Fig. 2
From: S-wave attenuation structure beneath the northern Izu–Bonin arc
a L-curve plot of \({{\left( {\nabla \log Q_{0}^{ - 1} \left( {\mathbf{x}} \right)} \right)^{ \, 2} } / N}\). Black and gray symbols reflect the smoothness of γ. b L-curve plot of \({{\left( {\nabla \gamma \left( {\mathbf{x}} \right)} \right)^{ 2} } /N}\). Black and gray symbols reflect the smoothness of Q −10 . The red arrow and dotted line indicate the corner of the L-curve that we chose in this study. c Plot of \(\left( \nabla \log Q_{0}^{ - 1} \left( {\mathbf{x}} \right) \right)^{2} / N\) against \(w_{{Q_{0} }}\). d Plot of \({{\left( {\nabla \gamma \left( {\mathbf{x}} \right)} \right)^{ \, 2} } / N}\) against \(w_{\gamma }\)