ラドン観測 (1) -予備観測-

Abstract

For earthquake prediction, precursory phenomena before the large earthquakes have beeninvestigated in many countries.In China and some other places, they made a success of predictions of the large earthquakesby catching precursory phenomena. Variation of Radon content of underground gas and wateris also one of those phenomena.In our country, the decrease of Radon content was observed several days before the largeearthquake which occurred near Izu Peninsula on January, 14, 1978.We also begin to observe variation of Radon content of underground gas. Our porpuseof observation is study of the change of content of Radon gas before and after earthquakes.According to the results of the test investigation, the change of atomospheric pressure ismutually related with variation of Radon content in soil gas. Effect of atomospheric pressureis about one Eman, which is significant value comparison with the change, before the largeearthquake, a few or several Emans.But, when correction of atomospheric pressure's effect was done, the change of Radoncontent maybe decrease 5/100 Emans.Above result tells the possibility of detecting the precursor of large earthquake, if Radoncontent change was over a few Emans.