Photograph by Mosanori Kobayashi

Earthquakes, also called temblors, can be so tremendously destructive, it’s hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors.

Some 80 percent of all the planet's earthquakes occur along the rim of the Pacific Ocean, called the "Ring of Fire" because of the preponderance of volcanic activity there as well. Most earthquakes occur at fault zones, where tectonic plates—giant rock slabs that make up the Earth's upper layer—collide or slide against each other. These impacts are usually gradual and unnoticeable on the surface; however, immense stress can build up between plates. When this stress is released quickly, it sends massive vibrations, called seismic waves, often hundreds of miles through the rock and up to the surface. Other quakes can occur far from faults zones when plates are stretched or squeezed.

Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 5 is considered minor or light; 5 to 7 is moderate to strong; 7 to 8 is major; and 8 or more is great.

On average, a magnitude 8 quake strikes somewhere every year and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis. Smaller temblors that usually occur in the days following a large earthquake can complicate rescue efforts and cause further death and destruction.

Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.

Share

More About Earthquakes

  • Photo: Tsunami relief efforts continue in Sri Lanka

    Photo Gallery: 2004 Indian Ocean Tsunami

    The Indian Ocean tsunami of 2004 struck without warning, killing thousands. See photos of the devastating destruction.

  • Photo: A satellite image of Gleebruk, Indonesia after tsunami.

    Photo Gallery: Tsunami Aerial Views

    Check out these aerial photos for a birds-eye-view of the Indian Ocean Tsunami.

  • Photo: Collapsed bridge

    Earthquakes

    Earthquakes are a naturally destructive effect of Earth's constantly changing surface. Shake up your day with these devastating photos of past earthquakes.

How to Feed Our Growing Planet

  • hub_tease2.jpg

    Feed the World

    National Geographic explores how we can feed the growing population without overwhelming the planet in our food series.

See blogs, stories, photos, and news » »

@NatGeoGreen on Twitter

The Great Energy Challenge

Step Up to the Challenge »

The World's Water

  • change-the-course-dry-co.jpg

    Help Save the Colorado River

    NG's new Change the Course campaign launches. When individuals pledge to use less water in their own lives, our partners carry out restoration work in the Colorado River Basin.

  • water-grabs-mali-4x3.jpg

    Water Grabbers: A Global Rush on Freshwater

    A special series on how grabbing water from poor people and future generations threatens global food security, environmental sustainability, and local cultures.

Learn More About Freshwater »