Repeated electronic distance measurements across Kilauea Caldera with Tellurometers and Geodimeter show definite horizontal expansion related to the vertical uplift and outward tilting of the summit prior to an eruption, and contraction during and after a flank eruption. Measurements started in October 1964, along a 3098 meter line between Uwekahuna and Keanakakoi, indicate a relatively uniform lengthening of 12 centimeters during the interval October 22, 1964 to March 1, 1965. Rapid shortening of the line by 28 centimeters was measured 4 days after the beginning of a flank eruption which involved emission of approximately 29 million cubic meters of lava during the period March 5 to March 15, 1965.