Earthquake Facts

•Human beings can detect sounds in the frequency range 20-10,000 Hertz. If a P wave refracts out of the rock surface into the air, and it has a frequency in the audible range, it will be heard as a rumble. Most earthquake waves have a frequency of less than 20 Hz, so the waves themselves are usually not heard. Most of the rumbling noise heard during an earthquake is the building and its contents moving.

•A magnitude 9.5 earthquake in Chile in 1960 was the largest known earthquake and resulted in over 6,000 deaths. It triggered a tsunami or seismic wave (incorrectly known as a tidal wave) that killed people as far away as Hawaii and Japan.

•The world's deadliest recorded earthquake occurred in 1556 in central China killing an estimated 830,000 people. In 1976 another deadly earthquake struck in Tangshan, China, where more than 250,000 people were killed.

•Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 5 would be 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 worldwide annually in earthquakes. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis.

•The longest earthquake ever recorded was the Sumatra earthquake of December 26 2004. The Magnitude 9.3 earthquake lasted for ten minutes where as most normal earthquakes last only a few seconds. The energy released equaled the power of a 100 gigatons bomb. This quake also created the longest fault ever recorded in the sea floor at about 800 miles long. Nearly 300,000 people lost their lives as a result.

•Changes in animal behavior cannot be used to predict earthquakes. Even though there have been documented cases of unusual animal behavior prior to earthquakes.

•There are over a million quakes occurring annually, including those too small to be felt.

•The shaking of a magnitude 7 is 10 times greater than a magnitude 6 and 100 times greater than a magnitude 5

•It is estimated that there are 500,000 detectable earthquakes in the world each year. 100,000 of those can be felt, and 100 of them cause damage.

•The energy of the 1964 Alaskan earthquake of Magnitude 9.2 was the same as that in 73,000 Hiroshima-size atomic bombs.

•The costliest natural disaster on the planet was the Kobe Earthquake that hit in January 1995. Over 100 billion dollars worth of damage was caused by the quake and the subsequent fires.