Zhang Heng, a Chinese astronomer, mathematician, engineer, and inventor, made the first seismometer or earthquake detector in AD 132. He lived between 25 and 220 AD during the Han Dynasty.

Zhang is known for developing the world’s first water-powered armillary sphere for astronomical observation and improving the water clock and cataloging over 2,500 stars in a detailed star catalog. He is also credited with inventing the first odometer.

Zhang’s device is about 6 feet in diameter and has eight dragons positioned head down along the outside of the barrel, denoting the primary compass directions. Each dragon has a tiny bronze ball in its mouth. Eight bronze toads stood beneath the dragons, their jaws wide open, ready to accept balls.

One of the spheres will drop when the device detects a coming seismic wave, and the sound will notify onlookers of the quake. It also provides a general estimate of the earthquake’s direction of origin.

The earthquake detector developed by Zhang Heng is believed to be highly accurate. Hundreds of kilometers away, the equipment was able to pinpoint the direction of an earthquake.

Some forms of the sensing system are claimed to be housed inside the seismometer. A primary or inverted pendulum, according to experts, was part of the mechanism.

Experts replicated Zhang’s seismoscope, estimating the content of the inner mechanism by using technology that was available during the great inventor’s time. They utilized the clone to identify earthquakes using waves from four real-world earthquakes in China and Vietnam.

In reality, the data gathered during the experiments is identical to that of modern seismometers.

Seismometers are used to detect and monitor ground movement caused by seismic waves generated by earthquakes, volcanic activity, or a large explosion.

Thousands of these instruments can now be found in strategic locations around the globe. They are constantly monitoring, collecting data, and assisting seismologists in better understanding how earthquakes work. However, they can not predict earthquakes yet.

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