option D - geophysical hazards

Question 1

secondary hazards

Answer 1

• secondary effects of a natural hazard
• e.g: tsunamis, landslides, lahars

Question 2

magnitude

Answer 2

size of a geophysical event

Question 3

constructive boundary

Answer 3

• move away from each other; lava seeps through the crack to form new land
• e.g: south american and african plate (mid atlantic ridge)

Question 4

destructive boundary

Answer 4

• subduction zone: denser plate subducts
• e.g: south american and nazca plate

Question 5

transform boundary

Answer 5

• two plates that slide laterally against one another
• no volcanic activity
• e.g: san andreas fault

Question 6

ring of fire

Answer 6

zone around the pacific ocean where volcanoes are most common

Question 7

epicentre

Answer 7

• where the earthquake is felt the most on land
• directly above the focus

Question 8

vulnerable population

Answer 8

infants, disabled and elderly people

Question 9

focus

Answer 9

where the earthquake occurs deep in the ground

Question 10

hot spots

Answer 10

thin areas in the earth’s crust where magma can escape

Question 11

composite volcanoes

Answer 11

• along destructive plate margins
• pyramid shaped (has side vents)
• e.g: merapi, 2023

Question 12

shield volcanoes

Answer 12

• along constructive plate margins (iceland) and where there are hot spots (hawaiian islands)
• dome shaped
• e.g: kilawea, hawaii

Question 13

convection cells

Answer 13

slow motion of the earth’s solid rock by convection currents (surface dragged by friction)

Question 14

human triggers - landslides

Answer 14

• lack of vegetation
• extraction of materials from the soil

Question 15

cinder cone volcano

Answer 15

• cone shaped
• e.g: paracutin volcano, mexico

Question 16

factors affecting slope stability

Answer 16

• gravity
• slope angle
• pore pressure

Question 17

factors increasing shear stress

Answer 17

• removal of underlying support (undercutting, construction)
• transient stresses (earthquakes, mining)

Question 18

earthquake case study

Answer 18

• haiti (near port-au-prince) –> 7.0 magnitude –> 2010
• 230,000 deaths
• 300,000 injured
• 1.5 million left homeless
• $8 billion in economic losses (over 100% of haiti’s GDP)

factors increasing vulnerability:
- poverty
- poor housing construction
- limited disaster preparedness

Question 19

volcano case study

Answer 19

• eyjafjallajökull iceland 2010
• located on mid-atlantic ridge –> constructive plate boundary
• eruption was explosive, sending ash plume 10km high
• disruption to european air travel - over 100,000 flights cancelled affecting 10 million travelers
• 800 people evacuated from vicinity

Question 20

landslide case study

Answer 20

• guinsaugon (philippines) –> 2006
• trigger: several weeks of heavy rainfall
• estimated 1,000-1,500 deaths
• 300 homes destroyed

factors increasing vulnerability:
- lack of warning systems
- poverty and lack of education
- poor infrastructure

Question 21

pre-event management strategies

Answer 21

• land-use zoning
• public education and awareness
• improved building codes + construction
• early warning systems

Question 22

post-event management strategies

Answer 22

• providing emergency shelter, food, water, and medical aid
• temporary housing solutions
• monitoring for secondary hazards