The Spanish-Mexican study reveals the reasons that led the population of this impressive city with pyramids to flee to safer places in the year 650. Experts agree that it went from housing more than 100,000 inhabitants in the 2nd century to just under 5,000 in the 7th.
Five major seismic movements occurred approximately between the years 100 and 650. They destroyed or seriously damaged its main buildings and directly led to the collapse of this civilization, despite the desperate efforts of its inhabitants to try to rebuild what nature denied them. The possibility that the megaearthquakes of the Mesoamerican Trench could be responsible for the damage does not conflict with other existing theories about its collapse, considering that the sudden superposition of natural disasters such as earthquakes could increase internal wars, the uprisings, and civil unrest, indicates the article signed by specialists from the Geological and Mining Institute of Spain and the universities of Barcelona, Salamanca, the Autonomous of Madrid, Politécnica, and Michoacana. Spanish and Mexican specialists believe that the megaearthquakes that destroyed the city originated in the so-called Mesoamerican Trench in the Pacific Ocean. The EAEs described include broken and fragile corners affecting the western stairs of the Pyramid of the Sun and the new and old temples of the Feathered Serpent. They completely rule out, and based on scientific evidence, that this damage could be due to deliberate human breakage or climatic erosion of the basalt stones of the stairs. “The conjugated action of ancient tectonic movements can explain the archaeoseismic damage documented in some places, but the two are the most probable cause, the experts say. The combination of the high seismic energy released by repetitive earthquakes is the most likely cause of the damage to the pyramids and the temples, they say. They admit, the earthquakes could have had another origin, a place close to the city, although they consider it less likely. The city suffered "at least two strong destructive earthquakes (Intensity VIII-IX), which had a great impact on the development of architectural and construction styles.