New Insights Into Active Tectonics and Landscape Evolution of the Northernmost Chilean Central Depression

Abstract

Active deformation and landscape evolution in North Chilean forearc involve multiscale tectonic processes, such as crustal thickening causing orogenic‐scale uplift and faulting modulating the mountain‐front landscape. In the Central Depression, faults redirecting Quaternary drainages are poorly understood due to their subtle surface expressions and limited structural data acquisition. To address this, we combined remote‐sensing analysis of high‐resolution DEMs, satellite and UAV imagery, new geomorphic mapping, structural data, and morphometric analysis with available surface age dating to identify and give temporal constraints on previously unmapped faults impacting drainages across this region. Our findings reveal the reactivation of east‐vergent NNW‐SSE reverse to transpressive and NW‐SE strike‐slip faults over approximately 100 km of latitude. Faults movement can be summarized into two main stages (a) A Late Miocene‐Pliocene stage, dominated by east‐vergent reverse faults inverting the Andean piedmont in the northern study area. (b) A Pliocene‐Quaternary stage, characterized by transpressive activity of these east‐vergent faults extending southward, alongside structures of the West Vergent Thrust System. The tectonic evolution of the east‐vergent structures relates to the ongoing deformation of the coastal forearc, encroaching into the Central Depression. Minimum vertical and strike‐slip displacement rates since the Quaternary are 12 m/Ma and 90 m/Ma, respectively, with the potential for higher rates depending on the onset of displacement. Drainage pattern modification, driven by incremental vertical displacement rates, provides insights to qualitatively evaluate individual fault activity rates. Numerous recently detected structures represent previously unknown sources of seismic hazard, requiring further dating of geomorphic markers and high‐resolution monitoring.