Earthquake Facts

An undersea earthquake in the Indian Ocean triggered a series of devastating tsunamis on Dec. 26, 2004. The tsunamis struck the coasts of most landmasses bordering the Indian Ocean, bringing 100-foot waves and killing over 225,000 people in 11 countries.

When the Chilean earthquake occurred in 1960, seismographs recorded seismic waves that traveled around the world. These seismic waves shook the entire earth for many days.

Alaska is the most earthquake-prone state and one of the most seismically active regions in the world. The region experiences a magnitude 7.0 earthquake almost every year and a magnitude 8.0 or greater earthquake approximately once every 14 years.

The largest recorded earthquake in the United States was a magnitude 9.2 that struck Prince William Sound, Alaska on March 28, 1964.

The largest recorded earthquake in the world was a magnitude 9.5 in Chile on May 22, 1960.

The deadliest earthquake known hit Shansi, China on January 23, 1556. An estimated 830,000 people died.

Earthquakes kill approximately 8,000 people each year and have caused an estimated 13 million deaths in the past 4,000 years.

Aftershocks occur because the displaced fault line and crust are adjusting to the effects of the main earthquake. Larger earthquakes can have aftershocks that last for years.

Earthquakes are mostly caused by geological faults, but they can also be caused by landslides, nuclear testing, mine tests, and volcanic activity.

The world’s worst landslide started by an earthquake occurred in 1920 in the Kansu province in China. The landslide killed about 200,000 people.

The 1906 earthquake in California was before the Richter scale, but scientists estimate it would rank as a 7.8. As much as 90% of the damage in San Francisco was from fires caused by cracked gas pipes. San Francisco burned for three days and nights.

There are four types of faults in the earth: normal, reverse, thrust, and strike-up.

Nearly 2,000 years ago, a Chinese astronomer named Zhang Heng (A.D. 78-139) invented the world’s first earthquake detector. It could detect earthquakes more than 370 miles (600 km) away.

An earthquake in A.D. 1201 in the eastern Mediterranean is labeled the worst earthquake in history and claimed an estimated one million lives.

Earthquakes occur only in the Earth’s crust. Deep earthquakes originate in crust that is sliding down beneath another tectonic plate. The most devastating earthquakes are those that are strong and shallow with the focus point less than 20 miles (32 km) underground and that occur in highly populated areas.

Englishman John Milne invented the seismograph in 1880.

Before an earthquake, ponds and canals may give off a strange smell. This is caused by the release of gases underground. The temperature of ground water can also become warmer.

An earthquake can release hundreds of times more energy than the nuclear bomb that was dropped on Hiroshima in Japan in 1945.

The San Andreas Fault is moving about 2 inches a year, about the same rate fingernails grow. At this rate, San Francisco and Los Angeles will be next to each other in 15 million years.

The 9.0 earthquake that struck Japan March 11, 2011 was the worst earthquake in Japan’s history. It created a tsunami with waves as high as 30 feet (10 meters) and severely damaged nuclear power plants.

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

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.

Most earthquakes and happen in the United States are near oil fracking wells and geothermal plants.

The National Earthquake Information Center (NEIC) records an average of 20,000 earthquakes every year (about 50 a day) around the world. There are, however, millions of earthquakes estimated to occur every year that are too weak to be recorded.