17 Powerful Earthquake Facts From Science & History

Discover a number of interesting scientific facts about earthquakes.

• Earthquakes are caused by a sudden slip (displacement) along a fault, which is an area of fracture or stress in the Earth's crust.
• An earthquake's epicenter is the place on the surface of the Earth directly above where an earthquake originates.
• The term hypocenter is used to describe the place below the surface of the Earth where the earthquake begins. It is directly beneath the epicenter.
• A device called a seismograph is used to identify, record and measure the duration and intensity of an earthquake.
• Seismic waves are the energy that results from the sudden breaking of rock that takes place in the Earth during an earthquake. These waves are what a seismograph measures.
  
• Earthquakes are measured in terms of magnitude, which is a value that quantifies their relative size. It is based on maximum motion caused by the earthquake, as recorded by a seismograph.
  
• Approximately half a million earthquakes take place each year. Of those, around 100,000 can be felt. though only 100 result in damage.
• A large earthquake can be preceded by a foreshock. It takes place in the same area as the larger quake (which is called the mainshock) but has a smaller magnitude.
• A large earthquake can also be followed by an aftershock, which is a smaller magnitude quake that occurs not long after the mainshock.
• Alaska experiences more earthquakes than any other state in the United States (U.S.).
• While the total number of earthquakes is higher in Alaska than in California, the state of California has the most earthquakes that cause damage.

There have been a number of significant and record-setting earthquakes throughout history. The statistics provided here are accurate as of January 2021.

• In 1769, the Portola expedition reported what became the first scientifically recorded earthquake. It occurred about 30 miles away from what is now Los Angeles, California.
  
• The San Francisco earthquake of 1906 is significant due to its size. Its magnitude is estimated to have been 7.9, but it ruptured nearly 300 miles of the San Andreas fault. It was felt throughout all of California into parts of Oregon and Nevada.
  
• The Richter magnitude scale was developed in 1935 by Charles Richter, a seismologist and physicist at the California Institute of Technology.
• Chile experienced a 9.5 magnitude earthquake in 1960. It remains the strongest earthquake on record.
  
• Prince William Sound in Alaska experienced a 9.2 magnitude earthquake in 1964. It is the largest earthquake recorded in the United States of America.
• During the 1970s, the moment magnitude scale (MMS) was developed. It is considered more accurate for measuring large earthquakes than the Richter scale.

No discussion of earthquake facts would be complete without a reminder to take steps to stay safe in the event of an earthquake. Get prepared by assembling an earthquake emergency kit and follow key earthquake safety tips and precautions. Be sure to heed official warnings issued by local emergency management officials.

If you remain interested in earthquakes and want to study them as your occupation, you may want to consider becoming a seismologist. Seismology is a specialized field within geophysics. Most professional seismologists major in geology, physics, geophysics, or mathematics in college. If seismology sounds like an interesting career to you, take as many classes related to those areas as possible in high school so you'll have the foundational knowledge necessary to succeed in college-level courses when the time comes.

Now that you have an understanding of some powerful facts about earthquakes, expand your knowledge by discovering how underwater earthquakes can contribute to tsunamis. Start by exploring these key tsunami facts. Enhance what you learn there by exploring examples of oceans and seas. Everything you learn about earthquakes and related geological events will expand your knowledge of physical science and the natural world.