The timescales of magmatic processes prior to a caldera-forming eruption of Santorini

My Ph.D. was on the >10 km3, 22-ka Cape Riva eruption of Santorini, Greece. I looked at a series of lavas and minor pyroclastic deposits that erupted prior to the Cape Riva. This eruptive sequence had previously been described as “precursory leaks” from a slowly growing magma reservoir that went on to feed the Cape Riva eruption itself. However, I found that these “precursory leaks” are enriched in incompatible trace elements relative to the Cape Riva, showing that they must have evolved separately. 39Ar/40Ar dates and diffusion chronometry shows that the assembly of the Cape Riva reservoir was rapid, and much of the magma arrived in the shallow system a few decades before eruption.

Further reading:

How Long Does it Take to Build a Caldera-Sized Magma Reservoir? Earth Observatory of Singapore Blog, 03 May 2018

Fabbro, G.N., Druitt, T.H., Scaillet, S., 2013. Evolution of the crustal magma plumbing system during the build-up to the 22-ka caldera-forming eruption of Santorini (Greece). Bulletin of Volcanology 75, 1–22. Download
Fabbro, G.N., Druitt, T.H., Costa, F., 2017. Storage and eruption of silicic magma across the transition from dominantly effusive to caldera-forming states at an arc volcano (Santorini, Greece). Journal of Petrology 58, 2429–2464. Download
Fabbro, G.N., 2014. The timescales of magmatic processes prior to a caldera-forming eruption (Ph.D.). Université Blaise Pascal, Clermont-Ferrand. Download

A complete caldera cycle at Rabaul, Papua New Guinea

During my postdoctoral fellowship, I studied Rabaul, Papua New Guinea. I found that there was a major change in the shallow plumbing system after the most recent caldera-forming eruption. In the post-caldera system, there is frequent basaltic intrusion, as opposed to andesitic recharge prior to the caldera-forming eruption. This suggests that a silicic reservoir large enough to block the rise of basalt existed before the caldera-forming eruption, but a similar reservoir is not present today under Rabaul. Currently, I am studying the pre-caldera eruptions to track the composition of the recharge and the evolution of the silicic reservoir.

Further reading:

Sizing Up the Next Eruption. Earth Observatory of Singapore Blog, 15 Jul 2016.

Fabbro, G.N., McKee, C.O., Sindang, M.E., Eggins, S., Bouvet de Maisonneuve, C., 2020. Variable mafic recharge across a caldera cycle at Rabaul, Papua New Guinea. Journal of Volcanology and Geothermal Research 393, 106810. Download
McKee, C.O., Fabbro, G.N., 2018. The Talili Pyroclastics eruption sequence: VEI 5 precursor to the seventh century CE caldera-forming event at Rabaul, Papua New Guinea. Bull Volcanol 80, 79. Download