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Fig. 4 | Earth, Planets and Space

Fig. 4

From: Ground water-induced changes in velocities of P and S waves (Vp and Vs) measured using an accurately controlled seismic source

Fig. 4

Temporal variations in travel time, ground water levels, and rainfalls. ac Show travel time variations of P and S waves. The solid and dotted lines show P and S waves, respectively. The uncertainties in the estimation are shown by the width between two horizontal bars. The bars labeled by \(\delta {t}_{\mathrm{N}}^{\mathrm{P}}\) and \(\delta {t}_{\mathrm{N}}^{\mathrm{S}}\) indicate the measurement error of P and S by Eq. (5), respectively. The bars labeled by \(\delta {t}^{\mathrm{P}}\) and \(\delta {t}^{\mathrm{S}}\) indicate the estimation error of P and S by Eq. (6), respectively. The uncertainties plotted in the figures are the average of one day (NU.MIK) and 60 days (N.THNH and N.MKBH) over the entire observation period. d Shows daily variations in the groundwater level at TYH1 (solid line), TYH2 (dotted line), and TYE (dash-dotted line). e, f Show daily rainfall observed at the Toyohashi and Mikkabi stations, respectively. The orange lines show the high precipitation period (wet season) from April to September 2018; the blue lines show the low precipitation period (dry season). The regions painted by orange and blue bars in a, d, and e show the periods used in the analysis for short-term travel-time change

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