Various field experiments were carried out using a 1000m deep borehole at Inagawa town, about 10km north of the focus of the Hanshin-Awaji Great Earthquake and directly above the area where shallow earthquake activities have intermittently occurred. These experiments included stress measurement by hydraulic fracturing, hydrophone-aided VSP, permeability tests and observation of various types of logging. The laboratory experiments were also carried out, including measurement of various properties and stresses of the core samples. The stress-depth relationship, determined by the hydraulic fracturing method, shows that the stress gradient well coincides with the Western Japan standard at a depth up to 700m, whereas it is approximately twice as high as the standard at a depth of 946m, at which core disking and borehole break-out are clearly observed, and hence stresses conceivably concentrate locally. Orientation of the maximum horizontal compressive stress is E-W at a depth of around 600m, but greatly changes to NNW-SSE at a deeper position. 4 refs., 5 figs.