Who invented seismograph for detection of earthquake and measurement of its intensity?

Earthquakes have been a significant part of the history of our planet. Throughout history, humans experienced several earthquakes that shook the Earth. The creation of new lands, separation of landmasses, formation of mountains, and many others are all related to earthquakes. Most of us probably know brief information about how they occur, and it is mainly due to the movement of the Earth’s tectonic plates. 

On the other hand, however, earthquakes are devastating to humans. And sometimes, the problem is not only in the earthquake itself but also in the deadly chain of reactions it brings. An earthquake that is powerful enough could cause a tsunami hitting the coast and nearby cities. It could also lead to the destruction of various structures, including buildings, houses, bridges, power stations, and many others, which could sometimes result in fire. Records show that the average earthquake damage could sum up to millions or billions of US dollars. As deadly as it seems, strong earthquakes often result in thousands of fatalities and leaving several more families homeless.

With all these said, the destructive power of an earthquake is evident, and there is no way to stop it. The best that we can do is prepare for it. 

Even with the advanced technology we have today, there is no way to precisely predict an earthquake. However, scientists developed a way to detect them, which helps to study the internal structures of the Earth further. The process of detecting earthquakes is possible with the help of an instrument called a seismograph. The use of seismographs is mainly for detecting the location of an earthquake, as well as its intensity.

The History of Seismograph

The very first type of seismograph was invented in China thousands of years ago by Chinese scientist Zhang Heng. The appearance of ancient seismographs, initially known as the dragon jar, is far different from what we have today. 

The dragon jar was a bronze cylinder covered with ornaments on its outer surface. The decorations include antique seal characters and designs such as mountains, tortoise, birds, and animals. Surrounding the outer layer of the jar were eight dragon heads, wherein each head is holding a bronze ball in its mouth. At the bottom, eight frogs were lying directly below each dragon head with their mouths opened. The purpose of the frogs is to catch the ball that the dragons might drop. 

The dragon jar consists of a delicately balanced column inside the vessel. This column was what operates the mechanism inside the jar every time there was an earthquake. The device was like a pendulum, which moves along one of eight directional tracks. When there was an earthquake, the column would rock inside and operates the mechanism, which would cause the dragon to drop the ball from its mouth. The toad would then catch the dropped ball, and through this, the direction of the earthquake could be determined by which toad catches the ball. When the ball dropped, it creates a loud noise to alert the observers about the earthquake. 

Early accounts of the use of dragon jars included one event when a dragon head dropped the ball from its mouth. This activity baffled the observers since there is no earthquake felt at that time. However, several days later, a messenger from the east arrived, bringing news of an earthquake 700 kilometers away. 

Since then, the use of seismographs became familiar to scientists and researchers. Different scientists and inventors created their version of the seismograph until such time it was perfected. 

We can attribute the invention of the first modern design of the seismograph to the English seismologist and geologist, John Milne. Apart from inventing the modern seismograph, John Milne, along with his co-scientists James Alfred Ewing and Thomas Gray, promoted the founding of seismological stations. 

The three British scientists used to work as foreign-government advisors in Japan from 1880 to 1895. During their term in Japan, they began to study earthquakes and founded the Seismological Society of Japan, which focused on the creation of seismographs. In the same year, John Milne invented the horizontal seismograph. 

After World War II, they improved the horizontal seismograph and resulted in the Press-Ewing seismometer.

Additional reading:

Seismometer (Wikipedia)
Zhang Heng (Wikipedia)

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