Fig. 4From: Shallow volcanic reservoirs and pathways beneath Aso caldera revealed using ambient seismic noise tomographyExamples of problematic monthly CCFs with low SNR (CMG–UMA), periodic signals (FKB–KSB), or temporary time shifts (JNU–TKD) for two BB and one SP station pairs. Monthly CCFs a before and b after eliminating significantly problematic CCFs (inside red dashed boxes). Other illustrations are the same as those presented in Fig. 3Back to article page