The Cheops Pyramid is not only a miracle of ancient Egyptian architecture, it is also surprisingly stable: the 4,500-year-old structure has even survived strong earthquakes without damage. Geophysicists have now determined why this is so. Accordingly, the secret lies in the internal structure of the pyramid. It is built in such a way that it distributes mechanical loads particularly evenly, and its resonance frequency also differs significantly from that of the subsurface. This prevents the vibrations from escalating during an earthquake.
Built 4,500 years ago, the Great Pyramid of Giza is one of the largest man-made structures. Together with its two neighboring pyramids, this royal tomb was already considered one of the seven wonders of the world in ancient times. No wonder: the Great Pyramid weighs more than six million tons, contains more than 2.3 million stone blocks and is around 139 meters high. How the ancient Egyptians managed to build such a complex and monumental structure using the simplest means is still only partially understood today.
A special feature of the Great Pyramid is its enormous stability: it has survived more than 4,500 years almost undamaged; only a few stone slabs of its cladding have fallen off since it was built. This is particularly remarkable because the pyramids of Giza have also survived several earthquakes. The strongest earthquake measured had a magnitude of 6.8 and occurred in August 1847, only around 70 kilometers away. In 1992, an earthquake with a magnitude of 5.8 shook the structure. However, none of these earthquakes caused major damage to the Great Pyramid.
It depends on the frequencies
But what gives this millennia-old structure its great stability? A factor that has been known for a long time is the shape of the pyramid: “Most of the mass is concentrated close to the ground and then gradually decreases towards the top,” explain Mohamed ELGabry from the National Research Center for Astronomy and Geophysics in Cairo and his colleagues. This ensures a low center of gravity. The solid, symmetrical construction and the wide base provide additional stability.
But that’s not all, as ELGabry and his team have discovered. “One of the main parameters that determine the dynamic response of a structure is the interaction between the intrinsic frequencies within the structure and those of the surrounding subsoil,” explain the researchers. In concrete terms, this means: the more similar the natural vibrations of the structure and the subsoil are, the easier it is for an earthquake to hit the resonance frequency of the structure. As a result, the vibrations build up and can cause serious damage.
Vibration measurements in the Great Pyramid
The researchers have now examined in more detail what these vibration frequencies look like in the Cheops pyramid. To do this, they placed highly sensitive accelerometers and seismometers at 37 locations inside and outside the pyramid. They installed twelve measuring devices in the royal burial chamber and the corridor leading to it alone, seven in the queen’s chamber and more in underground corridors and in the relief chambers above the king’s chamber.
The measuring instruments recorded the weak vibrations that occur independently of stronger earthquakes – for example from construction activities, trucks and cars driving nearby, but also from sea waves or weather influences. From this data, the team determined the characteristic natural vibration of the subsoil and various parts of the pyramid, but also how strongly external vibrations are amplified by the structure.
Different vibration frequency than the ground
The measurements provided insightful insights into the stability secret of the Great Pyramid. They revealed that the natural vibrations of various parts of the structure differ significantly from those of the subsoil. “The majority of the measurements revealed a fundamental oscillation frequency between 2.0 and 2.6 Hertz, with the average being 2.3 Hertz,” report ELGabry and his colleagues. “In contrast, the predominant frequency in the surrounding subsurface of the Giza Plateau is 0.6 hertz.”
According to the researchers, these significantly different natural oscillation frequencies provide an additional explanation for why the Great Pyramid survived even more severe earthquakes largely unscathed. Their measurements also showed that the internal structure of the pyramid dissipates and distributes mechanical loads particularly evenly. This means that earthquakes do not create zones with particularly strong pressure on the material.
Relief construction additionally protects the king’s chamber
The Egyptian builders also used another technique to protect the pharaoh’s burial chamber from damage: the relief chambers. They are formed by five massive granite beams placed one above the other, leaving small cavities between them. This construction serves to divert the weight of the stone masses in such a way that the King’s Chamber and the Great Gallery leading to it are relieved.
As can now be seen, the relief chambers also contribute to resistance to earthquakes. The measurements showed that vibrations at ground level increase with increasing altitude. At the level of the royal burial chamber the amplification factor is 4.0, but the relief chambers above reduce it again to a factor of 3, as ELGabry and his team determined. “This is consistent with the idea that the design of these chambers helps to reduce stresses on the royal chamber,” they explain.
Source: Mohamed ELGabry (National Research Institute of Astronomy and Geophysics (NRIAG), Cairo) et al., Scientific Reports, 2026; doi: 10.1038/s41598-026-49962-6