Mechanism Generating Volcanic Tremor (II)

Abstract

Mechanism generating the volcanic tremor of the 2nd kind (characterized by the period of 3.5～7 sec and vertically and radially polarized orbit, as firstly pointed out by SASSA (1935) from observation at Aso Volcano, is deduced from volcanic gas issue exciting magma chamber. This process is completely connected with the gas stream through volcanic vent, by which, as shown in the paper (I) (WADA, 1980), the tremor of the 1st kind is generated. Thus both tremors are deduced from the unified time-stationary phenomena as the gas motion. The dimensions of chamber are estimated to be vertically 10～12 km and horizontally 6～8 km, based on the simplest model of chamber shape and the period of tremor.