B. Decker R. Decker 1991 <p>The last two decades have brought major advances in research on how volcanoes work and how to monitor their changing habits. Geologic mapping as well as studies of earthquake patterns and surface deformation associated with underground movement of magma have given scientists a better view of the inner structure and dynamics of active volcanoes. With the next decade, the time has come to focuses more on applying this knowledge toward reducing the risk from volcanic activity on a worldwide basis.&nbsp;</p> application/pdf en U.S Geological Survey Reducing volcanic risk article