The modern seismograph was made in 1880. Its principle is basically similar to that of Zhang Heng's seismograph, but the time is late 1700 years. Seismographs have developed rapidly, with various types and high sensitivity, and wireless telemetry and digital recording have been realized.
The first seismic observatory in China was established at 1930 under the auspices of the famous seismologist Li Shanbang, located in Jiu Feng. After more than half a century's struggle, the number of seismic networks in China has grown from one to several hundred, with a national basic network and a rapid earthquake reporting network, all of which can be recorded by seismographs and submitted to the analysis and prediction center of China Seismological Bureau, making China's seismic observation technology at the forefront of the world.
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Structure:
The earliest seismograph in the world was invented by Zhang Heng. The seismograph is made of copper and shaped like a wine bottle. There are eight faucets around. Faucets face east, south, west, north, southeast, southwest, northeast and northwest.
Longkou is movable, and there is a small copper ball in each mouth. Under each tap, there is a copper toad with its mouth wide open. There is a copper pendulum in the center of the instrument, and there are eight channels beside the column, which are called "Eight Classics" and ingenious mechanisms.
Because the seismograph only records the general direction of the earthquake, not the seismic wave, it is equivalent to a seismograph, not a real seismograph. The seismograph invented by Zhang Heng initiated the history of using scientific instruments to predict earthquakes. For a long time, Chinese and foreign scientists have been giving high praise to this. It is considered that it is designed and made by using the principle of inertia, and can detect the main impact direction of seismic waves.
References:
Baidu encyclopedia-seismograph