Myth or Truth: Was There a Tsunami in Lake Texcoco?

The Florentine Codex describes a natural disaster as a harbinger of the fall of Tenochtitlan; was there a tsunami in pre-Hispanic times?

Myth or Truth: Was There a Tsunami in Lake Texcoco?
Natural Protected Area of Lake Texcoco. Image: Capital 21

A tsunami was recorded south of Lake Texcoco in pre-Hispanic times, archaeologists confirmed. A natural disaster described in the 16th century Florentine Codex as one of the harbingers of the fall of Tenochtitlan, led a team of experts to investigate whether it could be a lake tsunami.

The hypothesis of archaeologist Gerardo Gutiérrez Mendoza, from the University of Colorado at Boulder, is based on the textual mention in the codex "that the water boiled and very far away as it rose upwards", something that according to the researcher can only "be described by someone who has witnessed a tsunami wave".

INAH reported that a team of experts from the universities of Colorado, Malaga, and UNAM went to Peñón Viejo or Peñón del Marqués, in Iztapalapa, where, according to their hypothesis, the tsunami was generated. This is an extinct volcano dating from the Quaternary period, which began 2.59 million years ago, but has been affected by human settlements and two active slope faults.

The project made it possible to prove, due to the presence of clays in the subsoil of Peñón Viejo, that there was indeed a landslide of materials that were deposited in the ancient lake. The experts estimate that the landslide mobilized 2 million cubic meters of material, of which 700 thousand ended up underwater.

"Our first result is that the volume of material that fell into the lake could have generated a tsunami wave," said Gutiérrez Mendoza, who used virtual models to show that 17 minutes and 55 seconds would have been enough for the tsunami wave to reach Tenochtitlan.

The archaeologist assured that these analyses prove the existence of, at least, a lake tsunami, but it has not been defined when such phenomenon occurred, the reason why it is still not determined if it was during the Mexica occupation of the island and if it perhaps influenced the narration of the Florentine Codex.

The team obtained, using a drone, terrain models, in addition to carrying out volumetric and photogrammetric studies of landslides, resistivity tests in Calzada Ignacio Zaragoza in Colonia El Paraíso and Ahome Street in Colonia San Lorenzo Xicoténcatl.

The advances of his research were presented in the cycle of conferences "Archaeology today" of El Colegio Nacional, coordinated by Leonardo López Luján, researcher of INAH.