Direct measurements (13): Acoustic records
Sound is produced by bubble
breaking
at the surface of lava column /
lava lake
Bubble bursting at
the surface
of lava lake
(Kilauea, Hawaii)
bubble must have a
residual overpressure
Bubble breaking = balloon bursting ?
balloon bursting
frequency = sound speed / radius
Frequency measured on volcanoes: 1 - 10 Hz
sound speed = 340 m/s
+ radius = 2 m
frequency = 150 Hz
more than 1 order of magnitude discrepancy
the mechanism is not bubble
bursting such
as for a balloon