Machu Picchu Withstood Powerful Earthquakes

Machu Picchu is earthquake resistant because Inca builders used ashlar masonry, cutting stone blocks to fit tightly together without mortar. During an earthquake, the joints allow the stones to move slightly before settling back into their original positions instead of forcing the wall to crack. A magnitude 6.5 or stronger earthquake struck during the site's construction around 1450, loosening blocks in the Temple of the Sun and damaging other ceremonial structures. Afterward, the Inca improved their seismic engineering with massive foundation stones, narrower inward-sloping upper walls, and trapezoidal structures that remain standing across the Cusco region.

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