Freezing rainstorms coupled with moderate winds have often been observed to cause telephone lines and power transmission cables to begin bouncing up and down. This slow frequency high amplitude oscillation, or galloping as it is sometimes called, can build up to large amplitudes before the oscillation either damps out or persists at some constant amplitude. It has been reported by Edwards and Livingston  that the amplitude of galloping on transmission lines has been as large as forty feet. Galloping oscillations occur at relatively low frequencies; from .1 to 1 Hz.  near the natural frequency of the suspended cable.
College and Department
BYU ScholarsArchive Citation
Coleman, Leland J., "A Study of the Effects of Some Parameters of the Galloping of Electric Transmission Lines" (1970). Theses and Dissertations. 7114.
Electric lines — Vibration