Ice velocity, acceleration, and strain-rate are being measured at intervals of about 45 d using automated processing of aerial photographs. Preliminary results for the lowest 6 km of Columbia Glacier for the period July 1976 to November 1977 show the following: (1) High rates of flow (2–6 m/d) and longitudinal extension (occasionally exceeding 1/a). (2) A smooth, almost sinusoidal change in velocity 6 km above the terminus from about 2 m/d in August 1976 and 1977 to about 3 m/d in February–March 1977. (3) Very rapid increases in velocity near the terminus in October 1976 and September–October 1977 which follow embayment formation (increased iceberg calving). (4) A suggestion that the rapid velocity increases propagate up-glacier for 3–4 km before becoming unrecognizable. (5) Seasonal changes in velocity (which presumably relate to basal sliding) ranging from about 1 m/d 6 km above the terminus to about 4 m/d near the terminus.
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Mark F. Meier (1979) studied this question.