Source Mechanisms of Harmonic Tremors at Sakurajima Volcano

Source mechanisms of harmonic tremors observed after B-type earthquake swarm (HTB) and those immediately after explosive eruption (HTE) at Sakurajima are estimated by inversion of root mean square (RMS) seismic amplitudes of components at / stations. HTB and HTE had a similar source mechanism that indicates isotropic components of more than /* . Source depths of the HTB and HTE correspond to the location of a gas pocket formed at uppermost part of the conduit. We infer that HTB is generated by resonance of the gas pocket formed after swarm of B-type earthquake and that HTE is related with resonance of the gas pocket of which top is partially collapsed by the explosion.

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