Baseline characterization of seismicity for risk‑informed planning of geological CO2 storage: insights from Campo Colorado area, Valle Medio del Magdalena Basin, Colombia

Abstract

Geological CO2 storage in sedimentary basins associated with depleted hydrocarbon reservoirs represents a relevant strategy for climate change mitigation. In Colombia, the Valle Medio del Magdalena Basin, with a long history of hydrocarbon exploration and production, has been identified as a potential target region, particularly the Campo Colorado field. An additional factor supporting the selection of Campo Colorado is its proximity to the Barrancabermeja refinery, a major CO2 emission source. However, baseline seismic studies are required to assess its feasibility from a seismic risk management perspective. Given that the Valle Medio del Magdalena is tectonically active, a regional seismic characterization was conducted using the Colombian National Seismological Network catalog. The analysis focused on Campo Colorado within a 100 × 100 km polygon and included the Bucaramanga Seismic Nest as a comparative reference. Results indicate that progressive improvements in the seismic network enhanced catalog completeness, while the estimated b‑value for cortical seismicity in Campo Colorado, slightly higher than that estimated for the Bucaramanga Seismic Nest. Higher probabilities of occurrence for cortical events with magnitudes below 5.0 are observed in the study area. The estimated fractal dimension (Dc = 1.45) indicates a moderately clustered spatial distribution of seismicity, consistent with the regional structural framework and providing complementary information for the characterization of seismicity patterns. No significant temporal anomalies were identified, indicating that current seismicity is predominantly related to natural tectonic processes. Strengthening the local seismic network is recommended to improve baseline characterization, support real‑time monitoring, and facilitate future geological CO2 storage initiatives in the region.