Key Stuff Flashcards
wave types
P waves cause the immediate shock whilst the S wave has a longer wavelength and arrives seconds later.
epicentre
area above ground directly above focus
focus
point underground where the earthquake originates from
seismic scales
- richter scale, from 1-10
- logarithmic
plate movement - earthquakes
when plates are stuck, convection currents
hazards from earthquakes
shockwaves
- (seismic waves), friction and pressure increase when two plates are side by side. stored as potential energy. can’t move, so builds up. when pressure too much, plates move.
- all pressure transferred to kinetic, released + vibrates through ground. further from focus, weaker the shockwaves.
tsunami
- when oceanic crust jolted during eq, all water above displaced. water travels fast, low amplitude. as closer to coast, water shallower, forcing waves to compress into smaller area.
- causes waves to slow down, gain height, making ‘wall’ of water, avg 10ft high
liquefaction
- when soil saturated, vibrations of eq cause act like liquid. soil becomes weaker, more likely to subside when has large weight on it.
landslides/avalanches
- movement in soil/snow causes slope to become unstable. causes huge areas to give way, sending large amount of debris or snow to fall downhill. damages infra and buildings, the env, and poses threat to life.
hotspot
an area of volcanic activity not related to plate boundaries.
- hot magma plumes from mantle rise and burns through weaker parts of crust
- can create volcanoes and islands
- plumes stay in same place but plates continue to move, makes chain of islands (Hawaii)
hazards of volcanoes
lava flows
- can flow quickly or slowly depending on viscosity
- silica makes lava viscous and slow, common in explosive eruptions
lahars
- usually formed from melting ice @ high latitudes
- volcanic material
mudflows
- triggered by violent shaking that eruption brings or meltwater from volcanic heat
glacial floods
- (jokulhaulps) when temps are high from lava, glaciers/ice sheets at high temps melt quickly and large amt of water discharged
tephra
- any rock ejected by volcano
toxic gases
- released in some eruptions, even CO2 can be toxic as it relaces oxygen bcs heavier
acid rain
- when gases e.g. sulphur dioxide are released into atmosphere
volc landslides
- high velocity flows of debris caused when energy from eruption blows apart rocks and other material
- sends it don volcanic slope
nuees ardentes/pyro flows
- clouds of burning hot ash and gas
- collapses down volcano at high speeds
- avg speeds of 60mph, can reach 430
eq (seismic) hazards prevention, prep, mitigation, adptation
prevention
- most cant be prevented
- liquefaction stopped from soil stabilisation
- avalanches prevented from controlled explosions
prep
- eq prone areas like Japan have awareness strategies in place (drop, cover, hold on)
- eq warning systems and tsunami warning systems
- evac plans and training
mitigation
- search and rescue, immediate aid, evac (SR)
- demolishing old.unsafe buildings, rebuilding new eq proof
adaptation
- move away from risk area
- insurance if living in risky area
- eq proof buildings
volcanic hazards prevention, prep, mitigation, adaptation
prevention
- cant be prevented, only by making sure ppl arent near (not building near them)
prep
- monitoring increases notice of eruptions, allowing warnings to be given out
- education on volc in risk areas so ppl know what to do if eruption
- evac procedures planned
- training response teams
mitigation
- intervention of volcano, e.g. concrete blocks to steer lava away from areas at rick
- strengthening buildings at risk of mudflows/ash pileup
- evac and exclusion zones
- emergency aid ad rescue to mitigate health effects
adaptation
- move from risky areas
- change profession so less likely affected by volc hazards
mass movement
the large scale movement of materials on hillslope, caused when stress exerted exceeds internal strength of the hillspole, causing instability
mass movement causes
slope instability:
- may be too saturated, so material gives way (mudslides)
- weathering/erosion weak internal strength until cant bear load (freeze-thaw processes = rockfalls)
- seismic waves trigger rockslides, landslides, mudflows, etc
- human activities add stress to slope/remove strength (deforestation, roots removed, strength lost as soil less cohesive)
MM impact
- buildings destroyed, so homeless, and businesses destroyed (no income, poverty)
- roads blocked, wildlife killed
- important areas 9govt) destroyed
- jobs lost, power outages
MM hazards prevention, prep, mitigation, adaptation
prevention
- reinforcing slope, e.g. bolting, afforestation, netting, pinning, grading
prep
- evac and response plans in place
- early warning systems, monitoring techniques, so starts can be put in place if indication of MM (seismometers)
mitigation
- search and rescue, evac
- steel netting to catch rockfalls
- hazard mapping used to allocate areas for building/monitoring
*adaptation**
- move away from area at rick
- insurance for living in risky area
- less activities which make slopes unstable like agri, skiing, tourism, construction
tropical storm
low pressure, spinning storm with high winds and torrential rain
