Comparison of postseismic groundwater temperature changes with earthquake‐induced volumetric strain release: Yudani Hot Spring, Japan

We observed temporal variations of the groundwater temperature during two observation periods (May 1983–July 1984, September 1991–August 1995) at Yudani hot spring in Tottori Prefecture, Japan. The groundwater temperature is affected by tides, atmospheric pressure changes and earthquakes. Assuming that volumetric strain change is the cause of these temperature changes, we calculated the respective strain sensitivities of the groundwater temperature. As a result, the sensitivities estimated from theoretical volumetric strain changes by earthquake fault models are more than 1,000 times larger than those from tides and atmospheric pressure. We infer that the actual volumetric strain changes near Yudani hot spring due to the earthquakes are larger than theoretical strain changes calculated by earthquake fault models.