Fig. 6

Time series of cc values and estimated dv/v in three frequency bands. a, b 0.9–2.0 Hz. c, d 0.6–0.9 Hz. e, f 0.3–0.6 Hz. Grayish shaded zones mark 10 days following the occurrence time of earthquake No. 1–3 and No. 6. Yellowish shaded zone represents Period 1 (P1, from December 20, 2017 to March 15, 2018). Bluish shaded zone represents Period 2 (P2, from March 15, 2018 to April 17, 2018). Reddish shaded zone represents Period 3 (P3, from April 17, 2018 to May 1, 2018). Dashed lines mark the occurrence times of earthquakes shown in Fig. 1. Green lines after P3 mark the May 2 eruption near Leilani Estates