Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

378 PATA Days 2024 Several EAEs have been measured on the Temple of the Feathered Serpent and the Sun and the Moon pyramids (Fig. 2) for this study. The most abundant are dipping broken corners affecting the basalts blocks in the west staircases of the Temple of the Feathered Serpent, and the Pyramid of the Sun (Fig. 2b, 2c). The horizontal oscillation and loading between annexed blocks repeatedly hits and breaks the corner, dipping the internal friction angle of the lithology (Rodriguez-Pascua et al., 2011; 2023). In the case of the floating cantilevers of the west side of the Feathered Serpent Temple, a new type of EAE is described, the “floating dipping broken corner, FDBC”. This EAE affects the decorative overhanging blocks of the walls of the Feathered Serpent. This EAE is also generated by the horizontal shaking related to seismic loading, generating a free-oscillation between blocks, hitting the external lateral side, and breaking the external corner. The joint between blocks is dry (i.e. without mortar), which facilitates the lateral shaking between annexed blocks. This block deformation and rupture is difficult to associate with deliberate destruction since it does not change the sculpted religious representation. In addition, DBC and FDBC show one dominant oriented broken corner plane, which suggests the oscillation of the blocks, starts from SW to NE (Fig. 3). Archaeoseismic timeline of teotihuacan In antiquity, Teotihuacan experienced the impact of at least two powerful destructive earthquakes, with intensities reaching IX-VIII on the macroseismic scale. The first occurred during the Miccaotli phase, spanning from 1 to 150 CE, while the second struck around 455 ± 50 CE, during the Late Xolalpan-Early Metepec phase (Fig. 4). Additionally, three other significant earthquakes, with intensities equal to or less than VIII, affected the region during the Tlamimilolpa phase (225 ± 50 CE), the Early Xolalpan phase (400 – 425 CE), and the Late Metepec phase (600 ± 50 CE, Fig. 4). The combined effects of these ancient seismic events likely influenced the development of architectural styles in the area. However, it is the occurrence of the last two earthquakes before the city's abandonment circa 650 CE that are considered the most probable catalysts for its decline. Evidence of Earthquake Archaeological Effects (EAEs) is prevalent, with brittle dipping broken corners notably affecting structures like the west staircases of the Pyramid of the Sun and the Feathered Serpent. A novel observation of Floating Breaking Dipping Corners further strengthens the hypothesis of seismic