THE METHODOLOGY OF QUANTIFICATION OF VOLCANIC EXPLOSIONS FROM BROAD-BAND SEISMIC SIGNALS AND ITS APPLICATION TO THE 2004-2005 EXPLOSIONS AT VOLCÁN DE COLIMA, MEXICO

Abstract

A methodology is proposed for the quantification of volcanic explosions based on three parameters derived from broad-band seismic signals: The counter force of the eruption F, the power of the explosion P and the duration of the upward movement of the gas slug in the conduit to the free surface of magma, D. This methodology was applied to the 2004-2005 sequence of explosions at Volcán de Colima, Mexico. The broad-band records of more than 100 explosive events were obtained at a distance of 4 km from the crater. We determined the counter force of the eruption by modelling the low-frequency impulse of the seismic records of 66 volcanic explosions and estimated the power of 116 explosions from the spectra of the high-frequency impulse. The power of Colima explosions spans five orders of magnitude; the counter force spans four orders of magnitude. We show that the power of a volcanic explosion is proportional to the counter force of the eruption. These parameters may be used for the elaboration of a scale of volcanic explosions. © 2006 The Authors Journal compilation © 2006 RAS.