Azernews.Az

By Alimat Aliyeva

An international team of geophysicists has explained why the Pyramid of Khufu (Cheops) has survived thousands of years of seismic activity with almost no structural damage. According to the researchers, the key factors are the difference in vibration frequencies between the pyramid and the surrounding soil, the monument’s geometric shape, and the system of internal “relieving chambers” above the pharaoh’s burial chamber, AzerNEWS reports.

“All of this is extraordinary from the perspective of modern engineering. But it becomes even more remarkable when we consider the tools and resources available 4,600 years ago,” said Mohamed El-Gabri, lead author of the study and geophysicist at the National Research Institute of Astronomy and Geophysics in Cairo.

To avoid damaging the ancient structure, the scientists did not use artificial vibration sources. Instead, they installed highly sensitive accelerometers at 37 points inside and around the pyramid, measuring natural background vibrations caused by ocean waves, traffic, and everyday human activity.

Measurements showed that at roughly three-quarters of the points inside the structure, the pyramid naturally resonates at frequencies between 2 and 2.6 Hz. This narrow range suggests a highly uniform distribution of weight throughout the structure. In contrast, the surrounding soil vibrates much more slowly, at around 0.6 Hz.

This difference prevents resonance: the pyramid does not amplify ground vibrations, which would otherwise severely threaten its stability. The effect is similar to modern seismic isolation systems, but achieved entirely through ancient architectural design.

Additional protection comes from the relieving chambers built above the burial chamber, which distribute the immense weight of the stone blocks and help dampen vibrations as they move upward through the structure.

Interestingly, like an inverted pendulum, most tall structures experience stronger vibrations at higher levels. In the pyramid, vibration amplitude increases about fourfold in the burial chamber, but only about threefold in the chambers above it — a pattern that researchers still cannot fully explain.

What makes this even more fascinating is that some engineers now believe the Great Pyramid may have been unintentionally designed with a form of “natural vibration filtering,” a principle that modern skyscraper designers are only beginning to fully understand and replicate using advanced materials and dampers.