Secrets of the Great Pyramid: Scientists uncover hidden structures

The Great Pyramid has endured earthquakes for about 4,600 years despite tremors up to magnitude 6.8. Researchers found no major internal or external deterioration. The structure’s resistance is linked to building on hard limestone bedrock, using a symmetrical pyramid shape, maintaining a rigid overall design, and adding pressure-relieving cavities above the King’s Chamber. Vibration measurements were taken at 37 locations, including internal chambers, construction blocks, and surrounding soil. Most vibrations inside the pyramid occurred at 2.0 to 2.6 hertz, while surrounding soil vibrations occurred at about 0.6 hertz. The frequency mismatch reduces earthquake damage by avoiding resonance between ground motion and the pyramid’s natural response.

"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. Now, 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.'"

"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"

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