| Summary: | We produced new multi-temporal Digital Elevation Models (DEMs) of the April 2007 summit collapse at Piton de la Fournaise from previously unused aerial photographs. This dataset revealed the precise temporal evolution of collapsed volume and caldera morphological changes. Four days after the onset of an eruption at an unusually low elevation, the summit started to collapse (20:48 UTC April 5th). During the first 30 hours, collapsing was relatively fast (840 m3 s-1 average), and continued for at least the following 12 days, at a slower rate (46 m3 s-1 average). On April 19th, the collapse reached 96% of its final volume, while the remaining 4% were probably attained by May 1st (end of lava emission at the vent). The post-collapse hydrothermal activity in the caldera is closely associated with the main ring faults evidenced as active during the collapse, which are now preferential paths for fluids to reach the surface.
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