Lanalhue Fault is a northwest-striking fault that marks the contact between two distinct units of continental basement, the Eastern and Western Series in south-central Chile, separating the Nahuelbuta Range Cordillera de Nahuelbuta to the east and the Arauco Peninsula and Basin to the west. The fault takes its name from Lanalhue Lake, which is located in part of the fault trace – the lake's elongated shape shows the NW-SE trend. The Lanalhue Fault is a major lithological boundary in the Chilean Coast Range to which Cordillera de Nahuelbuta belongs. The Nahuelbuta Range is composed by Carboniferous granitic core bounded by high-temperature metasedimentary rocks referred as the Eastern Series. The Arauco Basin contains over 3 km of Late Cretaceous to Holocene continental and marine sediments