Mega Earthquake Caused Major Shift in Inca Construction Methodology
A major new scientific study revealed by Peru’s state-run news agency Andina has confirmed that construction of the ancient Inca city, Machu Picchu, located in modern day Peru, was interrupted in 1450 AD by a 'powerful earthquake’ that caused the Inca builders to design catastrophe-resistant architecture.
What Was the Strength of The Violent Earthquake?
On the other side of the world in 1450 AD Johannes Gutenburg began operating the first mechanical printing press and the mysterious Voynich manuscript was brought to completion, but in ancient Peru, the mountains shook under the force of a violent earthquake. According to an article in The Peruvian Times, researchers from the Cusco-Pata Research Project have announced that the ancient landscape was hit by “a tremor of at least magnitude 6.5” during the reign of the 9th Inca Pachacútec.
Earthquake recorded in about 1450 AD caused the separation of rocks in Machu Picchu. (Andina)
Shift in the Earth Brings Forth Shift in Construction
Evidence of the earthquake has been gathered by an international team of scientists since 2016, led by the Geological, Mining, and Metallurgical Institute (Ingemmet), and project coordinator Carlos Benavente Escobar. Escobar told reporters, “There was already construction underway with one type of architecture under Pachacutec. Then, we believe, in the middle of that construction of Machu Picchu there was a major earthquake.” Machu Picchu was the iconic mountain top summer estate of the 9th Inca ruler (Sapa) Pachacutec.
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Sample of seismic-resistant architecture (trapezoidal): Sacsayhuamán Archaeological Park. (Andina)
How Was the Damage Evident?
It was “openings between rocks and stones” which acted as clues as the scientists knew such miss-alignments were “not typical of the Incas because they employed an impeccable, perfect construction.” The earthquake damage is most prevalent in the walls of the “Temple of the Sun” at Machu Picchu where Benavente said, “Some edges of the rocks are broken, which means that in the undulation of the earth, they hit each other which caused the breaks. After that, they continued the building in a different manner to complete what would become Machu Picchu.”
In the Sacsayhuamán Archaeological Park, there is also a separation between rocks produced by an earthquake of 1450. (Andina)
How Did the Incas Change Their Construction Methods?
An article in Porta Andeana explains that “After these deformations” caused by the earthquake, Pachacútec, having seen the underlying weakness in his current construction methodology, “arranged a modern architecture and placed masonry to repair the damage caused by the earthquake.” And the scientists also noted “Architectural change in the [agricultural] terraces.”
After the quake, the Incas began building in what is being described as “a more rustic cellular architecture and continued to develop and perfect seismic-resistant trapezoidal structures, with giant stone blocks at the base with narrower upper walls.” Benavente concluded that “They knew how to coexist with diverse geologic dangers, like earthquakes, landslides, and avalanches.”
Sample of cellular architecture: Piquillacta Archaeological Complex. (Andina)
How Can the Study of the Quake that Changed Inca Architecture Help Us Today?
Aiming to establish the geological origins of the earthquake that had such an impact on the Inca Empire, Benavente said “We are calibrating the last 14 radiocarbon ages to define what failure caused the earthquake, for the moment, it is suspected that it was the one in Tambomachay, located four kilometers from the Historic Center of Cusco.” “There is no doubt,” he says, “that the strong earthquake also caused the deformation of the walls of Sacsayhuamán, Tipón, and Tambomachay.”
Fieldwork at the Choquepuquio Archaeological Center. (Andina)
“For the first time in history, the techniques of paleoseismology, archaeo-seismology, and active tectonics have been combined in a study of this nature,” Benavente said. And he thinks it “necessary to help current-day planners analyze the seismic hazards of the Tambomachay and Pachatusan fault lines for the Cusco region.”
Separation of rocks in Machu Picchu due to an earthquake of at least magnitude 6.5, registered in approximately 1450 AD. (Andina)
What Has the Research Discovered?
In July this year Dr. Ken Tokeshi from Western Sydney University published a research paper, Earthquake risk to Inca's historical constructions in Machupicchu, presenting his “seismic risk analysis of the heritage structures at Machupicchu, identifying of the probable mode of failure of the structures concerned.” Like in this latest study, Dr. Tokeshi studied the “Results of the microtremor measurements to estimate the dynamic characteristics of the Inca stone structures.”
How Was the Affected Structure Used?
While it is clear that Cuzco was the ancient capital city of the Inca Empire, the function of the structure at the suspected heart of the earthquake, ‘Tambomachay,’ remains something of a mystery. Consisting of elaborate stone-built canals and waterfalls running through the rock terraces, some archaeologists believe it might have been a military outpost guarding the primary approaches to Cusco, but others think it was a spa retreat for the social, political, and religious elite from Cuzco.
Tesista Lorena Rosell in the Sacsayhuamán Archaeological Park. (Andina)
Top Image: Note the separation between rocks in the Sacsayhuamán Archaeological Park. Source: (Andina)
By Ashley Cowie