Global Hazard Patterns Flashcards
name 3 geophysical hazards
earthquakes, tsunamis, volcanoes
which plate boundaries trigger earthquakes?
conservative & destructive
how to destructive plate boundaries cause earthquakes?
- plates move toward/ together
- force of compression
- stresses in crust
- pressure quickly released
- earthquake focus
how do conservative plate boundaries cause earthquakes & give an example of one
- plates slide past each other
- friction & quick releases of tension
- frequent shallow earthquakes
San Andreas Fault
explain the difference between the lithosphere and the asthenosphere
lith = crust asthen = molten zone of rock beneath crust
what 2 main primary hazards do earthquakes cause?
- buildings collapse
2. water pipes burst
what 3 main secondary hazards are caused by earthquakes?
- tsunamis
- landslides
- soil liquefaction
what plate boundaries are volcanoes found on
destructive & constructive & hotspots
give an example of a volcanic destructive plate boundary
ring of fire, pacific ocean
give an example of a volcanic constructive plate boundary
ocean mid-atlantic ridge (iceland)
how does a hotspot create volcanoes & give an example
areas of lithosphere receiving abnormally high heat from aesthenosphere, hawaii island
what is drought dependant on in africa?
inter-tropical convergence zone, if north to south direction disrupted, then food security threatened from drought in Somalia/Ethiopia
what causes drought in australia?
el nino
where does flooding usually occur?
in areas of excessive, monsoon rainfall & cyclones (e.g hawaii in el nino), or where snow melting on mountains adds to swollen river system
where does el nino cause flooding & what is its impact?
- south america
- flooding = disease, destruction infrastructure, insurance costs
where do tropical cyclones usually occur, give example?
- over warm water, 5degrees North or South of equator, Coriolis effect causes circulation of air
- off coast of east asia
how does the philippines geophysical location make it vulnerable to multiple hazards?
- lies within SE Asian typhoon belt
- destructive plate boundary, philippines plate subducting under eurasian plate
- N & E coast faces Pacific ocean
- monsoon climate = flooding
- 7000 islands = difficult to reach & warn
what 4 human factors mean the philippines is vulnerable to the multiple hazards it faces?
- MIC = 2006, GDP: $5000 per capita
- poor people live in high risk coastal areas, exposed to storm surges
- pop density, 2000 per km in Manila, which is at sea-level
- pop growth, 250 000per year in Manila
when did Mt. Pinatubo erupt?
1991
why was the explosion of Mt. Pinatubo so large (5 steps)?
- Philippines plate subducts & melts
- melted magma forms magma chamber
- magma solidifies = solid cap over volcano vent
- pressure builds under cap
- cap ruptures = huge pyroclastic flows & lahars
how many died from the eruption of Mt. Pinatubo?
350
how many were evacuated by US air base before Mt. Pinatubo eruption?
200, 000, although many died after from disease in camps
how many hectares of farmland were destroyed by Mt. Pinatubo eruption in 1991?
80, 000 hectares
what other hazard does the philippines face? Give an example
landslides, Guinsaugon landslide 2006, killed 1150
what triggered the landslide in the philippines in 2006?
2.6 earthquake
give 1 human and physical factor that exacerbated the guinsaugon landslide in the philippines?
human = deforestation, shallow rooted coconut trees, mass movement physical = la nina, caused heavy rain in usually dry month of feb
what plate boundary is the san andreas fault in california?
conservative, slide past each other at different speeds
how many people densely live in california?
40 million
how many major earthquakes have occurred in the last 100 years in Cali?
5
in what year did the 7.9 earthquake take place in San Francisco?
1989
how much cost of damage was caused by the 1989 san francisco earthquake?
$6 billion!
how many homes were destroyed in the san francisco earthquake?
1018 destroyed!
in what year was the 6.7 earthquake in LA?
1994
how many homes were impacted in the Northridge LA earthquake?
9000 homes without water
which rivers are affected by el nino in california?
san gabriel rivers, hillsides deforested so heavy rainfall easy surface run-off
why do la nina droughts cause so many problems for california?
- forest fires mean no trees to protect against rainfall in el nino = landslides
- mediterranean climate is hot already without droughts in summer
how is advection fog caused & impacts california
- cold air offshore meets hot air onshore
- combines with car pollution
- photochemical smog
- sits in basin of california
