Jay's Earthquake Simulator


Before there were seismometers which could measure the vibration of the earth caused by earthquakes, scientists used descriptive measures of the effects of the vibration as a means of quantifying their size or severity. One of the first intensity scales was developed by the Italian scientist De Rossi and the Swiss scientist Forel, known as the Rossi-Forrel scale. In 1902 the Italian scientist Mercalli improved this scale, and in 1931 the American scientists H.O. Wood and F. Neumann adapted the scale for use in California. The scale is now known as the Modified Mercalli Intensity scale.


  Modified Mercalli Intensity Scale of Earthquake Damage

Total destruction; "waves" seen on ground surface; river courses altered; vision distorted

Railway tracks bend; roads break up; large cracks appear in ground; rocks fall

Most buildings destroyed; large landslides; water thrown out of rivers

General panic; damage to foundations; sand and mud bubble from ground

Car steering affected; chimneys fall; branches break; cracksin wet ground

Difficult to stand; plaster,bricks, and tiles fall; large bells ring

People walk unsteadily; windows break; pictures fall off walls

Doors swing; liquid spills from glasses; sleepers awake

Dishes rattle; standing cars rock; trees shake

Shaking felt indoors; hanging objects swing

People at rest upstairs notice shaking

Vibrations are recorded by intruments only



References on the Modified Mercalli Intensity Scale

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