Types Of Eruptions Flashcards
Explosive eruptions
Found at convergent plate boundaries
More acidic with Rhyolite acid
High viscosity
Lower temp at eruption
Violent bursting gas bubbles - magma reaches the surfaces
Top cone can be shattered off due to it being highly explosive
Krakatoa, Indonesia
Gas, lava, dust, ash and tephra bombs
Long periods with no activity
Normally steep - sided strato-volcanoes; Caldera
Eg, Kilauea, Hawaii
Effusive eruptions
Divergent plate boundary
Basaltic lava
Low viscosity
High temperature at eruption
Gas bubbles expand freely with limited explosive force
Gas and lava flows
Eg, Mauna 2001 volcano
More frequent And can last for many months
Gently sloping sides
Shield volcanoes
Lava Plateau
Eg, Mauna Loa volcano
Hotspots
A small area of the earths crust where an unusually high heat flow is associated with volcanic activity
Theory suggests that intensive radioactivity in the earths interior creates a huge column of upwelling lava = plume
Most are located away from the plate boundaries
Magma rises a source deep within the mantle
Hawaiian chain and East African Rift Valley
Rift Valley = crack in the earths crust that is found at a divergent plate Margin
Tectonic setting active continental rift zone
See rest of notes
Size and shape of different volcanoes
super volcanoes
Super volcano = erupted more than 1000km3 of material at once
Exists as giant calderas eg, Yellowstone which is 75km across
Caldera = hollow from where large amount of magma explodes at once
High magnitude events
Deduced from extent and depth Of ash layers and there impact on plant, insect and animal species
