Global occurrence of large volcanic collapses in a changing climate.

From Google Earth imagery and published data on Quaternary volcanoes worldwide, this paper presents a semi-quantitative analysis of large volcanic events inventory in worldwide examples during Quaternary periods. Volume, area, the run-out distance on the surface avalanche units, the ratio of the vertical drop with run out distance are calculated to characterize the avalanche mobility. Morphological parameters of volcanic destabilization imply critical stability of volcanic edifices and cyclic evolution of volcanoes. Alignment of collapsed volcanic complex along fault zones are related to slab depth of oblique subduction zones. From the statistical dataset, a few equations have been developed, indicating a co-genetic evolution of avalanche deposits. Positive correlations are established between times, latitudes, the ratios of the vertical drop with run-out distancearound 0.05 -0.18, the run-out distance, and the volume or flow area of avalanche deposits.The morphological variations of the debris-avalanche deposits are associated with the avalanche dam-break-out and reworked deposits with matrix transformation and dilution during quarternary climatic variations. The oldest Pleistocene avalanche deposits show successive transformations into lahar deposits within a continental extensional context. Flow transformations are identified during the transitional context of the Maunder Minimum during the Little Ice Age. Climatic conditions durin the Greenlandien and the Spörer minimum contribute to reduce the large volcanic destabilization. These results highlight the importance of semi-quantitative studies along avalanche fault zones to better constrain subsequent hazardous flows related to the effects of climate change.