Research of the seismic velocity variation under the Redoubt volcano

Volcanoes are the most rapidly changing and difficult to study geological features. Identifying physical signatures of processes occurring during seismic and volcanic activity is one of the most important problem in seismology. Here we reveal temporal changes of seismic velocity in the upper crust for two years of eruption activity of the Redoubt volcano. Based on correlation of continuous records of seismic noise at pairs of stations, we obtained correlograms for selected time periods. Using the stretching method, we obtained relative velocity changes between stations. These variations appear to be consistent with the results of repeated tomography that was previously derived based on body waves from local earthquakes.