NOAA/WDS Paleoclimatology - Ammann and Naveau 2003 Statistical Analysis of Tropical Volcanic Events

Explosive volcanic eruptions are very violent events, each with clearly individual characteristics. Instead of looking at specific eruptions, we focus here on the long term record of tropical explosive volcanism. To assess the distribution of volcanic occurrences over several centuries we employ sulfate measurements from polar ice cores. From these measurements, we compile a binary time series of sulfate deposition events that left a signature at both poles. Because of the binary nature of this problem, a series of logistic statistical models are compared to best represent the data. These models demonstrate the existence of a strong multi-decadal variation in the occurrence of sulfur rich tropical eruptions. More precisely, a combination of a trend and a cycle explains best the evolution of eruption history. To corroborate this result with a record independent of the ice cores, we confirm these long-term variations with the most recent Volcanic Explosivity Index (VEI).