Broadband seismic observations at Satsuma-Iwojima volcano, Japan

This paper reports the results of preliminary analysis of broadband seismic observations conducted at Satsuma-Iwojima volcano, Japan. The recorded broadband data show a wide variety of seismic features. Small (M similar to 0), short-period volcanic earthquakes characterized by a long (similar to 5 s) emergent phase and by nearly identical waveforms are located at the very shallow part of the summit crater. Long-period seismic pulses synchronized with a regular amplitude modulation of volcanic tremor have an interval of approximately 46 to 50 min. Each of the long-period pulses has almost identical waveform. Polarization of the long-period events suggests a very shallow source which can be interpreted as a result of a volume expansion mechanism. The correlation between the long-period seismic pulses and volcanic tremor seems to be associated with magma convection and the degassing process inside the conduit of the volcano.