Chaotic Tremor

Chaotic Tremor

Vertical component seismograms and spectrograms from January 2, 2003 recorded at broadband station E1S (0.7 km from the lava lake) and short-period station MAC (2.07 km from the lava lake). Time units are shown in seconds. This tremor episode exhibits a broad spectrum. The spatial distribution of amplitudes suggests a shallow source close to the crater. Twenty minutes after the tremor onset, a brief (approximately 2 minutes) transition to harmonic trigger-type tremor with three harmonics and a fundamental frequency of 3.0 Hz can be seen. This audio record is sped up by a factor of 100 relative to the actual seismic signal.