TheGreat Pyramid of Khufu has faced earthquakes, desert storms, and centuries of erosion, yet it still stands. A new study suggests that part of its resilience may come from an unexpected advantage. The researchers found that the monument vibrates at a different frequency than the ground beneath it.
The Great Pyramid was built during Egypt’s Old Kingdom using limestone blocksweighing around 2.5 tons each. For generations, historians and archaeologists have been fascinated by how such a massive structure was constructed. Now, scientists are taking a closer look at another question: how it has managed to remain standing for so long?
To find out, a team led by seismologist Asem Salema from Egypt’s National Research Institute of Astronomy and Geophysics (NRIAG) studied how vibrations move through the monument. According to Scientific Reports, the goal was to understand whether the pyramid’s structure offers any protection against earthquake damage.
The Great Pyramid Doesn’t Move With the Ground
One of the key concepts behind the study is resonance. This happens when a structure vibrates at the same frequency as the forces acting on it, which can dramatically increase movement and stress during an earthquake.
To investigate, the researchers installed 37 sensors in and around the pyramid. As explained in the paper, they used a technique called horizontal-to-vertical spectral ratio analysis (HVSR) to record tiny vibrations in different parts of the monument and in the surrounding ground.
The results showed that the pyramid and the ground beneath it do not share the same natural frequency. This difference makes the structure less likely to absorblarge amounts of seismic energy through resonance.
A Structure Built to Survive Earthquakes?
The study recalled that the Great Pyramid has already experienced significant seismic events over its long history. One example is the 1992 Cairo earthquake, which reached a magnitude of 5.9.
Despite the shaking, the pyramid suffered only minimal damage. The new research does not claim that resonance alone explains this outcome, though it suggests that the frequency mismatch may have contributed to the monument’s ability to withstand such events.
Resonance has been linked to the failure of structures in many parts of the world. In the case of Khufu’s pyramid, the researchers found evidence that the monument responds differently from the ground on which it stands.
Design Features That May Help Absorb Vibrations
The team also looked atseveral architectural characteristics of the pyramid. Its shape naturally concentrates most of its mass near the base, while its symmetry helps distribute weight evenly.
In their study published in Scientific Reports, the researchers found that the chambers located above the King’s Chamber may also play a role by relieving pressure generated by seismic responses higher in the structure. The limestone used in the monument and the underlying bedrock appears to help dissipate vibrations as they travel upward.
They see these features as contributing factors to the pyramid’s long-term stability. Still, they are careful not to go further than the evidence allows. Salema noted that any idea that ancient Egyptian builders deliberately designed the monument to resist earthquakes remains speculative and cannot be confirmed by geophysical measurements alone.
“These findings present compelling quantitative evidence that ancient Egyptian architects possessed profound geotechnical understanding, optimizing structure design and site characterization to assure millennial-scale stability against seismic hazards,” as the authors said.
