Egypt’s Great Pyramid of Giza built with sophisticated quake resistance
By Will Dunham
May 21 (Reuters) – If ever a structure was built to withstand the test of time, it would surely be the Great Pyramid of Giza, a transcendent monument to human imagination and ambition. Since it was built during the Old Kingdom period of ancient Egypt, it has stood indifferently as time has passed and civilizations have risen and fallen.
Researchers have now discovered one of the reasons for its surprising durability: Since it was built as the tomb of pharaoh Khufu about 4,600 years ago, it was designed and built with structural features that helped it withstand the destructive energy of earthquakes.
Scientists assessed its structural dynamics using devices called seismometers to record ambient vibrations (continuous subtle background shaking created by natural forces and human activities) at 37 points inside and around the pyramid. Despite its size and complexity, it exhibited a very homogeneous and stable structural response to these vibrations.
Located in Giza, just outside Egypt’s capital Cairo, and constructed of massive limestone blocks, each of the four sides of the pyramid measures approximately 755 feet (230 meters) at the base and covers approximately 13 acres (5.3 hectares).
It was originally about 480 feet (147 meters) high. Natural erosion over time and the removal of smooth outer casing stones used as building material centuries ago have left it at its current height of about 455 feet (138.5 meters). It was the tallest structure in the world for approximately 3,800 years.
Scientists have identified various features that ensure the pyramid’s earthquake resistance. It has an extremely wide base, with a low center of gravity, highly symmetrical geometry, gradual mass reduction towards the top, and advanced internal design, including internal baffles that blunt the increase in vibration. It is also built on strong limestone bedrock.
“Together, these elements create a balanced, coherent structure,” said seismologist Mohamed ElGabry of the National Research Institute of Astronomy and Geophysics (NRIAG) in Egypt, lead author of the study published Thursday in the journal Scientific Reports.
“Ancient Egyptian builders clearly had practical knowledge of stability, foundation behavior, mass distribution and load transfer,” said NRIAG seismologist and senior study author Asem Salama.
The researchers found that most vibrations recorded inside the pyramid had a frequency indicating that the mechanical stress was evenly distributed throughout the pyramid.
“So while I would hesitate to claim that they deliberately designed the pyramid specifically for earthquake resistance, I think they naturally developed architectural and geotechnical solutions that produced structures with exceptional long-term durability,” Salama said.
This was learned by trial and error over time, as some flawed pyramids before this one show.
Researchers collected seismic data from various passages and chambers built into the pyramid, including the primary burial chamber, called the King’s Chamber, as well as the surrounding bedrock and soil.
They found that vibration increased as the height inside the pyramid increased, a normal occurrence for tall structures. But despite their higher position, they observed a decrease in amplification in the five private chambers built above the King’s Chamber.
“This shows that these chambers effectively helped dissipate seismic energy and protect one of the most critical areas, the King’s Chamber, from excessive shaking,” ElGabry said.
The most recent earthquakes in the region include those in 1847 and 1992; both severely damaged thousands of buildings, and the last one killed more than 560 people. The pyramid suffered insufficient damage.
It is part of a large complex, along with other pyramids and the Great Sphinx of Giza; All of them have been flooded with visitors since ancient times.
ElGabry said, “The Great Pyramid is not only an extraordinary feat of engineering, but also a profound work of art and human vision. Its perfect symmetry, monumental scale, and graceful proportions create a timeless beauty that continues to amaze even after 4,600 years.” he said.
“What strikes me most, beyond its physical beauty, is the incredible project management and organizational mastery it represents. The construction of such a monument took nearly 20 years and required maintaining a clear, long-term vision, a highly complex supply chain, and the coordination of tens of thousands of skilled workers, engineers, and managers,” ElGabry said. he said.
This will include managing human resources, training a specialist workforce, ensuring a constant supply of food for workers and logistics for large quantities of stone.
“It reminds us of what human civilization can do when vision, science, organization and determination come together,” ElGabry said. he said.
“They really did,” said Salama, “they built ‘one for the ages.'”
(Reporting by Will Dunham in Washington; Editing by Daniel Wallis)
