1. Volcanic Hazards

2. Geoff Mackley

4. Tephra Collective term for all airborne or groundflowing
pyroclasts including solidified magma.
Tephra is classified according to size:
Bombs: > 64mm diameter
Lapilli 2-6mm diameter
Ash <2mm diameter

5. Lava Shield – Low Viscosity (flows far)
Cone – high Viscosity (explosive, cools quickly)
Not usually a major hazard, flows in channels or is slow enough to move away from it

7. Lava Bomb
Molten rock, ranging in size from stones to house sized boulders. Explode out of cone volcanoes and can travel many miles

8. Pyroclastic Flow
Superheated gas cloud cascades down the mountain at speeds of up to 450 miles per hour

9. Ash
Ash causes many issues. It can destroy engines such as in aeroplanes due to its glass like structure.
It causes breathing difficulties, destroy crops and can collapse roofs

10. Steam
Not usually a major hazard, but can cause ash to be propelled very high and travel greater distances

11. Gas
Mainly CO2 and SO2. Toxic and can kill people, animals and plants

12. Lahar
Ice from the top of a volcano (or heavy rain) mixes with ash to form a raging river of mud that can bury entire towns