  On June 4 2011 the Puyehue-Cord\'{o}n Caulle volcanic system produced a
pyroclastic subplinian eruption reaching level 3 in the volcanic explosivity
index. The first stage of the eruption released sand and ashes that affected
small towns and cities in the surrounding areas, including San Carlos de
Bariloche, in Argentina, one of the largest cities in the North Patagonian
andean region. By treating the eruption as a Fermi problem, we estimated the
volume and mass of sand ejected as well as the energy and power released during
the eruptive phase. We then put the results in context by comparing the
obtained values with everyday quantities, like the load of a cargo truck or the
electric power produced in Argentina. These calculations have been done as a
pedagogic exercise, and after evaluation of the hypothesis was done in the
classroom, the calculations have been performed by the students. These are
students of the first physics course at the Physics and Chemistry Teacher
Programs of the Universidad Nacional de R\'{\i}o Negro.
