Process of emplacement of the andesitic blocky lava flows as derived from the seismic signals: Volcán de Colima

Abstract

Abstract Andesitic blocky lava flows are characterized by the surfaces that consist of large angular blocks of lava. They move slowly downhill the slope of volcano. These flows often travel only a few kilometres from the vent. In this paper, we first describe the possibility to apply the seismic signals, recorded during the blocky lava flows discharge, for reconstruction of the lava flow emplacement during the 2004 and 2016 eruptions at Volcán de Colima, México. There were shown the characteristic properties of lavafalls in comparison with the pyroclastic flows and igneous rockfalls (PFIRs), generated during Vulcanian explosions. It was shown that the waveforms of lavafalls are similar generally to the waveforms of PFIRs but are characterized by higher frequencies. The dominance of the short-duration seismic signals of lavafalls, comparative with the signals of PFIRs, indicates relatively smaller dimensions of lavafalls. We introduced the power spectral density curves of one-hour seismic signals as a tool to reconstruct the emplacement dynamics. It was shown that the lava outflowed from the crater in two ways, as lava pulses or as lava large-volume collapses.