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topic 1 - tectonic processes and hazard - Coggle Diagram
topic 1 - tectonic processes and hazard
convection currents
1 - heat from inner core through mantle into asthenosphere
2 - hot magma rises as less dense with heat
3 - magma cools further away and starts to sink again
4 - cooler magma reheats and rise again
5 - this loop is convection currents
earth's structure
crust/lithosphere
- thinnest, less dense, lightest - up to 70 km thick
mantle/asthenosphere
- semi-molten, convection currents, 700km to 2890km
outer core
- dense, semi-molten, 2890km to 5150km
inner core
- over 5150km, solid 1) primordial heat left over 2) radiogenic energy from radioactive decay
plate boundaries
constructive
<-- -->
continental/continental
rift valleys, earthquakes, volcanoes
oceanic/oceanic
ocean ridges, earthquakes, volcanoes
conservative
(side/side)
earthquakes
destructive
--> <--
continental/continental
fold mountains, earthquakes
oceanic/oceanic
ocean trenches, island arcs, earthquakes, volcanoes
continental/oceanic
fold mounntains, earthquakes, volcanoes
plate movement
mantle convection
- convection currents push and pull the plates
slab pull
- oceanic crust submerges into mantle and drags the rest of the plate with it
however not fully understood how they move
earthquakes
plates don't fit perfectly together, so when they rub against eachother friction is made
when plates are stuck convection currents keep pushing, building up pressure
this pressure can't be maintained so the plate give way and the pressure is released
this then releases a jolt and this movement is the
seismic waves
epicentre
- area above ground directly above the focus
focus
- point underground the earthquake comes from
seismic waves
primary waves
- travel through solids, compressional, vibrates in direction of travel, travels at 4-8km/s
secondary waves
- vibrate at right angles to direction of travel, travels only through solid rock, 2.5-4km/hr
love
- near to ground surface, rolling motion producing vertical ground movement, 2-6km/hr
rayleigh
- vertical and horizontal displacement, compressional, 1-5km/hr
secondary
and
love
are most destruction as large amplitudes
primary impacts
ground shaking, surface rupture, infrastructure collapse
secondary impacts
soil liquefaction, landslides, tsunamis (usually in subduction zones/convergent plate boundaries), disease
Volcanoes
primary impacts
lava flows, pyroclastic flows, tephra/ash flows, volcanic gasses
secondary impacts
lahars, jokulhaup, acid rain
classification and theories of tectonic events
disaster
- a serious disruption in the functioning of a community/society and the area can't cope with its own losses
risk
- risk = hazard x vulnerability / capacity to cope