Ancient Engineers Made Great Pyramid Quake-Proof

Earthquakes have rattled Egypt for millennia, but one structure keeps shrugging them off: the Great Pyramid of Giza. A new study says that's no accident, crediting the 4,600-year-old monument's design with keeping it unusually steady when the ground moves, reports Live Science. For their study in Scientific Reports, researchers placed vibration sensors at 37 spots in and around the pyramid, then measured how it naturally "shakes."

They found that the pyramid mostly vibrates at higher frequencies (about 2.0 to 2.6 hertz) than the surrounding ground (around 0.6 hertz), effectively decoupling it from many seismic waves. Contributing to that resilience: the pyramid's broad base, robust limestone foundation, and precise symmetry. Inside, a stack of so-called pressure-relieving chambers above the "King's Chamber" appears to interrupt and dampen vibrations as they move upward.

"Ancient Egyptian builders clearly possessed practical knowledge related to stability, foundation behavior, mass distribution, and load transfer," says senior author Asem Salama of the National Research Institute of Astronomy and Geophysics in Egypt, per Reuters. The findings help explain how the structure has lost only about 33 feet of height despite multiple strong quakes—and could offer insights to modern builders.