Spatial and Temporal Metrics for the Identification of Mining-Induced Seismicity: The Case of the Chilean Andean Margin

Identifying and distinguishing induced seismicity from background regional tectonic activity remains a major challenge within tectonically active settings, due to the overlap between natural seismicity and seismicity potentially triggered by human activities. Induced seismicity refers to earthquakes generated or modulated by anthropogenic processes such as reservoir impoundment, fluid injection or extraction, and mining. While mining-induced seismicity has been shown to increase seismicity rates and magnitudes in tectonically stable regions, fundamental uncertainties remain regarding the spatial extent of mining influence and its detectability in areas with high background tectonic activity. The case of study is in the Central Andes (18-36°S), in the Chilean Andean Margin. Here, long-lived subduction has shaped well-defined metallogenic belts hosting major metallic ore deposits, within which Chile has developed a long history of open-pit and underground mining across diverse geological and operational settings. We use regional crustal seismicity from a recently published regional seismic catalog, together with a database of large-scale open-pit and underground mining operations in Chile, to systematically evaluate spatial and statistical relationships between seismicity patterns and mining activity. Specifically, we apply a three-phase framework to identify seismic events with a higher likelihood of mining-induced origin. We first define a 15 km depth threshold to separate shallow seismicity potentially influenced by mining from deeper regional tectonic events, and distinguish near-field from far-field seismicity based on proximity to mining operations. We then apply a nearest-neighbor clustering method to identify stochastically independent events, which are more likely to be induced. Finally, distance to mines and clustering information are combined into a linear weighted metric that quantifies the likelihood of induced seismicity. The results reveal a marked daily temporal anomaly in shallow seismic behavior (depth < 15 km), where an increase in activity is observed in the near field of mines between 16:00 and 22:00, aligning with the mines’ primary operational windows and blasting schedules. Within this time window, the probability of events belonging to a tectonic cluster decreases, thereby increasing the likelihood that they are induced seismicity rather than aftershock sequences. The primary finding highlights a daily six-hour window that concentrates 70% of the total seismic activity in the near field of mines. This represents a concentration 2.8 times higher than normal compared to regional seismicity, which lacks a preferred time frame. These observations indicate that mining activities can impose a measurable temporal signature on seismicity, even within a tectonically active subduction margin, contributing to the broader understanding of how anthropogenic processes interact with natural seismic systems.