seismoscope
Quick Summary
A seismoscope is an instrument designed to indicate the occurrence of an earthquake but does not record the time of its occurrence. This is distinct from a seismograph, which records seismic waves caused by earthquakes, explosions, or other ground-shaking phenomena.12
The earliest known seismoscope was invented in 132 CE by Zhang Heng in China. This device featured eight dragon heads with balls in their mouths, which would fall into the mouths of frogs below when an earthquake occurred, indicating that shaking had happened.2
Modern seismographs, in contrast, translate ground motions into electrical signals that are then recorded. These instruments are crucial for understanding earthquakes and have various applications, including petroleum exploration and monitoring volcanic activity.23
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