Significant P wave attenuation for a specific frequency range beneath Kirishima Volcano, Japan

The three‐dimensional P wave attenuation structure beneath Kirishima Volcano, southwest Japan, was obtained through tomographic inversion of 469 P wave seismograms from 41 regional events recorded at 14 stations. Using band‐pass filtered P wave amplitude data, the inversion determined the deviatoric attenuation constants of 4 km × 4 km × 5 km (SW‐NE, SE‐NW, depth) blocks in the study volume as a function of seismic wave frequency. The result delineates strikingly high attenuation at the depth of about 5 km beneath the highest cinder cone, Karakuni‐dake, in the central region of Kirishima Volcano. The attenuation constant in this region shows strong frequency dependence with greatest absorption around 8 Hz. This result is interpreted to represent the absorption of seismic waves by an 80 m thick sill‐like magma body there.