Seismic events in and around volcanos, like tremors, earth quakes, ice quakes and strokes of lightning, are usually observed by multiple stations. The question rises whether classifiers trained for one seismic station can be used for classifying observations by other stations, and, moreover, whether a combination of station signals improves the classification performances for a single station. We study this for seismic time signals represented by spectra and spectrograms obtained from 5 seismic stations on the Nevado del Ruiz in Colombia.