Radon is considered to be one of the most promising
gases to predicting the earthquake. The water radon concentration is regular to
monitoring indicator. The research on the formation of the earthquake radon anomalies
(ERA) will produce great academic value and economic benefits. The ERA in slope-type
can be seemed as a response of underground water radon anomalies in the progress
of tensile stress accumulating.
Earthquake predictions inChinahave had rare successes but suffered more tragic setbacks since the Xintai
earthquake in 1966. They have developed with twists and turns under the
influence of the viewpoint that earthquakes are unpredictable etc. Though the Wenchuan
earthquake of M8.0 in2008 inChina and the 2011 Tohoku earthquake of M9.0 inJapan were failed to predict, the GPS
observations before and after these 2 events have shown that there were precursors to these events and large
earthquakes are predictable. Features of different observation techniques, data
processing methods are compared and some recent studies on precursory crustal
deformations are summarized, so various advantages of GPS technique in monitoring
crustal deformation are emphasized. The facts show that anomalies or precursors
detected from GPS observations before the great Wenchuan earthquake have been
the most remarkable results of explorations on crustal movements and earthquake precursors in China. GPS is in deed an excellent
observation technique for earthquake prediction.
Since October 1, 2010, a GPS receiver is put into operation at Tokai (Japan) in an experiment on Neutrino Physics (T2K). A significant variation of the altitude was detected from the beginning of March 2011, so that it has made worthwhile to investigate the possibility that such variations could be correlated to the Tohoku earthquake. In order to investigate in details this possibility, we analyzed the GPS data collected during 2011 by GEONet the GPS Earth Observation Network (GEONET). GEONET is the GPS network of Japan and consists of 1240 permanent stations. Preliminary results of the analysis seemed to show ten days before the earthquake, some possible anomalous behaviors of the stations. These anomalous behaviors were particularly relevant for stations of the network near the epicentral area. While co-seismic and post-seismic variations are widely expected, the anomalies recorded about ten days before the earthquake could be seriously considered among short-term precursors of the earthquake. In order to confirm this possibility, more detailed studies have been performed. In particular, GEONET currently makes available only daily solutions of the stations coordinates. On the contrary, it is very important to improve the time resolution just to understand the features of the anomalies till the last hours before the Earthquake. For this reason, we have performed an analysis to evaluate the coordinates and movement on hourly basis so improving the time resolution.