Anomalías de gas radón asociadas a la sismicidad en la región volcánica de los coconucos (cauca, colombia)

Abstract

A study of the correlation of seismicity with radon in soil emissions (222Rn) was carried out at Coconucos volcanic region by using three isotopic stations located close to geological faults for the period of 2006-2013. In this study, a radon anomaly was considered as those values above the average plus half of the standard deviation. These radon anomalies were correlated with earthquakes with a local magnitude (ML) greater than 2.8, concluding that radon anomalies above 2300 pCi/L were associated with a further occurrence of earthquakes with ML > 2.8 for a radius of 35 km taken from the center of the radon stations network. The difference in time between the detection of the radon anomaly and the occurrence of the earthquake ranged from 3 to 84 days, with 31 days average. From a total of 15 local earthquakes with ML > 2.8 that occurred during the studied period, 13 were associated with a previous radon anomaly, resulting in a probability of detection of 87 %. These results suggest that the regular measuring of radon in soil using a well-established network of isotopic stations is a good tool for forecasting the seismicity in the Coconucos region.