Table 1 Field characteristics of the pre-Historical Holocene explosive eruption deposits
Unit | Eruption Age (yrs BP) | Number of localities | Thickness (cm) | Max. Pumice (cm) | Max. lithic (cm) | Description |
|---|---|---|---|---|---|---|
Z | 360 ± 60–4240 ± 110 | 24 | 30 - > 200 | – | – | Massive ash layer – series surge and ash fall deposits |
Y | 4460 ± 40 | 27 | 48–140 | 17 | 7 | Tephra fall |
X | 4380 ± 80–4520 ± 60 | 19 | 2–12 | – | – | Ash-rich surge |
W | 4480 ± 60–4540 ± 60 | 23 | 8–28 | 6 | 5 | Tephra fall |
V | 4540 ± 60–4640 ± 60 | 25 | 2–15 | – | – | Ash-rich surge |
U | 4740 ± 40–4790 ± 100 | 27 | 15–20 | 4 | 2 | Tephra fall |
T | 4810 ± 50–5390 ± 50 | 26 | 5–100 | – | – | 3 subunits comprising tephra fall bounded by surge |
S | 5430 ± 50–5500 ± 60 | 22 | 12–46 | 4.5 | 2 | 2–3 fall deposits interbedded with PDC |
R | 5550 ± 80–5790 ± 50 | 21 | 2–29 | – | – | Ash-rich surge |
Q | 5850 ± 60–5980 ± 50 | 18 | 25–50 | – | – | 2 tephra fall deposits separated by surge |
P | 5980 ± 50–6150 ± 40 | 20 | 6–42 | 9 | 6 | Tephra fall |
O | 6150 ± 40–6950 ± 50 | 20 | 30 - > 100 | – | – | Massive ash layer – series surge and ash fall deposits |
N | 6950 ± 50–7070 ± 60 | 16 | 12–60 | 17 | 12 | Tephra fall |
M | 7070 ± 60–7520 ± 50 | 15 | 12–100 | – | – | Ash-rich deposit with lenses of tephra fall |
L | 7520 ± 50–7530 ± 80 | 16 | 4–50 | 6 | 3 | Tephra fall |
K | 7530 ± 80–7710 ± 60 | 10 | 38 - > 100 | – | – | Series discontinuous interbedded PDC and fall |
J | 7750 ± 60–7760 ± 50 | 8 | 7–15 | 6 | 3 | Tephra fall |
H | 9770 ± 60–10,310 ± 50 | 9 | 15–42 | 5 | 2 | Tephra fall |
F | 11,840 ± 70–12,080 ± 150 | 6 | 3–90 | 5 | 8 | Tephra fall |
D | 12,460 ± 60–13,350 ± 130 | 9 | 32–180 | 6.5 | 5 | Tephra fall |