Fine-scale motion of the radio sources. (a) The running ratio image of the eruption in AIA 193, 211, and 171 Å channels at 02:49:11 UT. The positions of the type II sources of 133.36 MHz (red) and 133.22 (purple) MHz are plotted over the image for a duration of 5 min, represented by red and purple bars, respectively. The dynamic spectra in panels b and c on the right show the peak amplitude of the Gaussian-fitted source. The arrows represent the instantaneous change in direction (θ_i + 1 − θ_i) of the source motion for different frequencies (131.58, 131.74, 131.94, 132.08, 132.86, 133.02, 133.22 and 133.36 MHz) in the channel. The blue arrows represent when the change in angle lies between 0 and π radians. Similarly, the red arrows represent when the change in direction lies between 0 and −π radians. Panel c shows a zoomed-in view of the region marked in panel b. In panel c, one can see that, at each time point, the arrows point in almost the same direction across nearby frequency channels, exhibiting the correlated fine-scale motion.