Harmonic ionospheric oscillation by the 2010 eruption of the Merapi volcano, Indonesia, and the relevance of its amplitude to the mass eruption rate

Using continuous data from ground-based Global Satellite Navigation System (GNSS) receivers in Java and Sumatra, Indonesia, we studied the response of ionospheric total ionospheric electron content (TEC) to the 2010 Nov.5 eruption of the Merapi volcano in central Java. We then compared the results with the case of the 2014 Feb.13 eruption of the Kelud volcano, eastern Java. The TEC showed a quasi-periodic oscillation of a frequency ~4 mHz with average amplitudes of 0.9 and 1.8% relative to background values lasting for ~20 and ~ 120 min for the Merapi and Kelud eruptions, respectively. By comparing the two cases, together with the 2015 April eruption of the Calbuco volcano, Chile, we found the relative TEC oscillation amplitude may scale with the mass eruption rate. This suggests that the product of such TEC oscillation amplitude and the duration provides a new measure for the total volume of the volcanic deposits.