Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week's contribution is from David Mencin and Glen Mattioli, geodesists with UNAVCO, Inc., in Boulder, Colorado. We all know what it is like to experience strain. The pressures of everyday life can leave you feeling contorted and stretched. Volcanoes are no different — they experience strain as well, and measuring that strain can help scientists understand a volcano's activity. Unlike you, when a volcano experiences strain it contorts or stretches. The very subtle change in shape of subsurface rock is called deformation. It can be caused by a variety of forces, including changes in magma pressure or even in the amount of water in lakes at the surface. But how can you tell how much strain a volcano is experiencing? Fortunately, the Yellowstone Volcano Observatory consortium includes UNAVCO, Inc. as a member organization, and they are experts at measuring