Geodetic measurement of the local elastic response to the changing mass of water in Lago Laja, Chile

A geodetic station (ANTC) built in bedrock in southern Chile is undergoing non-steady vertical motion within a range of nearly 50 mm. These fluctuations are dominated by the earth’s local elastic response to the changing weight of water in a reservoir located about 20 km away. There is also an annual periodic component of motion that is attributed to global and regional patterns of loading, as well as a steady tectonic signal. The local loading response constrains the average elastic structure of the area, and implies a stiffness that falls near the lower end of the range observed in rock samples.