up our earth along fault lines (where two plates meet). When they slip, a lot of energy is released because the plates are so big and pushing against one another with a lot of force. That energy travels to the Earth's surface and becomes an earthquake. What really determines the strength of the earthquake is how big the slip was; the bigger the slip, the bigger the Earthquake.

There are hundreds of thousands of earthquakes per year, but most of them are quite minor and may not even be felt. As a general rule, the more powerful an earthquake, the rarer. Earthquakes are typically measured in magnitude, which is a scale based on the area of fault that slipped to cause the earthquake, how much it moved, and how much force was needed to move it. The amount of shaking that you feel at the surface of the earth depends on the magnitude, but also on how deep the fault was and what kinds of rocks or sediments are in the ground between you and the fault. An earthquake of magnitude 2.5 is usually unnoticeable to people but can be recorded by seismographs that measure earthquakes. These happen on a regular basis. An earthquake of magnitude 8 or higher can destroy cities, but the whole world may go 5 to 10 years without experiencing one.

No. Thee are earthquakes of all sizes. Once I thought I felt an earthquake, so I went to the internet and typed 'earthquake' and found that there had just been a little earthquake near me. Another time I was collecting an image in a microscope, and the earthquake showed up as just a little wiggle in the picture from the microscope.

No. Most earthquakes are very weak. Powerful earthquakes are very rare. The only reason why you read about the powerful ones is because the powerful ones are the ones that cause damage, and because the Earth is big enough that even rare powerful earthquakes still happen fairly often - but the weak earthquakes happen much, much more.

As an example, the National Earthquake Information Center records on average about fifty earthquakes each day in the state of California. Most are so weak that you would never feel them.