Earthquake

Facts
The Modified Mercalli scale & the Richter scale
Earthquake rose
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Earthquake emergency shoppe
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Facts

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.
The Richter Scale is not a physical measuring instrument but a mathematical formula. The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. Adjustments are included for the variation in the distance between the various seismographs & the epicenter of the earthquakes.
On the Richter Scale, magnitude is expressed in whole numbers & 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.
Another scale of earthquake measurement is called the Mercalli scale, invented by Giuseppe Mercalli in 1902. This scale estimates the severity of the quake based on the observations of the people who have experienced the earthquake.
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 as 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 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.

The Modified Mercalli scale & the Richter scale

Mercalli Intensity Richter Scale Magnitude Witness Observations

I Feeble 1 to 2 Felt by very few people; barely noticeable.

II Slight 2 to 3 Felt by a few people, especially on upper floors.

III Moderate 3 to 4 Noticeable indoors, especially on upperfloors, but may not be recognized as an earthquake.

IV Moderate 4.3 Felt by many indoors, few outdoors. May feel like heavy truck passing by.

V Rather Strong 4.4 - 4.8 Felt by almost everyone, some people awakened. Small objects moved. Trees and poles may shake.

VI Strong 4.9 - 5.4 Felt by everyone. Difficult to stand. Some heavy furniture moved, some plaster falls. Chimneys may be slightly damaged.

VII Very Strong 5.5 - 6.1 Slight to moderate damage in well built, ordinary structures. Considerable damage to poorly built structures. Some walls may fall.

VIII Destructive 6.2 - 6.5 Little damage in specially built structures. Considerable damage to ordinary buildings, severe damage to poorly built structures. Some walls collapse.

IX Ruinous 6.6 - 6.9 Considerable damage to specially built structures, buildings shifted off foundations. Ground cracked noticeably. Wholesale destruction. Landslides.

X Disastrous 7.0 - 7.3 Most masonry and frame structures and their foundations destroyed. Ground badly cracked. Landslides. Wholesale destruction.

XI Very Disastrous 7.4 - 8.1 Total damage. Few, if any, structures standing. Bridges destroyed. Wide cracks in ground. Waves seen on ground.

XII Catastrophic > 8.1 Total damage. Waves seen on ground. Objects thrown up into air.

Earthquake rose

On Feburary 28, 2001, a magnitude 6.8 earthquake shook the city of Seattle, some thirty miles below the surface of the earth. The quake was felt as far as 300 miles away from its epicenter. A few miles away from Olympia Washington, the ground moved a bit for more than half a minute.
According to Norman MacLeod, president of Gaelic Wolf Consulting in Port Townsend, Washington, a shop in Port Townsend called "Mind Over Matter" (which has since moved) had a sand tracing pendulum with a pointed weight at the end of a wire suspended over a tray of sand. The vibration of the quake led to an unusual phenomenon - the suspending pendulum actually drew a pattern on the sand dish that resembled a rose and was hence called the Earthquake Rose.
However the American Physical Society's May 2001 newsletter reported that "Sadly, the Earthquake Rose is no more. Shop owner Jason Ward had intended to take a mold of the pattern. But before this could be done, his three-year-old son accidentally kicked the pendulum - and erased the sand's design. At least Ward still has the photographs."
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