The determination of glacier speed by time-lapse photography under unfavorable conditions

Two practical problems in the use of time-lapse photography for the measurement of speed were encountered during the recent surge of West Fork Glacier in the central Alaska Range, Alaska, U.S.A. The first is severe rotational camera instability; we show how natural, unsurveyed features of the valley wall can be used to make the necessary corrections. The second problem is the computation of absolute speed when many different, unsurveyed glacier-surface features are used as targets