Migration of tremor locations before the 2008 eruption of Meakandake Volcano, Hokkaido, Japan

We estimate the locations of three tremor sequences, denoted A, B, and C, that occurred before the 2008 eruption at Meakandake volcano, eastern Hokkaido, Japan, using the spatial distribution of seismic amplitudes of volcanic tremor. Although we used only five seismic stations, we could estimate the locations of three tremor sequences. We find two different tremor source areas: those of Tremor A located about 2 km southwest of the erupted crater (Area A) and the other about 1 km southeast to south of the crater as that of the Tremor C (Area B). The location of an early phase of the Tremor B is estimated in Area A while the location of its later phase appears to connect the two areas. This location migration during Tremor B occurred simultaneously with other important geophysical phenomena before the eruption event, as suggested by geodetic and geomagnetic studies. Our findings of the two tremor locations of the tremor sequences and location migration during Tremor B may be important for future monitoring activities at Meakandake volcano, particularly to forecast the location of a possible phreatic eruption.