TRACKING BUBBLE BURSTS WITH SEISMIC AND INFRASOUND CROSS CORRELATION DATA FROM VILLARRICA VOLCANO IN CHILE, USING MATLAB

Volcanic seismic and infrasound data from one of Chile’s most active volcanoes, Villarrica, record the persistent outgassing activity from the lava lake. Discrete signals from the burst of bubbles at the surface of the lava lake were recorded in both the infrasound and seismic during 2010. In order to investigate possible differences in the locations of the bubble burst sources, we tracked changes in the relative arrival times of the infrasound and seismic signals from event to event. Processing and analysis of the seismic and infrasound data was done using Gismo tools in the matrix laboratory software, MATLAB. The method consisted on using cross correlation of the seismic and infrasound signals to determine the lag difference (in seconds) between both signals. By comparing the relative changes in the arrival times of the infrasound and seismic signals, we may infer changes in the source position or media velocities. We used data from April and May 2010 to and find small changes, consistent with changes in wind direction, gas temperature at the vent, or changes in the source position.