摘要：Surface-elevation change and ice velocities have been measured over the debris-covered tongue of Chacraraju, Peru. Elevation change was measured by reflectorless survey at a 1 m horizontal resolution over three separate areas of the glacier between 2004 and 2005. Area-averaged change revealed general lowering, with two of the surveyed areas experiencing surface lowering of 0.58 and 0.77 m, and the third a rise of 0.07 m. Combining all three areas (43 216 m 2 ) resulted in a mean net lowering of 0.43 m a −1 , which is at the higher end of the range of long-term studies in the region. Velocity was measured over 7 days by the repeated optical survey of 12 prisms attached to stakes inserted directly into the glacier’s surface. Results indicate that velocity increases approximately with distance squared from the glacier’s terminus, from <10 mm d −1 near the terminus to approaching 100 mm d −1 at the base of the glacier’s icefall, located ∼1.7 km up-glacier. Velocity vectors also changed systematically along the glacier, from a consistent down-glacier orientation near the icefall to more variable orientations within ∼300 m of the terminus. No up-glacier motion component was measured.
