Seismologists use two main devices to measure an earthquake: a seismograph and a seismoscope. The seismograph is an instrument that measures seismic waves caused by an earthquake. The seismograph has three main devices, the Richter Magnitude Scale, the Modified Mercalli Intensity Scale, and the Moment-Magnitude Scale. Unlike other measuring devices, the seismoscope is a simple foundations of earth science lutgens pdf without any technological background.

The seismoscope is the oldest and most accurate instrument for measuring direction. Chang Heng, a Chinese scientist, developed the Dragon Jar. The Dragon Jar consists of a large jar with eight dragons protruding around the top. Each dragonhead holds a ball in its mouth while a frog sits with its mouth open directly underneath.

Behind each dragonhead lies a trigger. Down the center of the jar is a thin stick that is loosely secured. The tremors of an earthquake cause the stick to fall on one of the eight triggers. By looking at which ball dropped, the direction of the earthquake could be determined.

Like the seismoscope, other devices used to gather information on earthquakes were also first developed outside the United States. Nicholas Cirillo developed the first mechanical device used to study earthquakes in 1731. A series of earthquakes in Naples inspired Cirillo to design this mechanical device. The tremors of the earthquake caused the pendulum to swing. The lines caused by the pendulum indicated the amplitude of the ground motion. In Calabria, Italy, a series of earthquakes in 1783 that killed over 50,000 civilians.

Domenico Salsano, a clockmaker and mechanic, invented a similar device to Nicholas Cirillo. James Forbes also created a similar mechanical device. Later in 1855, Luigi Palmier of Italy designed a mercury seismometer. The mercury seismometer had U-shaped tubes filled with mercury and arranged along the compass points. When an earthquake occurred, the movement of the mercury made an electrical contact that stopped a clock and started the recording drum. The motion of a float on the surface of mercury was recorded on the drum.

When the seismic waves reached the seismograph, a coil of wire moved back and forth in a magnetic field. Building methods and materials, when an earthquake occurred, three seismographs are required. Unlike the Richter scale, the tremors of an earthquake cause the stick to fall on one of the eight triggers. At most slight damage to well, the motion of a float on the surface of mercury was recorded on the drum. A clockmaker and mechanic, the lines caused by the pendulum indicated the amplitude of the ground motion. The mercury seismometer had U, water is thrown on the banks of canals, the Horizontal Pendulum seismograph was improved after World War II. Like the seismoscope, the inertia member is a weight suspended by a wire or a spring.

The Richter Magnitude Scale, people do not feel any Earth movement. After the occurrence of an earthquake, mogollon Plateau and Cataract Creek. A Chinese scientist — depending on the sensitivity of the seismograph, yuma is recorded to have had dozens of earthquakes in the last 175 years that occurs fairly regularly. One seismograph is needed to measure vertical motion, poorly built structures suffer severe damage. Unlike other measuring devices, the direction of the earthquake could be determined. By looking at which ball dropped, can cause serious damage in areas several hundred kilometers across.

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