Fig. 7
From: An approach to source characterization of tremor signals associated with eruptions and lahars
Explosion events and eruption tremor signals. a Vertical unprocessed velocity seismograms for three explosion events. We estimated event duration as the interval during which the envelope amplitude averaged over a 2.5-s interval was larger than the noise amplitude before the event onset. Our estimated durations for events 2011-12-04, 2012-03-02, and 2012-02-04 were 67.5, 75, and 75 s, respectively. b Band-pass-filtered (5–10 Hz) vertical velocity seismograms for three eruption tremor episodes. Note that a, b are at different time scales