2B: Effects and responses to tectonic hazards Flashcards
Where are volcanoes found?
Wherever magma rises to the surface
Three substances that volcanoes emit?
Lava
Pyroclastic material
Gases
Acid lava characteristics
High silica content
Temp around 700 degrees
Viscous
associated with destructive plate boundaries
Basic lava characteristics
Low silica content
Temp around 1200 degrees
Non-viscous
Forms basalt
associated with hot spots + tensional margin
Why acid lava eruptions are more dangerous than basic lava?
Pockets of gas
Gas does not escape the pockets
When it explodes its sticky
Shield volcano
domed volcano with gentle sloping sides
Mauna Loa
Composite cone
conical volcano built up by layers
What is VEI
Volcanic explosivity index.
from 0 to 8
Each step up from 2 is a 10x increase
Earthquake definition
sudden ground movements
occurring when crustal rock accumulates strain - then moves along a fault
Energy released from seismic waves
Focus
The point within the crust where the earthquake rupture starts
Epicentre
The point on the ground directly above the focus
Richter scale
measures magnitude and scale of earhtquake
Mercalli scale
Measures the devastation of an earthquake on a 12 point scale
A subjective assessment
Primary impacts of strong earthquake
Surface ruptures
Collapsed buildings
Damaged infrastructure
Secondary impacts of a strong earthquake
Fire
Landslides
Tsunamis
Liquefaction
Disease and famine
