We report radon data collected during 1980 from geothermal wells in Iceland. Discrete radon samples are being collected weekly from nine stations in the Southern Iceland Seismic Zone (SISZ) and two stations in the Northern Iceland-Tjornes Fracture Zone (TFZ) to determine the potential for earthquake prediction. We also monitor volume ratio of gas to water, wellhead temperature and chloride content of the water to enable us to constrain the possible mechanism involved in radon anomalies.
We report a possible strain event in April that caused both changes in radon emission and a small earthquake swarm. An eruption at Hekla in August was not preceded by any distinctive radon anomalies. Swarm activity occurring close to Selfoss and Oxnalaekur appeared to be associated with possible low amplitude (<30%) precursory radon anomalies in April and October.
We present the first data from our ALOKA-continuous radon meter at Fludir. The data show no anomalies and no earthquakes have been reported.
Chloride and radon data from Bakki and Dalvik indicate that an inverse correlation exist between them at longer periods. Therefore, we feel that in the case of a large earthquake the chloride data could tell us something about the mechanism of radon anomalies.
During 1980 three major eruptions and two subsurface migration events occurred at Krafla, north Iceland. All of these events were followed by an increase in radon emission except for the event in July when no data were collected.
