In modern times, we have technology for just about anything. One of the greatest – often life-saving inventions of modern times is the seismograph, the instrument used to help us determine where earthquakes are going to occur and how disastrous they are going to be. Although our current technology isn’t as precise as we would like, it is much more adequate than its predecessors. These ancient, and I mean ancient, inventions date back about 2,000 years ago with the first seismograph being created by Chinese inventor Zhang Heng. Even back then people knew how cataclysmic an earthquake could be, and they did everything to avoid them as well.

The Ancient Chinese Earthquake Detector

Ancient Chinese weren’t aware of the fact that earthquakes were caused by friction on the edges of tectonic plates or by volcanic processes. They explained the phenomenon as riots between the cosmic energies of yin and yang. Because it was important to keep the energies balanced, rulers saw it necessary to be able to predict earthquakes before they happened.

In 132 AD, Zhang Heng created this premier seismograph. This ancient invention is still very precise, even when pinned against today’s technology. Zhang Heng’s device was so accurate that it could detect earthquakes from great distances which was something that was appreciated by the imperial court.

The device was six feet in diameter, with eight dragon heads arranged around the rim, each facing one of the eight directions. Each one of the dragons had a bronze sphere in their mouth. Around the feet of the dragons Zhang Heng placed several bronze frogs with their mouths open. If the device registered an earthquake one of the bronze spheres would automatically loosen and fall in the mouth of the frogs. The position of the frogs indicated the direction where the Earthquake occurred. The seismograph was able to detect earthquakes up to 400 miles away, however the data was not always decisive.

How The Seismograph Has Evolved


The invention of the seismograph opened up the path to saving millions of lives and understanding more about the natural phenomenon known as earthquakes in modern times. Many components of the original invention, such as the idea of a slight imbalance helping determine distance and degree of an earthquake, have been reimagined to create the machinery we use today. We have gone from using dragons and toads to using the cylindrical paper roll we are all more familiar with. The needle on the roll has replaced the ball from the dragons’ mouths, but none of this would’ve been possible without the original ideas and uses of the first seismograph centuries ago.

Although we are still unable to predict with accuracy when and where an earthquake will happen, we have made significant advances in the detection, recording, and measurement of seismic waves. One day we will be able to predict earthquakes more accurately than ever before. Thanks to Ancient Rulers of China, and Zhang Heng, we were given the groundwork we needed to build from.




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