Procedure of measuring the transverse loop displacement as a function of time, for the first IRIS time period. Top: the original time-distance plot. Second: the wavelet-filtered plot with the estimated loop position superimposed. The section above the red dashed line has been used for measuring the loop position. Third: the measured loop displacement based on Gaussian fitting of the loop cross-section at each time. The light dashed lines are error estimates based on the half-width of the Gaussian profile. Bottom: the loop displacement as a function of time, achieved by subtracting a linear fit from the position. Colour represents the strength of the fit based on ridge strength.