K A AN Sample 1- KE4-40 SU5B SU2B UJ1B 5- KE4-25 KE5-35 KE5-38 KA1-4 RA1 PA1 PA4 KA2 KA10 BA2 AN7 3 30 A Depth (cm) 85 41 48 90 21 30 25 35 38 45

Code pa pa pa pa pa pa pa pa rpl rpl pf pf pf ig ig ig ig

Oxide (wt. %) 6 67. SiO2 6. 66.98 68.78 69.33 65.83 68.87 68.53 69.22 69.54 68.57 68.03 69.74 73.61 67.08 72.48 68.89 20 64 0. 0.8 TiO2 0.85 0.81 0.71 0.87 0.70 0.67 0.67 0.71 0.74 0.72 0.73 0.26 0.34 0.38 0.42 67 1 1 16. Al2O3 5. 15.79 14.43 15.02 16.77 15.04 15.44 15.43 14.52 14.69 15.04 14.58 16.69 22.84 16.14 17.31 00 03 3. 5.0 Fe2O3 5.03 5.87 5.36 5.09 3.95 4.02 3.90 3.72 3.86 4.00 3.73 2.53 3.48 3.30 3.67 88 0 0. 0.1 MnO 0.14 0.09 0.16 0.13 0.12 0.12 0.12 0.13 0.14 0.12 0.12 0.06 0.04 0.11 0.10 12 5 1. 1.2 MgO 1.44 0.82 0.91 1.26 0.99 0.98 0.91 0.98 1.01 1.08 0.92 0.64 0.27 0.85 0.46 31 9 3. 2.8 CaO 3.39 4.40 3.20 3.40 2.81 2.50 2.38 2.64 2.95 3.19 2.66 0.68 0.48 0.76 2.34 92 4 5. 4.2 Na2O 4.21 2.27 2.22 3.85 4.47 4.33 4.85 5.27 4.85 4.72 5.02 2.35 2.32 1.95 3.98 50 0 2. 2.0 K2O 1.99 1.87 2.39 1.85 2.23 2.37 2.31 2.41 2.31 2.15 2.33 3.19 3.10 4.00 2.80 29 9 0. 0.2 P2O5 0.20 0.14 0.15 0.23 0.19 0.17 0.18 0.17 0.17 0.18 0.15 0.04 0.04 0.04 0.03 18 2

9 99. Total 9. 100.03 99.49 99.44 99.27 99.38 99.13 99.98 100.08 99.28 99.24 99.99 100.06 100.00 100.00 100.00 78 55

ESM2 Major element composition of 1883 Krakatau pyroclastic deposits, compared to other major pyroclastic deposits around Sunda Strait. Sample codes: pa are pumiceous ash interbedded with 1883 tsunami deposits; rpl are rounded pumice lapilli (1883 tsunami deposits); pf are 1883 pyroclastic flow deposits sampled in Panjang (samples PA1 and PA4) and Rakata (sample RA1) islands, and defined as white rhyodacite by Mandeville et al. (1996a); ig are ignimbrites from Rajabasa volcano (Eastern Sumatra: samples KA2, KA10 and BA2) and Danau caldera (Western Java: sample AN7). KA samples are from Kalianda (Fig. 6), KE5 from Gubug Garam (Fig. 7), KE4 from Lampong PLTU (Fig. 8), SU5 from Sumur (Fig. 3), SU2 from Cigorondong, UJ from Ujung Kulon (Fig. 2), and AN from Cikoneng River, near Anyer (Fig. 5b). Values recalculated to volatile-free oxide totals of 100 wt.%.