Hazardous Environments

Natural hazard

An extreme natural event that *could* damage people or property

Natural disaster

A natural hazard that actually damages people (100 or more people affected)

Types of hazard classifications

meteorological, tectonic, climatological

Hazard risk

the probability / danger of being affected by a natural hazard (increased by poverty, high population density, climate change etc.)

Vulnerability

How susceptible a community is to the damaging effects of a hazard

Capacity to cope

The ability of a community to manage a disaster

Tropical cyclone

Low pressure system with a wind speed of over 120km/h, found in the tropics. A rotating group of thunderstorms around a central eye.

Conditions required for tropical cyclones

Deep sea warmth over 27 degrees (meaning late summer and in the tropics), low vertical wind shear, circulatory movement of the air aided by the Coriolis effect

Why do tropical cyclones move westward?

Prevailing trade winds moving westwards

Impacts of tropical cyclones

Storm surges, strong winds, torrential rain

Primary effects

The immediate short-term impacts of a natural disaster

Secondary effects

Long-term impacts of a disaster

Case study: impacts of Typhoon Haiyan

2013. Primary: 100K killed in Tacloban City and 90% of all buildings destroyed. Secondary: $8bn in damages, increased spread of disease & reduction in tourism

Constructive margin

Plates move apart as magma rises up. Shallow earthquakes + shield volcanoes (Mid-Atlantic ridge)

Destructive margin

Oceanic v. Continental crust: deep powerful earthquakes, deep sea trenches & composite volcanoes (Nazca + South American plates)

Conservative margin

Two plates move parallel to eachother. Deep earthquakes (San Andreas Fault)

Collision margin

Continental v Continental. Creates mountain ranges + deep earthquakes (Himalayas)

Composite volcano

Destructive boundaries. Steep with thick, acidic lava. Very explosive but infrequent, & creates pyroclastic flows with lots of tephra. (Mt. Fuji)

Shield volcano

Constructive boundaries & hotspots. Gently sloping with runny basic lava. Not very explosive but frequent. Creates lahars & lava flows. (Eyjafjallajokull)

Hotspot

A spot on the mantle where heat rises & brings magma up with it, breaking through the surface as a shield volcano.

Focus

Centre of the earthquake underground

Epicentre

Point above the focus

Case Study: Eyjafjallajokull

2011: Volcano erupted + shut down European airspace. 100K flights grounded, & £200mil/day loss in revenue. Kenya lost £3million in perishables

Resilience

the capability to rebuild quickly from disaster

Reasons why people live in hazardous areas

Fertile soils, family ties, religious ties, existing infrastructure, not wealthy enough to move out, nice landscapes, perceived safety

Case Study: Haiti earthquake

2010: magnitude 7 earthquake, killed 220k, resulted in frequent power cuts + looting, increases in disease + reliance on foreign aid

Anti-earthquake building measures

Birdcage steel reinforcements, open areas, base isolators,

Prediction methods

Prediction: GIS, satellite imagery, remote sensing etc.

Prevention methods

Building reinforcements, sea defences, defences.

Nepal Earthquake: prediction + prevention methods

2015: not many: poor country + so did not have abilities

Amatrice earthquake: prediction + prevention methods

2013: some prediction but prevention was poor. Afterwards more earthquake proof building measures implemented.