Scientists compare the earth to a living organism. Earthquakes, then, are merely the planet's growing pains. Around the world, earthquakes are a constant occurrence -- only occasionally do they make themselves felt on the surface.
When the earth begins to rumble, however, get ready to rock and roll!
HOVER over the image to SEE and HEAR an earthquake in action. (Luckily,
most modern skyscrapers are reinforced against subterranean shaking!)
Earthquakes happen when the earth's crust - made up of tectonic plates - shift enough to cause the ground to undulate in seismic waves. Depending on their strength, they may occur unnoticed. At other times they can result in catastrophic damage.
The San Francisco earthquake, for example, was the most destructive in U.S. history and caused the deaths of some 3,000 people and $400 million in damages in 1906.
When they erupt offshore, earthquakes may also cause the ocean to violently sway and pitch, resulting in the massive Indian Ocean tsunami that decimated entire communities in 2004.
Most recently, another catastrophic earthquake measuring 7.1 in magnitude on the Richter scale caused massive damage along the northern coast of Japan, which triggered yet another deadly tsunami in April 2011.
How to survive an earthquake
While earthquakes and tsunamis sometimes go hand-in-hand (especially when they occur under the ocean or along coastal areas), most destruction and loss of life occurs from inland earthquakes.
In larger cities, especially, care should always be taken to guard against falling debris from buildings or highways. No matter where the location, an emergency earthquake kit should also always be on hand in earthquake-prone areas to prepare for loss of utilities and other public services in the aftermath.
Also remember these practical tips for keeping safe during an earthquake:
• If you are indoors when an earthquake hits, stand in a doorway or crouch under a desk or table away from windows, mirrors or glass dividers.
• Outside, stay away from buildings, trees, telephone and electrical lines.
• On the road, avoid highway underpasses and overpasses. Once you find a safe area, stay in your car.
Around the Web, discover more about earthquakes with details on the science behind them, instructional videos, related safety guides, and kid-friendly educational resources ....
Earthquakes - Online publication from the U.S. Geological Survey covering where and how earthquakes happen, famous earthquakes occurrences and historical data, plate tectonics and earthquake measurement & predictions, related illustrations & photos.
SF Gate: Earthquakes - Extensive guide from the San Francisco Chronicle with safety and preparedness advice, retrofitting tips for those in earthquake-prone areas, earthquake photos, videos, seismograph images, charts & maps, and a complete
history of the 1906 quake with related resources.
Savage Earth: Restless Planet - Earthquakes - Companion site to the PBS special including photos & animations, facts on quake predictions, guides to building earthquake-proof buildings, and more on the effects of volcanoes and tsunamis.
What causes an earthquake? - Good fact sheet on the topic with a discussion on earthquake terminology, plate tectonics, seismic shock waves, and a comparison between tectonic and volcanic earthquakes.
Earthquake Country - The complete handbook to earthquake safety with related facts, Q&A, photos & educational videos.
Earthquakes for Kids - Fascinating and entertaining look at the power of nature with related photos, science fair project ideas, cool earthquake facts, animations and interactive games & puzzles with related resources.