Facts About Earthquakes

• The Richter Scale is not a physical measuring instrument but a mathematical formula where the magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs.
• The Richter Scale was invented by an American scientist Charles Richter along with a fellow colleague Beno Gutenberg, both of the California Institute of Technology in 1935 to compare the size of earthquakes. It measures how much the ground shakes 60 miles from the earthquake’s epicenter.

  This measuring scale not a physical measuring instrument but a mathematical formula. On the Richter Scale, magnitude is expressed in whole numbers and decimal fractions. Each unit on this scale is equivalent to a power factor of about 32. That means, a reading of 5 on the Richter Scale is 32 times more powerful than a 4.

• The first known measuring instrument was invented around 132 A.D. by Zhang Heng, a Chinese philosopher and scientist. The instrument was called the “dragon jar” which was a bronze jar with a central pendulum inside. Eight dragonheads surround the exterior of the jar. Each of the dragon had a ball in its mouth. Directly beneath each dragon was a open-mouthed frog at the base of the jar.
  

  The direction of the earthquake was indicated by which of the dragon had dropped a ball. This ingenious invention was said to have detected an earthquake over 600 kilometers (372 miles) away.

• The largest recorded earthquake was the Great Chilean Earthquake of May 22, 1960 in Chile. That earthquake measured 9.5 on the Richter scale.
• According to U.S. Geological Survey (USGS), the series of three most powerful magnitude-8 earthquakes in the United States occured over a 3-month period from 1811 to 1812 along the New Madrid Fault in Missouri. The New Madrid magnitude 8.0 earthquake of December 1811 rang church bells in Boston, Massachusetts, some 1,000 miles away. Damage was reported as far away as Charleston, South Carolina, and Washington, D.C.
• The deadliest recorded earthquake struck in 1557 in central China, in a region where most people lived in caves carved from soft rock. These dwellings collapsed during the earthquake, killing an estimated 830,000 people.
• In 1976 a magnitude 7.8 earthquake struck in Tangshan, China, where more than 250,000 people were killed.
• On 17 January, 1995, a major 6.9 magnitude earthquake struck near the City of Kobe, Japan.
• In earthquake-prone Japan, about 1,000 tremors occur in the country each year. To prepare for an emergency, at the Tokyo Fire Department’s Bosaikan center, visitors can experience a simulated magnitude 7 quake and learn many other survival skills (e.g. mouth-to-mouth resuscitation). On sale at the center is a fire-resistant backpack packed with items such as gas masks and can food.

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