IRENA DUSHI, KOZETA TUSHE, MERITA XHIXHA
Abstract
This study examines variations in indoor radon concentration observed in Tirana (central Albania) during 2022 and explores their possible connection with seismic processes associated with nearby active tectonics, considering the 5 October 2022 Zall-Bastar earthquake (Ml 3.7) as a candidate seismic event for investigating a possible radon-related precursor signal. A pronounced increase in indoor radon concentration (ΔRn ≈ +1340 Bq/m3) was evidenced within the monitoring period preceding the event. This amplitude largely exceeds the locally established indoor radon background level and reaches values comparable to those commonly reported near active fault zones, despite the monitoring station being located approximately 12–20 km from the earthquake epicenter. The temporal evolution of the radon signal indicates that the anomaly developed during a period of low background seismicity, making aftershock-related or short-term environmental effects unlikely and indicating a deviation from the local baseline behavior. Comparable radon behavior has been documented worldwide in studies of radon variability preceding seismic events. Although the absence of long, continuous radon time series limits a definitive assessment of causality, the documented sequence of an extreme radon increase followed by a nearby seismic event represents a robust observational fact. These results suggest that continuous, well-calibrated indoor radon monitoring, interpreted within a local geological and seismotectonic framework, may contribute to the establishment of such monitoring as a standard observational approach for investigating potential seismic precursor processes in Albania and comparable tectonic settings.
Key words: pre-seismic anomaly, indoor radon, precursor, Zall-Bastar, ΔRn.