Relatively short-term correlation among deformation, degassing, and seismicity: a case study from Concepcion volcano, Nicaragua
Artikel i vetenskaplig tidskrift, 2014
Concepcion is a frequently active composite volcano in Nicaragua, and is located on Ometepe Island, within Lake Nicaragua. Significant eruptive activity took place at this volcano between March and May 2010, consisting of ash and gas explosions (VEI 1-2). We compare geodetic baseline changes observed with global positioning system (GPS), sulfur dioxide flux (SO2), and seismic amplitude (SAM) data collected at Concepcion during April - June, 2010, and February - April, 2011. Time series analysis reveals a remarkable correlation among the data sets during 2010, when the volcano was erupting. In contrast, the volcano was at its background level of activity in 2011 and the statistical correlation among the time series is not significant for this period. We explain the emergence of correlation among the time series during eruptive activity through modeling of the GPS data with emplacement of a magma column in an open conduit. In the model, magma rose in the conduit, between May 5 and 14, 2010, from a shallow reservoir located at similar to 1.8 km depth. Later, between May 24 and 31, 2010, the top of the magma column descended to almost 600m depth, corresponding to the cessation of eruptive activity. Thus, cross-correlation and an integrated analysis of these geophysical time series on a timescale of days helps to reveal the dynamics of the magma plumbing system operating below Concepcion volcano.
Seismic amplitude measurement