TOPIC 1 HAZARDS - A LEVEL GEOGRAPHY - EDEXCEL

Seismic hazard

the intensity of shaking and ground disruption by earthquakes that can be expected over the long term at some specified location

Volcanic hazard

any potentially dangerous volcanic process

(ex: lava flows, pyroclastic flows, ash fallout, lahars)

Subduction

The process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.

Mantle Plume

a column of very hot rock rising up through the mantle

Intra-Plate Earthquake

An earthquake that occurs in the interior of a tectonic plate

Oceanic Fracture Zone (OFZ)

A belt of activity through the oceans along the mid-ocean ridges, coming ashore in Africa, the Red Sea, the Dead Sea rift and California.

Continental Fracture Zone (CFZ)

A belt of activity following the mountain ranges from Spain, via the Alps, to the Middle East, the Himalayas to the East Indies and then circumscribing the Pacific.

Convection

The transfer of thermal energy by the circulation or movement of a liquid or gas

Slab pull

the pulling of a tectonic plate as its edge subducts deep into the mantle

Palaeomagnetism

the study of past changes in the earth's magnetic field

Hypocentre

The focus point within the ground where the strain energy of the earthquake stored in the rock is first released

Locked Fault

A fault that is not slipping because frictional resistance on the fault is greater than the shear stress across the fault (it is stuck). Such faults may store strain for extended periods that is eventually released in an earthquake when frictional resistance is overcome.

Sea Floor Spreading

the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies

Basalt

A dark, dense, igneous rock with a fine texture, found in oceanic crust

Andesite

a dark, fine-grained, brown or grayish volcanic rock that is intermediate in composition between rhyolite and basalt.

Rhyolite

A light-brown to gray, fine-grained extrusive igneous rock with a felsic composition. The extrusive equivalent of granite.

Benioff Zone

A zone of earthquake activity along the upper portion of a sinking plate, as it scrapes past the opposing plate, in a subduction zone.

Primary and Secondary Waves

Two types of body waves produced by earthquakes

Love waves (Q)

shake the surface side-to-side.

Liquefaction

The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud

Water Displacement Column

An area of sea water from surface to sea floor that is displaced

Oblique reverse faults

The upthrust of the crust resulting from an earthquake

Magnitude

Measure of the energy released during an earthquake

Intensity

The amount of energy per second carried through a unit area by a wave.

Epicentre

the point on the Earth's surface directly above the focus of an earthquake

Tsunami

A huge destructive wave (especially one caused by an earthquake)

Pyroclastic flows

scalding avalanche of ash and hot, toxic expanding gas, traveling very fast down the flank of a volcano

Tephra

rock fragments and particles ejected by a volcanic eruption.

Lahars

a destructive mudflow on the slopes of a volcano.

Jökulhlaups

Type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. ( yo-KOOL-lahp)

Hazard

A danger or risk.

Disaster

A sudden catastrophic event in which people are injured and killed and property is destroyed

Mega-disaster

a catastrophe that threatens or overwhelms an area's capacity to get people to safety, treat casualties, protect infrastructure, and control panic

Socio-economic

of, relating to, or involving a combination of social and economic factors

Spatial predictability

the area or place where a hazard or event may take place with some certainty

Dynamic pressures

Processes that result from the root causes of vulnerability that can quickly change if the root causes are addressed

Risk

a situation involving exposure to danger

Resilience

the personal strength that helps most people cope with stress and recover from adversity and even trauma

Community adaptation

Cooperation within communities to change people's way of life so as to reduce tectonic hazard impacts.

Hazard vulnerability

The capacity of a person or group to anticipate, cope with, resist and recover from the impact of a natural hazard

Mercalli

A scale that rates earthquakes according to their intensity and how much damage they cause at a particular place, 1-10

Moment MagnitudeS

a more precise measure of earthquake magnitude than the Richter scale, which is derived from the amount of displacement that occurs along a fault zone and estimates the energy released by an earthquake.

Tectonic hazard profiles

are used to understand and compare the physical characteristics and processes of the three different types of tectonic hazard.

Mitigation

the action of reducing the severity, seriousness, or painfulness of something

Multiple-hazard zones

Places where a number of physical hazards combine to create an increased level of risk for the country and its population.

Focal depth

distance between focus and epicenter

Inequality

An imbalance

Governance

The process of governing

Players

individuals and groups who are interested in and affected by a decision-making process

Rapid and slow onset

How fast or slow an hazardous event occurs.

Hydro-meteorological

Natural hazards caused by climate processes (including droughts, floods, hurricanes and storms)

Climatological

weather related

Geophysical

The study of physical properties of the earth

Hydrological

cycle of water, the movement of water and its transformation between the gaseous (vapour), liquid, and solid forms.

Meteorological

having to do with the weather or climate

Zonation

the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species.

Land use zoning

A mapping exercise by local government that decides how land should be used (housing, industry, health, education, etc.) in the various parts of a town or city.

Modification

the act of making something different

Retro-fitting

the process of making older structures more earthquake resistant

Hazard Management

Managing a hazard

Modifying the loss

Insurance, emergency relief and disaster aid

Just in time (JIT)

An inventory-management approach in which supplies arrive just when needed for production or resale

TNC

transnational corporation

Disaster hotspot

A country or area that is extremely disaster prone for a number of reasons.

oceanic crust

thinner, more dense, younger crust making ocean floor

continetal crust

Solid, outer layers of the earth, including the rocks of the continents. - Thicker, less dense, older

sea-floor spreading

the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies

The core

Center of the earth

Inner core

A dense sphere of solid iron and nickel at the center of Earth

outer core

A layer of molten iron and nickel that surrounds the inner core of Earth

Crust

The thin and solid outermost layer of the Earth above the mantle

Destructive margins

-plates move together, oceanic sub-ducts under continental crust

-friction causes Earthquakes

-melting plate causes Volcanic activity

Constructive margin

Where two plates are moving away from each other.

Magma rises from the mantle to fill the gap and cools, creating new crust.

Conservative margin

where two plates try to slide past each other slowly. Quite often, the two plates stick and pressure builds up; the release of this pressure creates a severe earthquake. There are no volcanic eruptions.

Plate Tectonic Theory

the theory that the lithosphere is broken up into large plates that move and then rejoin; considered the unifying theory of geology - 7 major plate

mid-ocean ridge

An undersea mountain chain where new ocean floor is produced; a divergent plate boundary.

rift valleys

a large elongated depression with steep walls formed by the downward displacement of a block of the earth's surface between nearly parallel faults or fault systems.

fault

A break in the earth's crust

GIS

Geographic Information System, A computer system that stores, organizes, analyzes, and displays geographic data.

Seismometer

measures and records ground motion and can be used to determine the distance seismic waves travel

aftershock

An earthquake that occurs after a larger earthquake in the same area

Landslides and Avalanches

the shaking of ground can cause L and A on steep hills or mts which causes damage

Lava flow

the area covered by lava as it pours out of a volcano's vent

Gas eruptions

Magma contains disolved gases that are released into the atmosphere during a volcanic eruption

Volcanic Explosivity Index (VEI)

An intensity scale that rates a volcano's destructiveness and explosive power on the amount of matter it ejects during an eruption.

water column

The vertical column of seawater that extends from the surface to the bottom

Lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle.

Risk equation

Risk = hazard x vulnerability / capacity to cope

Pressure and release (PAR) model

Looks at the underlying causes of a disaster, based on the idea that a disaster occurs when two opposing forces interact: on one side the processes that create vulnerability and on the other the hazard itself

High tech monitoring

hazard-adaptation strategy which uses technology to predict and increase response during hazard events

ridge push

the process in which new material at a ridge or rift pushes older material aside, moving the tectonic plates away from the ridge

fold mountains

mountains that form where two plates collide and force layers of rock into folds

trench

A deep, steep-sided canyon in the ocean floor.

Accretion Wedge

The accumulation of material at the point of subduction.

batholiths

A mass of rock formed when a large body of magma cools inside the crust

crustal fracturing

Caused by primary waves - the result of increased stress on solid rocks

composite volcano

a large, steep-sided volcano that results from explosive eruptions of andesitic and rhyolitic lavas along convergent plate boundaries

Shield volcanoes

a broad, domed volcano with gently sloping sides, characteristic of the eruption of fluid, basaltic lava. - quiet eruptions

Adaptation

Is changes in the ways of doing things so future hazards have less impacts.

resilience

The capacity to cope / withstand effects of the natural disaster.