Archaeologists have uncovered one of the Great Pyramid's secrets – revealing how the ancient tomb has managed to withstand earthquakes for 4,600 years. Since it was built, the magnificent structure has experienced significant tremors with magnitudes of up to 6.8. Earthquakes of this size are capable of causing significant damage to buildings within 155 miles (250km) of their epicentre. However, the Great Pyramid, built for Egyptian Pharaoh Khufu, has suffered no major deterioration internally or externally.
Remarkable Engineering Techniques
Experts have finally worked out why – and it's all thanks to remarkable engineering techniques that the ancient Egyptians used. This included building the structure on hard limestone bedrock, a symmetrical pyramid shape, a rigid overall design, and creating pressure-relieving cavities above the King's Chamber. 'These findings present compelling quantitative evidence that ancient Egyptian architects possessed profound geotechnical understanding,' the team, from the National Research Institute of Astronomy and Geophysics, said. 'The pyramid is distinguished by certain geometric aspects and features from an engineering point of view that make it one of the best designs resistant to earthquakes.'
Study Findings
For their study, published in the journal Scientific Reports, the researchers recorded vibrations at 37 locations around the pyramid. This included in its internal chambers, construction blocks, and in the surrounding soil. They discovered that most vibrations recorded within the pyramid had a frequency of 2.0 – 2.6 hertz, which indicates mechanical stress is evenly distributed throughout the structure. On the other hand, vibrations in the surrounding soil had a frequency of 0.6 hertz. This difference is important because earthquake damage becomes much worse when the ground and structure vibrate at similar frequencies. Since the pyramid's natural response is to vibrate at much 'faster' and 'stiffer' frequencies compared to the slower swaying of the ground, it means seismic energy from the ground is not efficiently transferred into the structure.
Vibrations and Structural Protection
The team also discovered that vibrations are amplified higher up the pyramid, peaking in the King's Chamber. However, in the cavity directly above the King's Chamber, the vibrations appeared decreased – indicating it was put there to provide some kind of structural protection to the sacred tomb. 'This result is consistent with the idea that the design of these rooms contributes to diminishing the stresses on the King's Chamber,' the researchers wrote. The team believe the geometry of these five chambers helps to dissipate or redirect stress during shaking. The ancient Egyptians also built this pyramid on hard limestone, which can help to increase resistance to tremors. The structure is also designed to have a wide base and low centre of mass, making it stable and resistant to toppling during shaking.
Ancient Engineering Mastery
While it's impossible to say that the builders understood seismic physics, the researchers argue their geometry and engineering were extraordinarily advanced. These ancient Egyptians achieved structural designs that modern earthquake engineering recognises as highly effective. 'The observed frequency separation between soil (0.6 Hz) and pyramid structure (2.3 Hz) indicates naturally reduced resonance risk, which may contribute to the monument's remarkable seismic endurance over millennia,' the archaeologists concluded. But they added: 'Any suggestion of intentional seismic optimisation by ancient Egyptian architects remains purely speculative.'
Additional Research
A separate study, published earlier this year, suggests the Great Pyramid was built using a hidden spiral ramp running inside the structure. Computer scientist Vicente Luis Rosell Roig believes workers used an 'edge ramp' – a sloping path along the pyramid's outer edges that was gradually covered as each new layer was added. Instead of relying on massive external ramps, this would have allowed workers to move stones steadily upward, one level at a time. Simulations suggest blocks could have been placed every four to six minutes – a fast, consistent pace. At that rate, the pyramid could have been completed in just 14 to 21 years. When quarrying, transport, and breaks for workers are factored in, the total timeline rises to around 20 to 27 years, in line with existing estimates.
