Top: evolution of the v_T component (blue) at the apex of loop F2 showing a damped oscillation following an event possibly associated with an impulsive temperature increase. A large-scale trend was removed from the v_T time-series by fitting and subtracting a second-degree polynomial. Middle: evolution of the v_T component at the apex of loop F3 showing a sustained oscillation. Bottom: sustained oscillation in the time–distance plot of forward-modelled SDO/AIA 171 Å emission.