Wideband acoustic records of explosive volcanic eruptions at Stromboli: New insights on the explosive process and the acoustic source

Publisher： John Wiley & Sons Inc

E-ISSN： 1944-8007|41|11|3851-3857

ISSN： 0094-8276

Source： GEOPHYSICAL RESEARCH LETTERS, Vol.41, Iss.11, 2014-06, pp. : 3851-3857

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

AbstractWideband acoustic waves, both inaudible infrasound (<20 Hz) and audible component (>20 Hz), generated by strombolian eruptions were recorded at 5 kHz and correlated with video images. The high sample rate revealed that in addition to the known initial infrasound, the acoustic signal includes an energetic high‐frequency (typically >100 Hz) coda. This audible signal starts before the positive infrasound onset goes negative. We suggest that the infrasonic onset is due to magma doming at the free surface, whereas the immediate high‐frequency signal reflects the following explosive discharge flow. During strong gas‐rich eruptions, positively skewed shockwave‐like components with sharp compression and gradual depression appeared. We suggest that successive bursting of overpressurized small bubbles and the resultant volcanic jets sustain the highly gas‐rich explosions and emit the audible sound. When the jet is supersonic, microexplosions of ambient air entrained in the hot jet emit the skewed waveforms.