# Responses of Water Temperature and Level to Large Earthquakes in Tibet
## 3 Results
### Co-Seismic Response of Underground Fluid Observation Wells at Lhasa Station
#### 3.2.2 Case Analyses of Earthquakes with Different Magnitudes  
We selected five earthquakes with different magnitudes from the 15 earthquakes recorded in the study area for a case study analysis (Figure 6 and Table 2). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
\begin{tabular}{c} **Time of** \\ **Earthquake** \\ \end{tabular} & **Lat (\({}^{\circ}\))** & **Lon (\({}^{\circ}\))** & **Depth (km)** & **Magnitude (Ms)** & **Location** & **Epicentral Distance (km)** & **Water (km)** & **Water (km)** & **Water (km)** & **Water (km)** & **Water (km)** \\ \hline
2010-04-14 & 33.10 & 96.70 & 33 & 7.2 &
\begin{tabular}{c} Yushu, \\ Qinghai \\ \end{tabular} & 660 & 0.013 & 0.0021 & Yes & Yes \\
2016-04-13 & 23.14 & 94.87 & 130 & 7.2 &
\begin{tabular}{c} Miandian \\ \end{tabular} & 820 & 0.002 & 0.0027 & Yes & Yes \\
2017-11-18 & 29.75 & 95.02 & 10 & 6.9 &
\begin{tabular}{c} Milin, \\ Tibet \\ \end{tabular} & 385 & None & 0.0013 & No & Yes \\ \hline
2011-09-18 & 27.04:05.0 & 27.00 & 88.20 & 20 & 6.8 & India & 350 & 0.010 & 0.0009 & Yes & Yes \\ \hline
2008-10-06 & 29.80 & 90.30 & 8 & 6.6 &
\begin{tabular}{c} Dangio, \\ Tibet \\ \end{tabular} & 72.9 & None & 0.0072 & Fault & Yes \\ \hline
2009-09-21 & 27.30 & 91.50 & 10 & 6.3 &
\begin{tabular}{c} Budan \\ Tibet \\ \end{tabular} & 260 & None & 0.0023 & Fault & Yes \\ \hline
2019-04-24 & 28.40 & 94.61 & 10 & 6.3 &
\begin{tabular}{c} Metok, \\ Tibet \\ \end{tabular} & 374 & None & 0.0008 & No & Yes \\ \hline
2010-11-30 & 29.80 & 90.40 & 9 & 5.3 &
\begin{tabular}{c} Dangio, \\ Tibet \\ \end{tabular} & 64 & None & 0.0010 & No & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._(1) M9.0 earthquake in Japan [36; 37; 38]. On 11 March 2011, an M9.0 earthquake occurred in Japan, approximately 4790 km away from the Lhasa geomagnetic station. The water level and water temperature of the observation well exhibited obvious co-seismic responses to this earthquake. The water level oscillated (hydroximic wave), and the double amplitude of the water level reached 0.101 m before slowly dropping after the earthquake (Figure 6(a1)). Figure 6(a1) shows that the sudden convex jump that occurred approximately one hour before and after the earthquake had nothing to do with the earthquake. From 27 July to 23 November 2009, the record was broken, and this phenomenon continued since work was resumed on the 24 th. At the same time, the water temperature of the well experienced a rapid co-seismic (postearthquake) rise for 21 min and then dropped back to the pre-earthquake level after 2 h and 10 min. The maximum range of the well water temperature was 0.0056 \({}^{\circ}\)C (Figure 6(b1)). (2) M8.0 earthquake in Wenchuan [39; 40; 41; 42; 43; 44]. On 12 May 2008, an M8.0 earthquake occurred in Wenchuan County, Sichuan Province. The earthquake was approximately 1200 km away from the well at the Lhasa geomagnetic station. The water temperature and water level series recorded at the observation well exhibited obvious responses to this earthquake. The water level exhibited a water shock wave (shock), but no obvious change occurred subsequently. The maximum single amplitude was 0.075 m (Figure 6(a2)). At the same time, the water temperature series also recorded that the co-seismic temperature (postearthquake) first increased by 0.0066 \({}^{\circ}\)C and then decreased to 0.0079 \({}^{\circ}\)C (Figure 6(b2)). (3) M7.3 earthquake in Yutian, Xinjiang [45]. On 12 February 2014, an M7.3 earthquake occurred in Yutian, Xinjiang, approximately 1070 km from the Lhasa well. The response of the well water level to this earthquake was obvious. The water level exhibited a water shock wave and slowly rose following the earthquake, with a maximum amplitude of 0.17 m. In contrast to the other earthquake trains, small convex steps appeared approximately 7 h and 2 min before the earthquake. Whether an abnormality was recorded before the earthquake needs to be analyzed in-depth (Figure 6(a3)).