During Nov.-Dec. 2001 Cotopaxi volcano showed important signal of activity. This volcano is one of the most actitve volcanoes of Ecuadorean Andes. It has exhibited a recurrence interval of around 100 yrs for important eruptions. The Instituto Geoficico monitored this volcano using a network of 4 short period seismic stations. This experiment aims to improve the detection capabilities using a temporary deployment of broad band three component seismic station. This station will allow to record long period and very long period events that we suppose are occurring at Cotopaxi