Variations in temperature, water level and chemical composition of the Toya hot springs due to the activity of the Usu double volcano in 1977 were investigated. Following results were obtained in 1978.
Temperatures of hot springs investigated increased gradually during a series of the phreatic explosions that followed on the initial explosions.
The water level of them rised more or less in the area keeped relatively high temperature.
By the variation of chemical composition in water, the hot springs in the Toya area can be divided into two groups; one is characterized by the increase in both chloride concentration and water temperature; the othes by the increase in bicarbonate content but the decrease in pH.

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Preseismic and coseismic changes in groundwater level at the earthquake on February 20 and June 12,1978, both of which occurred off the coast of Miyagi prefecture, are studied. The study was conducted by the data recorded at wells installed for the protection of groundwater resources in Miyagi prefecture. The record of groundwater level change is so complicated due to superimposing of various kinds of noises, that processed trend lines instead are mainly analyzed. The trend of groundwater level for 30 days,10 days and 0.5-1 days preceding each earthquake showed normal pattern, without any signs of preseismic effects. The coseismic change in groundwater level is detected at all wells. The direction of the change did not coincide with stress distribution which is estimated from initial shock of seismic wave. The amplitude of level changes decreased with an increase of depth of strainers. This phenomenon is regarded as a result of sediment compaction by seismic vibration.

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[in Japanese]

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