Researchers from various nations have uncovered the reason why the renowned Egyptian edifice has withstood millennia of seismic activity with minimal damage. The primary explanation lies in the disparity between the building’s vibration frequency and that of the surrounding earth. Furthermore, the structure’s form and the design of specialized chambers situated above the pharaoh’s burial site play a significant role.
“All of this is remarkable from a contemporary engineering perspective. However, it is even more astonishing when considering the tools and resources available 4,600 years ago,” stated the head of the scientific project, Mohamed El-Gahry.
To preserve the integrity of the historical monument, the researchers opted against employing artificial vibration sources. Instead, they deployed 37 high-sensitivity sensors both within and on the exterior of the structure. These instruments recorded natural oscillations stemming from traffic, human activities, and even distant ocean waves.
At nearly 75 percent of the measurement points inside the building, vibrations occurred within a frequency range of 2 to 2.6 Hertz. This narrow spread in readings, as reported by the publication Izvestia, indicates that the immense weight of the structure is distributed with remarkable uniformity. In contrast, the ground in the vicinity vibrated much more slowly, at a frequency of approximately 0.6 Hertz.
This frequency difference prevents the onset of destructive resonance. The building does not absorb the energy of seismic shocks, which could otherwise significantly compromise its structural integrity. This phenomenon closely resembles modern earthquake protection systems, yet it was accomplished in antiquity without the use of technologies familiar to us today.
Additionally, the monument is protected by what are known as relieving chambers, constructed to evenly distribute the colossal weight. Measurements have demonstrated that these chambers effectively dampen vibrations as they travel towards the top of the structure.
Most conventional buildings experience the most pronounced swaying in their upper sections, akin to an inverted pendulum. In the Egyptian edifice, the amplitude of oscillations in the lower chambers amplifies by a factor of four, but in the chambers higher up, it increases by only three times. The exact mechanism behind this protective effect is a subject that scientists are still in the process of thoroughly investigating.
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