Great Pyramid of Giza is remarkably resilient to earthquakes — and it’s due to the ancient Egyptians’ ‘extraordinary’ engineering knowledge
Egypt Great Pyramid of Gizaalso known as the Great Pyramid of Cheops, has stood for more than 4,600 years, despite powerful earthquakes. Now, new research explains why: the structure is remarkably resistant to vibrations.
The pyramid has only lost about 10 meters in height since its construction during the Old Kingdom of Egypt (2649 to 2150 BC). And this despite extensive experience earthquakes over the millennia, including one with a magnitude estimated at 6.8 which struck south of Cairo in the town of Fayoum in 1847 and an earthquake of magnitude of 5.9 in 1992 which caused some of the taller stones to fall to the ground.
“[T]“The study highlights the extraordinary practical engineering knowledge of ancient Egyptian builders, who developed highly efficient construction practices over centuries of experimentation and refinement,” said the study co-author. Asem Salamageoscientist at the National Research Institute of Astronomy and Geophysics in Cairo, Live Science wrote in an email.
Salama and his team placed vibration sensors at 37 sites in and around the Great Pyramid and recorded ambient vibrations when no tourists were inside the pyramid. “In heritage conservation, this information can provide important insights into structural stability, hidden vulnerabilities and long-term preservation strategies while fully respecting the integrity of the monument,” explained Salama.
The layout of the Great Pyramid included many rooms and corridors.
(Image credit: Asem Salama et al./Scientific Reports)
The team found that throughout the pyramid, the vibrations were remarkably similar, ranging from about 2.0 to 2.6 hertz. This was quite different from nearby ground frequencies, which were typically around 0.6 hertz. This difference in frequency means that during earthquakes, the pyramid is away from vibrations passing through the ground, perhaps contributing to its resilience, the researchers reported Thursday (May 21) in the journal Scientific reports.
An archaeologist takes measurements inside the relief chambers of the Great Pyramid of Giza in Egypt. The inscription on the left side commemorates the discovery of the upper four chambers by Western archaeologists in 1837.
(Image credit: Asem Salama et al./Scientific Reports)
Other features contributing to the pyramid’s stability include its massive base, strong limestone foundations and symmetrical geometry, Salama said. Vibrations increase toward the top of the structure, which is typical in most buildings (imagine a skyscraper built to sway during an earthquake), but this pattern is interrupted by the decompression chambers located about 200 feet (61 m) high inside the pyramid. These rooms are located above the King’s Chamber and are said to have been built to alleviate some of the weight of the pharaoh’s final resting place. They also appear to dampen vibrations that might otherwise propagate toward the top of the structure.
Archaeologists take measurements in the passage coming from the entrance to Caliph al-Ma’mun (also known as the Thieves’ Tunnel).
(Image credit: Asem Salama et al.)
The researchers plan to take more measurements on the Great Pyramid and hope to use similar methods at other important Egyptian archaeological sites. It is likely that some of the characteristics of the pyramid shape help to protect the other pyramids at Giza, but each structure is likely unique, Salama said, as Ancient Egyptian architects have evolved their methods over time.
“Earlier pyramids,” he said, “show evidence of experimentation and structural evolution, including changes in slope geometry and internal layout.”
Are you a fan of mummies and hieroglyphics? Find out with our Quiz on ancient Egypt!
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