Figure 3
From: Gas flux cyclic regime at an open vent magmatic column inferred from seismic and acoustic records
(a) Spectrogram of vertical ground velocity, (b) Seismogram of original vertical velocity, (c) High-pass filtered seismogram (>10 Hz), and (d) Band-pass filtered seismogram (0.02–0.2 Hz) of grey shaded interval in Fig. 2. The spectrogram was calculated using a Fast Fourier Transform of 512 data points (time window of 5.12 s with a sliding interval of 1 s) and smoothed by a Parzen window. The green, red, and blue horizontal bars at the top of the figure indicate the timing of QP, PP, and EP respectively. The red arrows indicate the timing of explosions at the C crater. Very-long-period (VLP) events associated with explosions occurred at different craters are indicated by blue (NE) and green (SW) arrows. Infrasound waveform in the same time window is shown in Fig. 4. The grey shaded period in Fig. 3b is magnified in Supplementary Fig. 1.
