COULOMB STRESS TRANSFER IN THE EASTERN CORDILLERA, COLOMBIA: COMPARISON OF PLANAR AND NON-PLANAR RECEIVER FAULT GEOMETRIES
Colombia is located in the northwest of the South American Plate, where the Nazca Plate subducts beneath it along the Pacific Coast. To the north, a complex tectonic setting occurs with the interaction of the Panamá-Chocó block, the Caribbean, and South American plates. The Andean region features multiple active crustal fault systems that separate crustal blocks of different ages, affinities, and stress regimes, known as the Northern Andean Block (NAB). According to GNSS data, the NAB moves northeast with an azimuth of 60º at a rate of 8.6 mm/yr, and the deformation is accommodated by faults within the NAB. To the east of the NAB, the Eastern Cordillera is composed of multiple active fault systems that separate the NAB from the cratonic region of the South American Plate. In the central part of the Eastern Cordillera, the Algeciras, Servitá, and Guaicaramo fault systems have generated significant earthquakes, including the 1917 M 7.0 Villavicencio event, which caused large landslides burying villages near the epicentral area and substantial damage in Bogotá, with many buildings severely damaged or destroyed. This study models Coulomb stress transfer for 16 seismic events with M ≥ 5 that occurred between 1917 and 2023. These events are related to sections of the Algeciras, Servitá, and Guaicaramo faults. The Coulomb stress transfer modeling is resolved on both planar and non-planar receiver faults to determine if non-planar receiver faults provide a better correlation with observed aftershock patterns. It also assesses the influence of Coulomb stress transfer on rupture behavior and the spatial and temporal distribution of moderate to large seismic events and their aftershock sequences. This research aims to contribute to the seismic hazard assessment in a region with approximately 10 million inhabitants exposed within 100 km from the studied seismic sources.