Lava Flows and Volcanic Tephra. - Coggle Diagram
Lava Flows and Volcanic Tephra.
Angular grains, so highly abrasive.
2 mm in diameter
Dense when wet (forms cement-like mixture)
Can ignite fires at close enough distances to eruption centre.
Roof collapse after 30 cm of deposit.
Air craft hazard
Breathing difficulties (for humans and livestock)
Formed by partial collapse of the eruption column.
Flows are mostly gaseous with small amounts of solid material (which tends to be fine grained)
Able to flow uphill over ridges as well as over water.
Deposits are likely to be found only on one flank of a volcano.
Deposits are planar or cross bedded.
Formed by complete collapse of eruption column
Dense flows that contain a high proportion of solid material which varies in size from ash to blocks.
Gravity driven so follow low-lying topography such as valleys.
Deposits can be found around the entire circumference of a volcano.
Deposits are poorly sorted
Formed large amounts of water (heavy rain, glacial melts etc) mix with loose volcanic debris.
They can travel for 10's of km and happen a long time after an eruption, creating significant risk.
Deposits are poorly sorted, with clasts that range form boulders all the way down to ash particles (which may end up from clay or silt).