Fig. 2From: Magma reservoir beneath Azumayama Volcano, NE Japan, as inferred from a three-dimensional electrical resistivity model explored by means of magnetotelluric methodTan−1(\({\varPhi }\)2) of each site at various frequencies or periods (colored circles). The white contour lines represent with 2.5° width. The black and red triangles are the same as in Fig. 1Back to article page