Correlations Analysis on co-seismic response between well water level and temperature caused by the Nepal Ms8.1 earthquake

Abstract:

It was recorded that a large number of co-seismic response of well water level and temperature in Chinese mainland caused by the Nepal Ms8.1 earthquake. There was good correlation between well water level and water temperature for 51 observation wells, which appear as water level rise-water temperature rise, water level drop-water temperature drop or water level oscillation-water temperature rise/drop(most of the co-seismic water temperature drop). The good correlation is resulted from the groundwater dynamics. It refers to the role of groundwater wells thermodynamic temperature change is caused by the well-aquifer water movement. Under the pressure, the aquifer groundwater flow into the wellbore so that the well water movement from the bottom up, then the water level rises; Instead, the water level dropped. When the water temperature gradient is positive, the sensor temperature rises; In contrast, borehole sensor temperature drops, which explains the same step change of well water and well water temperature.

As for three observation wells, the change in water level is in the opposite direction to the change in water temperature, which is the post-seismic effect. Meanwhile, one observation well has only water temperature co-seismic change but no water level change, which may have great relation to the borehole condition, water temperature gradient, sensor position and water depth. The results also show that there is complex relationship between of time and amplitude of groundwater level change and those of groundwater temperature change, which is affected by borehole conditions and temperature gradients.