Groundwater level and groundwater temperature have continuously been monitored at 16 sites in the Aizu Basin, Fukushima Prefecture. Groundwater level, which declined by pumpage for snow-melting in winter around the urban areas, gets recovered in summer. However, it cannot necessarily reach to its level of previous years. In these sites, water balance may be deficit. Groundwater temperature in some deep wells declined year by year. This is because groundwater in shallow aquifer is drawn downward by decline of groundwater level in deep wells in winter. In this region, groundwater temperature is considered to be affected by not only thermal conductivity but also the induced groundwater flow by artificial pumpage.
Towada volcano is an active volcano located in the northern part of the Northeast Japan arc. K–Ar ages of lavas exposed at the Towada caldera wall were determined to establish a detailed eruptive history during the pre-caldera stage of Towada volcano. The obtained K–Ar ages were 0.26 ± 0.07 and 0.13 ± 0.06 Ma for Ohanabeyama Lava and 0.09 ± 0.06 and 0.09 ± 0.06 Ma for Hakka Lava and Pyroclastics. Although these K–Ar ages have large error ranges, they are consistent with stratigraphy. Distal tephra stratigraphy at the Kamikita Plain suggests that the main volcanic activity of Towada volcano have started at no earlier than ca.0.22 Ma. The newly obtained K–Ar ages of proximal lavas are consistent with the onset age of the volcanic activity estimated from the distal tephra stratigraphy.