Fig. 1From: Understanding and forecasting phreatic eruptions driven by magmatic degassingBanded tremor observed on 7 September 1985 at the Nereidas seismic station located ~ 4 km south of the summit of Nevado del Ruiz. This tremor was measured 4 days prior to a phreatic eruption on 11 September. Each tremor cycle is 15–20 min’ duration. Reprinted from the Journal of Volcanology and Geothermal Research, Volume 41, Martinelli, B., “Analysis of seismic patterns observed at Nevado del Ruiz volcano, Colombia during August–September 1985”, pages 297–314, Copyright 1990, with permission from ElsevierBack to article page