Fig. 8

Map of frequency-dependent magma-related dv/v changes in three time periods marked in Fig. 5. a–c Period 1. d–f Period 2. g–i Period 3. In Period 1, the dv/v values are color-coded by averaging dv/v values between January 1, 2018 and March 15, 2018 (yellowish shaded zone in Fig. 5). In Period 2, the dv/v values are color-coded by subtracting dv/v value on March 15, 2018 from that on April 17, 2018 (bluish shaded zone in Fig. 5). In Period 3, the dv/v values are color-coded by subtracting dv/v value on April 17, 2018 from that on May 1, 2018 (reddish shaded zone in Fig. 5). The black dashed line indicates the fissures opened during the 2018 eruption