Hazards

Natural hazards

Naturally occurring physical phenomena caused by geophysical, hydrological, climatological, meteorological or biological

Disaster

The realisation of a hazard, defined by UN as 10+ killed, 100+ injured, a state of emergency declared and a request for international assistance, defined by Swiss Re Insurance as 20+ killed and damage of 16 million US Dollars+

Multi-hazardous environment

A place where two or more hazards occur

Adaption

The attempts made by people to live with hazards, increasing their chances of survival by adjusting their conditions

Fatalism

Viewing the outcome of natural hazards as inevitable, and taking no steps to mitigate it

Domination

Thinking that scientists will be able to understand and prevent destruction from natural hazards

Risk sharing

The community shares the risk and collectively invests to mitigate the impacts of hazards

Perception

The way people view and respond to an event

Risk

The probability of harmful consequences or expected losses from hazards, calculated by frequency or magnitude x vulnerability / capacity to cope or adapt

Vulnerability

The conditions which increase the susceptibility of a community to the impacts of a hazard

Cost / benefit

The advantages/disadvantages of living in an area at risk of a hazard

Preparedness

Pre-arranged measures aimed to reduce the damage of a hazard

Resilience

The ability of a community to survive through and after a hazard

Primary effects

Effects that occur immediately after a disaster, as a result of it

Secondary effects

Long term effects that occur as a result of primary effects

Frequency

The distribution of hazards over time

Integrated risk management

Considering the social, economic, political factors in risk analysis, deciding what actions could be taken after the disaster has occurred 

Magnitude

The size/scale of a disaster

Socio-economic status

The measure of a person’s wealth and position within society

Protection

Modifying buildings/actions people take to protect them from harm before a disaster

Prevention

Weakening a disaster to reduce its impacts, before it reaches people

Community preparedness

The collective knowledge and education a community has to prepare for a disaster

Disaster response curve

Shows how a hazard affects an area, and the time it takes to recover

Park response model

The quality of life compared with the time after a disaster has occured

Disaster management model

Involves hazard assessment, risk management, mitigation, and preparedness

Quality of life

A person’s perception of their life position, in terms of culture and value systems, compared to their expectations and concerns 

Rehabilitation

The restoration of a person’s health or a place to normal after an event

Reconstruction

The restoration of an area

Distribution

The pattern/way something is spread or shared out across an area

Aid

Outside help to an area, can be assisting with resources, finances, services

Evacuation

The removal of people from an area

Fatalities

The amount of deaths

Refugees

A displaced person who cannot return to their home country

Disaster management plan

A formal document containing instructions on the response to unplanned incidents

Primordial

Existing at the beginning of time

Radiogenic

Produced by radioactivity

Crust

The outer shell of the earth

Oceanic crust

6-10km thick, less than 200 million years old, dense, composed of silicon and magnesium (sima)

Continental crust

30-70km thick, over 1500 million years old, less dense, composed of silicon and aluminium

Mantle

2900km thick,

Core

Over 5000 degrees Celsius, consists of the semi liquid outer core made of iron, and the solid inner core made up of an iron-nickel alloy. The outer core spins, creating the magnetic field

Lithosphere

The rigid outer layer of the earth, consists of the crust and upper mantle

Asthenosphere

The part of the mantle found directly beneath the lithosphere

Plate tectonics

The theory that earth’s crust is made up of rigid plates moving slowly and relative towards each other

Sea-floor spreading

At the mid-atlantic ridge, new crust is created moving older crust away, subducting and eventually melting

Wegener

A German climatologist, geologist, geophysicist, meteorologist, and polar researcher 

Magnetic stripes

Alternating rock polarity shown by iron particles in lava aligning with the earth’s magnetic field, creating a stripped pattern on the mid Atlantic ridge

Mid-Atlantic Ridge

A divergent plate boundary located on the floor of the atlantic ocean. Plates move apart, and basaltic lava rises to fill the space

Rift valley

Formed when plates move apart in continental areas, with areas of crust dropping between parallel faults to form the valley

Horst

The upstanding block formed between two parallel rift valleys

Deep sea trench

Formed in subduction zones by the downward movement of the oceanic plate, creating a long, narrow and steep valley

Island arc

Formed at subduction zones, where the descending plate melts due to high temperatures. Magma rises due to being less dense than the surrounding atmosphere, forming volcanoes or a volcanic island after an explosion

Young fold mountains

When continental plates meet, their edges and sediments are forced upwards into fold mountains

Ridge push/gravitational sliding

At constructive boundaries, the ocean ridge has a buoyance effect generated by the upwelling of hot material. Gravity acts down the slope, generating a force acting away from the ridge

Slab pull

At destructive boundaries, the descending plate is pulled down by gravity due to the negative buoyancy of the plate

Convection currents

Heat rising and falling inside the mantle 

Convergent boundary

Consists of subduction zones (o-c/o-o) where the denser plate is subducted, starting to melt at the Benioff zone (100-200km) due to friction and increased heat. At collision zones (c-c) the plates are uplifted as they are of lower density than the asthenosphere beneath

Divergent boundary

Plates move apart from one another, with new oceanic crust formed by magma rising to fill the gap

Transform boundary

Two plates slide past each other, with stresses caused by friction

Hotspot

A concentration of radioactive elements below the crust, causing a plume of magma to rise into the plate above 

Volcano

A rupture in the Earth’s crust containing magma 

Lava

Magma which has reaches the earth’s surface

Lahar

Mud and melted snow/ice combined with ash forms mudflows, up to 100 degrees Celcius and speeds of 200km/h

Volcanic ash

Dust-sized rock particles formed by volcanic eruptions 

Tephra

Rock fragments from 1mm->64mm in diameter ejected from a volcano, ranging from ash to volcanic bombs

Pyroclastic flow/Nuees ardentes

Gas charged, high velocity flows of toxic expanding gas and tephra, at temperatures over 400 degrees Celsius, moving at speeds of 100-100km/h and affecting at least 15km away

Volcanic explosivity index (VEI) 

Logarithmic scale (0-8) measuring the explosiveness of a volcano by the volume of materials produced

Jokulhlaups

The melting of glaciers/ice caps after a volcanic eruption, becoming debris flows

Magma plume

A hot column of magma 

Seismic

The shaking/vibrations of the earth’s crust

Earthquake

An intense shaking motion caused by a pressure release from stressed rocks

Focus

The place and depth of where the earthquake originates

Epicentre

The point on the earth’s surface above the epicentre

Shallow focus

An earthquake originating between 0 and 70 km deep beneath the Earth

Intermediate focus

An earthquake originating between 70 - 300 km deep beneath the Earth

Deep focus

An earthquake originating between 300 - 700 km deep beneath the Earth 

Retrofit

Modifying buildings to be more resistant to seismic activity  

Tsunami

Giant sea waves generated by shallow-focus underwater earthquakes, violent volcanic eruptions, underwater debris slides and landslides into the sea

Richter scale

A logarithmic scale of the strength of earthquakes

Liquefaction

Saturated, unconsolidated material converting and acting like a liquid during an earthquake

Moment magnitude scale (MMS)

A measure of an earthquake's magnitude, compared to its seismic moment

Primary effects

Effects that occur immediately during a hazard

Secondary effects

Effects that occur as a result of primary effects

Mercalli scale

Measures the intensity of shaking produced by an earthquake

Ground rupture

The displacement of the Earth’s surface along the line of a fault

Seismic gap

An area that has been without seismic activity for twenty years

Land-use planning

Regulating the use of land near areas at risk of natural hazards to minimise destruction

Tsuanmi drill

A practise for the steps to take when a tsunami occurs

Tsunami evacuation routes

The directions out of an area that needs to be cleared due to an incoming tsunami 

Tropical revolving storm

A tropical storm spun by the Coriolis 

Tropical disturbance

The first stage in a developing hurricane, with winds below 23 miles per hour 

Tropical storm

An intense low pressure weather system, formed between the tropics when ocean temperatures are above 26 degrees Celsius and causes heavy thunderstorms when reaching land 

Hurricane

Referred to in the Caribbean Sea/Gulf of Mexico area, where 11% of tropical storms occur 

Typhoon

Referred to in southeast Asia, where 1/3 of tropical storms occur 

Cyclone

Referred to in the Arabian Sea/Bay of Bengal area, where 8% of tropical storms occur 

Storm surge

A rapid rise in sea level caused due to the wind of a tropical storm 

Eyewall

Surrounds the eye of the tropical storm, where winds are the strongest and rainfall is the heaviest 

Convergence

Where northeast trade winds meet southeast trade winds

Saffir-Simpson scale

A 1-5 scale of tropical storm intensity based on the maximum sustained wind speed

Hurricane/Cyclone drill 

A practise for the steps to take if a strong tropical storm approached the area, allowing people to prepare evacuating and sheltering