Tidal phase of Water level lags behind that of water temperature in Qi’xian observation well, China

Abstract:

There are about 34 observation wells of water temperature which can record the effect of earth tide in national earthquake precursory network center. In most of the 34 wells, tidal phase of water temperature lag behind that of water level, but the opposite phenomenon exists in several observation wells. We take Qi’xian well which has long recording history and continuous data as an example to analyze this phenomenon. We check the instrument’s time system by using water temperature and water level changes in response to some big earthquakes，and also check the tidal phase of water temperature and water level in Qi’xian well through harmonic analysis (Baytap-G software), as a result，we find the observation is objective.

The fact that Tidal phase of Water level lags behind that of water temperature in Qi‘xian observation well shows that water temperature changes may be independent from water level changes. Water temperature changes in this well might be interpreted by the stress-heat consumption hypothesis. This may be beneficial to the study of water temperature changes as an earthquake precursor.

Figure 1. Water temperature and water level records of the Qi‘xian well from February 26 to 27 in 2010．The coseismic changes due to the 2010 Sumatra earthquake is marked by an arrow．