Fig. 4From: Monochromatic infrasound waves observed during the 2014–2015 eruption of Aso volcano, JapanPower spectra for Aso infrasound signals. Power spectra of a 10-min and 30-s records (black and gray lines, respectively) for the times of various surficial phenomena (a Strombolian explosion; b ash ejection; and c emission of gas-steam mixtures). Same data of Fig. 2 are used to calculate the spectra. Red line in a is data on March 25, 2015, when the intense Strombolian explosions and gas exhalations were observedBack to article page