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Along the western slope of the Central Andes in the southernmost part of the Pampean flat-slab subduction zone segment (∼33°S), crustal Quaternary west-vergent reverse faults are found, but little is known about them. To better understand and characterize these faults, grouped as the Cariño Botado thrust fault system (CBF), we undertook a multidisciplinary study focused on remote sensing and field geomorphic and geologic mapping, sedimentary relationships, and fault characterization. Optically Stimulated Luminescence (OSL) and U Pb dating samples were obtained from faulted deposits to constrain the timing of fault motion. We combined the mapping, fault relationship descriptions, and age control to understand this system better and quantify tectonic rates here for the first time. The main CBF is best expressed with Late-Cenozoic hanging wall fault rocks over thrusting Quaternary coarse-grained alluvial fan deposits, and the fault zone is found over a large area and with an altered fault zone (∼0.5–2 km wide). The principal reverse fault segment of the CBF is well exposed in creeks, with an average dip of 40°E and an associated vertical throw (up to the east) of the hanging wall from ∼3.2 m up to ∼30 m. Five OSL samples, taken from tilted and untilted alluvial fan deposits adjacent to the CBF's main fault, yielded ages between 2.5 ± 0.2 ka and 9.0 ± 0.7 ka, supporting Holocene activity and ∼4.9 m of fault slip in the last ∼8.7 ka. Ninety-nine detrital zircons from fluvial terrace deposits in the study area were dated using U Pb ICPMS, giving mainly Oligo-Miocene ages. The youngest ages of detrital zircons are Quaternary (n = 3; ∼0.9–4.4 Ma), which indicates that CBF activity could have started as early as ∼0.9 Ma producing an accumulated hanging wall uplift of ∼130 m. The alignment of the fault profiles, creek and river knickpoints, and alluvial and fluvial deposits allows the most recent activity of the main CBF to be traced between 5 km and up to 15 km along the fault trace. Based on fault length, slip characteristics, and earthquake scaling relationships, earthquakes up to Mw 7.5 could be associated with the fault. Because of the clear relationship between the river incision, distribution of fluvial terraces, variation in sinuosity and stream power, and the location of the faults, we suggest that the tectonic uplift controls the hanging wall fluvial incision from ∼0.9 Ma to the present. The Quaternary (at least 0.9 Ma to present) active CBF shares geometric, structural, and rupture timing similarities with the nearby better-characterized San Ramón Fault system. The latter is located ∼50 km to the south along the eastern border of Santiago, the capital city of Chile. Both fault systems share a comparable morpho-structural setting with a consistent average N-S trend. Significant seismic hazard is associated with both the CBF and the San Ramon System, which may be linked structurally and temporally regarding previous surface ruptures and major earthquakes, and therefore remain important research targets. • Tectonic geomorphology of a west-vergent thrust at a flat-slab of the Andes • Studies fault exposures, uplifted terraces, and tilted alluvial fan deposits • Fault activity dated by OSL and U Pb applied to geomorphic markers • Space-time similarities between the San Ramón and Cariño Botado faults • Cariño Botado faults suggests a possible seismic hazard of up to Mw 7.5. [ABSTRACT FROM AUTHOR]

Abstract: Giant landslides, which usually have volumes up to several tens of km3, tend to be related to mountainous reliefs such as fault scarps or thrust fronts. The western flank of the Precordillera in southern Peru and northern Chile is characterized by the presence of such mega-landslides. A good example is the Latagualla Landslide (19°15′S), composed of ~5.4 km3 of Miocene ignimbritic rock blocks located next to the Moquella Flexure, a structure resulting from the propagation of a west-vergent thrust blind fault that borders the Precordillera of the Central Depression. The landslide mass is very well preserved, allowing reconstitution of its movement and evolution in three main stages. The geomorphology of the landslide indicates that it preceded the incision of the present-day valleys during the late Miocene. Given the local geomorphological conditions 8–9 Ma ago (morphology, slopes and probably a high water table), large-magnitude earthquakes could have provided destabilization forces enough to cause the landslide. On the other hand, present seismic forces would not be sufficient to trigger such landslides; therefore the hazard related to them in the region is low. [Copyright &y& Elsevier]