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

190 PATA Days 2024 southeast corner, and sealed doors and windows along the south wall. Similar exaggerated buttresses, torn walls, and extruded blocks are observed in small chapels around the plaza, as well as in various buildings, together with extensional fractures and undulating floors. Some of these features could be produced by abandonment and/or bofedal conditions of the central part of the site. However, damages extend to the higher, southwestern section of Mawchu Llacta, located on a platform or on colluvial deposits of older landslides above the marsh. The observed damages, particularly in the church and southwestern buildings, are proposed to be the result of co-seismic shaking. Displaced, torn, or foldedwalls imply a minimum shaking intensity of VIII (according to EAEs by Rodríguez-Pascua et al., 2013). Notably, buttresses from different periods, remnants of reconstructions, and other features hint at multiple smaller seismic events and accumulated damage over time, rather than a single large earthquake. The Colca Region's history of frequent, relatively small, and shallow earthquakes over the past 30 years (e.g., Gaidzik & Więsek, 2021; Gaidzik et al., 2022; Woszczycka et al., 2024) suggests that seismic activity in previous centuries may not have significantly exacerbated by the M 5.5 event in 2022 and previous earthquakes, led to the collapse of the Lari church tower in the subsequent year, following an event with a magnitude less than 5 on June 2, 2023. Similar conditions are evident in many churches throughout the Colca Valley, as documented by the authors of this study and reported by the custodians of these churches (e.g., Lari, Tuti, Chivay, Achoma, Maca; Fig. 2). According to parish records, the town had deteriorated significantly by the early 19th century and was officially abandoned by 1843, and relocated 1.5 km downslope to the present village of Tuti (Wernke et al., 2015; Ramos Yucra, 2018), which church after 150 years of usage show similar deformations as the ruined church in Mawchu Llacta (Fig. 2). We claim that one of the main reason these “bad conditions” were frequent sesmic events resulting in accumulated structural damages in church and other buildings. C O N C L U S I O N S In this study, we applied archaeoseismological methods to examine four settlements in the Upper Colca Region focusing on their ruins and/or churches, in order to understand repeated abandonment- resettlement pattern. We conclude that the abandonment of Malata is thought to be politically motivated. Observed sparse deformations could be caused by 1) earthquakes occurring after this site desertion and/or 2) its abandonment and neglect. In Laiqa Laiqa, it is suggested that an earthquake, even if not highly destructive (intensity VII), accelerated the decisiontoabandonthe site, eitherduring its construction or right after the establishment, as according to written sources it lasted around 15 years maximum. No signs of buttresses or other forms of fixing the damages (collapse filling is much younger) suggest that the site was abandoned after the destruction. For Mawchu Llacta, the church's conditions, marked by titled walls, a collapsed tower, and exaggerated buttresses, suggest structural damage caused by a series of probably relatively small earthquakes. Each of these seismic events led to further destruction, necessitating the installation of an additional buttress. A comparable scenario involving minor to moderate damages caused by relatively small events occurring every few years is evident in today's churches in this region, such as Tuti, Lari, Maca, etc. Additionally, the site effects amplified the observed co-seismic deformations. The gradual accumulation of structural damage to both the church and the town, in addition to the swampy terrain, likely played a role in the decision to abandon this site church, opting for relocation instead of extensive repairs in a structurally vulnerable setting. Similarly, the repeated small tomoderate earthquakes and the consequent slope movements and resulting damages in present-day Maca, situated in the Colca Valley, could potentially necessitate the relocation of the town. Thus, the seismic hazard in this area encompasses more than just subduction earthquakes, highlighting the importance of studying crustal faults and shallow events. Although these may be localized, they have the potential to cause significant damage. A C K N O W L E D G M E N T S This research was funded by the National Science Centre (Poland), grant No 2020/39/B/ST10/00042. Special thanks to Paul Navarro for all the help in the field and to the local communities of the upper Colca drainage basin for kindly giving us access to work and help in the field.