The city of Cusco, in the central Andes of Peru, was severely damaged by several earthquakes in pre-Hispanic times and since then. To the north of the city there is a system of active faults that offset glacial deposits. In this study, we focus on the Tambomachay fault, a 20 km long normal fault. The fault offsets moraines by up to 4 m, the age of which could be determined to be 14,2 ± 0.5 kyr using exposure dating (10Be cosmogenic nuclides). This means that the an average slip rate is 0.3 - 0.37 mm/yr in the Holocene. A paleoseismological trench across the fault yielded evidence of three earthquakes in the last 8-9 kyr that offset the surface. All three earthquakes occurred before the Inca period. This means that the historical earthquakes that caused devastation in Cusco may have been caused by quakes on other nearby faults.
The study was published in the diamond open access journal Tektonika:
Rosell, L., Benavente, C., Zerathe, S., Wimpenny, S., Aguirre, E., Walker, R., Grützner, C., García, B., Audin, L., Combey, A., Palomino, A., Delgado, F., Rodríguez-Pascua, M., Cardenas, J., & Carcaillet, J. (2023). Holocene Earthquakes on the Tambomachay Fault near Cusco, Central Andes. Tektonika 1.2. https://tektonika.online/index.php/home/article/view/27External link