Fig. 2
From: Detection of crustal deformation prior to the 2014 Mt. Ontake eruption by the stacking method
Schematic diagrams of the stacking method. a The top panel shows two GNSS baselines extending across a spherical pressure source, and the bottom panel shows how an improved SNR is obtained by stacking time-series data for the two baselines. b The top panel shows two baselines crossing a tensile crack source. One baseline (A) is extended by the opening of the crack, and the second baseline (B) is contracted. By stacking the time-series data for the two baselines after first reversing the polarity of the data for baseline B, the SNR is improved (bottom panel)