When Faults Wriggle. Geomythological Evidence of a Pre-Hispanic Earthquake in Cusco, Peru

Many human communities across the globe have associated seismic activity and ground motion with mythological creatures believed to roam beneath the Earth’s surface. A recurrent expression of this association is the link between snakes and earthquakes in human folklore. In the Americas, the Chumash people of southern California attributed the frequent ground shaking along the San Andreas Fault to the movements of underground serpents. In Patagonia, the struggle between the snakes Trentren and Caicai occupies a central place in Mapuche mythology, embodying tectonic uplifts and subsidence associated with subduction earthquakes. In the central Andes, the amaru, a chthonian, serpent-like deity of pre-Hispanic cosmology, was likewise associated with violent geological or climatic processes, and its appearance was commonly perceived as a rupture in the equilibrium of the world, a pachacuti. In ancient and modern Peru, earthquakes have repeatedly reshaped landscapes and profoundly affected human societies. In the absence of an intelligible pre-Hispanic writing system, indigenous oral traditions, later recorded in colonial chronicles, represent a particularly valuable, yet long underexploited, source for identifying past extreme natural events. These transgenerational memories are nonetheless rooted in empirical environmental knowledge, conveyed through alternative narrative systems.

This contribution proposes a geomythological reinterpretation of a passage from the Relación de antigüedades deste reyno del Piru, written in the mid-seventeenth century by the indigenous author Pachacuti Yamqui Salcamaygua. The chronicle recounts the seemingly fantastic appearance of an amaru above the city of Cusco during the Inca period. Through a cross-analysis of toponymic, geomorphological, and seismological data, we suggest that the underlying event corresponds to a major earthquake during the 15^th century CE. The propagation of a surface rupture across the landscape may have been perceived as the sudden emergence of a serpent-like being wriggling over the mountains and leaving an undulating surface trace. If confirmed, this account may represent the oldest seismic event documented by written sources in South America. More broadly, this oral tradition may testify to the strong imprint of earthquakes on the collective memory of Andean societies by transforming a tectonic feature into a mythogenic landscape. Beyond its scientific implications, this geomyth also holds significant potential in terms of geoheritage and geoeducation. Within the framework of a French–Peruvian initiative, this cultural narrative has been adapted into an illustrated book to raise awareness of seismic risk among younger generations.