The Ancient Seismograph:
The Ancient Seismograph:
Saving Lives and Furthering Science
Saving Lives and Furthering Science
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What Is A Seismograph?
What Is A Seismograph?
A seismograph is a machine that observes earthquakes and their magnitude. In 132 AD, behind the walls of the Chinese city of Sain, a talented scientist called Zhang Heng created the world’s first seismograph. (Sleeswyk & Sivin 2)
THEN
THEN
Figure 1: A model of Zhang Heng's ancient seismograph.
NOW
NOW
Figure 2: Present-day seismograph.
Why Was It Needed?
Why Was It Needed?
Violent earthquakes have been plaguing the eastern hemisphere for centuries. In ancient times, not only did earthquakes cause physical damage to China, but were followed by riots, rebellion, and death. The Chinese people wanted a way to get ahead of these natural disasters, and there came the seismograph. (Seismology in Ancient China)
Figure 3: Aftermath of the Sichuan earthquake of 2008.
Figure 4: Zhang Heng, the creator of the seismograph.
Figure 5: A model of the inside of the seismograph.
How did it work?
How did it work?
The seismograph of 132 AD is thought to be a very complex device. The machine's given name "Hou Feng Di Dong Yi", mostly consisted of a large bronze pot decorated with animals, writing, and mountains. 8 dragons surrounded the top of the pot and 8 toads with open mouths sat directly under them. There were 8 of each for the reason that they corresponded with one of the directions of a compass.
Inside each dragon's mouth was a metal ball. When an earthquake struck, the ball would fall into the toad's mouth sitting under it, causing a loud, alarming sound. Whichever direction the metal animals were facing was where the earthquake was coming from.
The inner workings of this early seismograph are still a mystery today, but that didn’t stop scientists from trying to solve it. Many models have been constructed by modern scientists, as shown to the left. (Yan & Hsiao)
Impact on Ancient China
Impact on Ancient China
Figure 6: With China now having a device that lets them accurately predict the direction and timing of earthquakes, it allowed the people to prepare. Reinforcements could arrive on time and try to control the situation.
Impact On Other Civilizations
Impact On Other Civilizations
Figure 7: Zhang Heng’s invention was lost for a millennium and wasn’t rediscovered until the 1700s. Not knowing how it truly worked hinders how much scientists today can learn from this technology, but it has still been a basis and example for seismic devices today. (Seismology in Ancient China)
What Made the Seismograph So Historically Important?
The seismograph was a very impactful invention for its time. It allowed people to prepare properly for the natural disasters that heavily affected their society. Without it, many Chinese cities could have been left in rubble and destruction.
Want to Learn More About the Mysterious Seismograph? Try These Other Websites!
"Ancient Seismometer"
"Ancient Seismometer"
Figure 8: Scientists take on the challenge of reconstructing the seismoscope and explain how it works.
"Seismograph"
"Seismograph"
Figure 9: Learn how seismographs were constructed all around the world throughout history.
"How are Earthquakes Recorded?"
"How are Earthquakes Recorded?"
Figure 10: The United States Geological Survey explains how earthquakes are measured and how seismic devices work.
"The First Seismoscope"
"The First Seismoscope"
Figure 11: A video providing a breif history and showing visual representation on how Zhang Heng's invention was thought to work.
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