Table 1 Grain size, deposit density and equivalent tephra loads for pumice, scoria and ash test samples
From: Laboratory tests to understand tephra sliding behaviour on roofs
Tephra type | Wet/Dry | Median grain size | Maximum grain size | Mean deposit density (kg m−3) | Equivalent distributed tephra load (kPa) for test deposit thickness | ||||
|---|---|---|---|---|---|---|---|---|---|
(ϕ) | (mm) | (ϕ) | (mm) | 10 cm | 20 cm | 30 cm | |||
Pumice | Dry | -2.3 | 5 | -4 | 16 | 433 | 0.42 | 0.85 | 1.27 |
Pumice | Wet | -2.3 | 5 | -4 | 16 | 556 | 0.55 | 1.09 | 1.64 |
Scoria | Dry | -2.3 | 5 | -4 | 16 | 1235 | 1.21 | 2.42 | 3.63 |
Scoria | Wet | -2.3 | 5 | -4 | 16 | 1152 | 1.13 | 2.26 | 3.39 |
Ash | Dry | 1.7 | 0.3 | -1 | 2 | 1443 | 1.41 | 2.83 | 4.24 |
Ash | Wet | 1.7 | 0.3 | -1 | 2 | 1574 | 1.54 | 3.09 | 4.63 |