Topic 1 - Hazardous Earth Flashcards
Define after shocks
aftershocks follow an earthquake as the fault ‘settles’ into its new position
What is Andesitic Lava?
a thick and sticky lava erupted from composite volcanoes
What is the asthenosphere?
Part of the Earths’ mantle. It is a hot, semi-molten layer that lies beneath the tectonic plates
What are base isolators?
flexible pads on which a building is built to help it withstand earthquakes by isolating it from the moving ground
Define Basaltic lava
lava that is low in silica, fluid that flows easily
What is the collision zone?
where two tectonic plates collide – forming mountains like the Himalayas
What is a composite volcano?
a steep-sided volcano that is made up of a variety of materials, such as lava and ash
Define a conservative plate boundary
where two plates are sliding alongside each other
What is continental crust?
thick crust forming the Earth’s land masses
What are convection currents?
circular current of heat in the mantle
What happens at a convergent plate boundary?
where two plates are moving towards each other, resulting in one plate sinking beneath the other
Define the core of the earth
the central part of the Earth’s structure, made up of a solid inner and a liquid outer core
What is the Coriolis effect?
the deflection of air movement by the Earth’s rotation
Define the term crater
a depression in the ground formed by volcanic activity, often circular in shape with steep sides
What is cross-bracing on a building?
a system of supports built diagonally inside buildings to help them withstand earthquakes
Define the crust
the outer layer of the Earth
Describe a cumulonimbus cloud
very tall, dense clouds that often bring heavy rain, thunder and lightning
Define a divergent plate boundary
where two plates are moving apart
Define an earthquake
a sudden and often violent shift in the rocks forming the Earth’s crust, which is felt at the surface
Define the term effusive
a type of eruption where runny lava flows steadily out of a fissure or vent
Define the epicentre
the point at the Earth’s surface directly above an earthquake’s focus
Define an escarpment
a continuous line of steep slopes above a gentle dip slope caused by the erosion of alternate strata
What does the term ‘eye’ mean in a tropical storm
the centre of a tropical cyclone; an area of clear conditions created by air converging at the centre of the storm and then sinking
What is the eye wall
a thick bank of cloud around the eye with high wind speeds and heavy rain
Define the term fault
a fracture or break in rocks
What does the term fissure mean?
a crack in the crust which lava comes out of
What is the focus of an earthquake?
the point in the Earth’s crust where the earthquake begins
What is a fold mountain?
long, high mountain range formed by upfolding of sediments
Define geothermal
heat from inside the earth
What is the global circulation model?
a theory that explains how the atmosphere operates in a series of three cells each side of the equator.
What is the hadley cell?
a circulation cell near the Equator responsible for storms at the Equator and desert belts north and south of the Equator
What is a hazard?
a short-term event that threatens lives and property
What is a hotspot?
a section of the Earth’s crust where plumes of magma rise, weakening the crust; these are usually away from plate boundaries
Define an ice core
a section of ice drilled from a glacier showing the layers of ice created over time
Define jet stream
a fast-moving current of air in the upper atmosphere
What is a lahar?
a mudflow resulting from ash mixing with melting ice or water - a secondary hazard of a volcano
define landfall
the point at which a tropical storm reaches land
Define lava
molten rock that erupts from a volcano or fissure
What is a lava bomb?
fragments of molten lava blown out of a volcano during an eruption
What is liquefaction?
the process where sediments shaken by an earthquake behave like a liquid and so lose strength
Define Lithosphere
Make up of the Earth’s crust and upper mantle
Define magma
semi-molten rock found in the mantle layer of the Earth
Define magma chamber
an underground pool of magma that feeds a volcano
Define magnitude
the quantifiable size of an event or piece of data (i.e earthquake)
Define the mantle
the dense, mostly solid layer of the Earth between the outer core and the crust
What is the mid-ocean ridge?
an underwater mountain range formed by diverging tectonic plates
What is the Milankovitch cycle?
a long-term change in the Earth’s orbit that causes natural climate change
Define milibar
a unit of measurement of atmospheric pressure - 1000 millibars is approximately ‘average’ pressure
What is moment magnitude scale?
the scale usually used today to measure the strength of an earthquake
Define the term monsoon
a seasonal prevailing wind in South and South East Asia; it blows from the south-west between May and September (the wet monsoon), and from the north-east between October and April (the dry monsoon)
What is oceanic crust?
the Earth’s crust beneath the oceans, thinner but denser than continental crust
What is an ocean trench?
deep section of the ocean, usually where an oceanic plate is sinking below a continental plate
Define the term pangea
a supercontinent continent of the whole land area of the globe before being split up by continental drift.
What is a plate boundary?
the margin at which two plates meet
Define the term plumes
upwelling of molten rock through the asthenosphere to the lithosphere
What is a polar cell?
a circulation cell furthest from the Equator that brings cold air south towards the UK
Define prediction
attempt to forecast an event (where and when it will happen) based on current knowledge
Define preparation
organising activities and drills so that people know what to do if an earthquake happens
What is a primary hazard?
a hazard which is the direct result of an earthquake, volcano or cyclone
What is a primary impact?
the immediate effects of a natural hazard, caused directly by it
Define the term protection
constructing buildings so that they are safe to live in and will not collapse
What is pyroclastic flow?
a lethal hot mixture of broken rocks and gases that races down the sides of a volcano
What is the quaternary period?
the current period of geological time
What is radioactive decay?
the process where natural radioactive materials in the Earth’s rocks break down, giving out energy and heat as they do so
Define residual heat
the heat in the Earth’s core remaining from its formation
What is the richter scale?
a numerical scale showing the magnitude of an earthquake based on readings from a seismometer
Define rift valley
a long, narrow valley created between two parallel faults caused by divergent tectonic plates
What is the saffir-simpson scale?
scale that classifies hurricanes into five different categories according to their wind strength
Define secondary hazard
a hazard which occurs indirectly as a result of the primary impacts of a hazard
Define secondary imapct
the knock-on, or indirect, effects of a volcanic eruption or earthquake that take place on a longer timescale
Define seismometer
an instrument that measures movements of the ground, especially during earthquakes
What is a shield volcano?
a broad volcano that is mostly made up of lava
What is a shockwave?
seismic wave generated by an earthquake that passes through the Earth’s crust
What is the source area?
the region in which a tropical storm first forms
What is a storm surge?
a rapid rise in the level of the sea caused by low pressure and strong winds
Define subduction
the process of one plate sinking beneath another
What is the subduction zone?
the zone where one tectonic plate sinks (subducts) under another
Define a supervolcano
a colossal volcano that erupts at least 1000 km3 of material
What is a tectonic plate?
large areas of rock that make up the Earth’s crust
Define the term tectonic processes
the theory related to the seismic movement of the Earth’s plates
What are the three P’s
the collective term for prediction, protection and preparation
Define tiltmeter
an instrument that measures small changes in the angle of the ground or buildings
What is the track
the path followed by a tropical cyclone
What are tree rings?
marks on the inside of tree’s trunk that show individual growing seasons. The thickness of the rings varies depending on climatic conditions during the seasons
What is a trench?
a long, deep depression in the ocean floor formed in the subduction zone between two tectonic plates
Define the term tropical cyclone
a weather system that forms over the ocean in tropical areas and can produce high winds and heavy rain
Describe the tropics of Cancer and Capricorn
23½ degrees north and south of the Equator; they are the farthest point north and south where the Sun’s rays strike the Earth’s surface at 90 degrees
What is a vent?
an opening on the Earth’s surface which emits lava or gas
Define the term viscosity
the fluidity of a lava (or other substance) - how ‘sticky’ it is
Define the term vog
volcanic smog caused by sulphur dioxide mixing with sunlight, oxygen, water and dust particles
Define a volcano
cone-shaped mountain formed by surface eruptions of magma from inside the Earth
What is a volcanologist?
a geologist who studies volcanoes
Define Inter-tropical Convergence Zone
Inter-tropical Convergence Zone a belt of low pressure around the Earth just north and south of the Equator, where warm, moist trade winds come together
What are isobars?
isobars lines on a weather map that indicate areas of equal atmospheric pressure
Define latitude
how far north or south a location on the Earths surface is from the Equator, measured in degrees
Describe a cirrus cloud
a type of cloud that appears as thin wisp-like formations at high altitude
Define climate
the average weather conditions of an area occurring over many years
Define climate change
a long-term change in the Earth’s climate, especially changes in temperature
What is a climate graph?
a graph showing the average temperature and rainfall at a particular place
What is the diurnal temperature range?
the difference between the highest day temperature and lowest night temperature
What is the enhanced greenhouse effect?
the trapping of heat radiation around the Earth by excess greenhouse gases produced through human activity
Define ferrell cell
circulation cell that brings warm air north towards the UK
Define global warming
a rise in average global temperatures
Define greenhouse gases
gases like carbon dioxide and methane that trap heat around the earth, leading to global warming
Define precipitation
water vapour condensed in the atmosphere which falls as rain, snow, sleet or hail
Define relief
the height and shape of the land
What is remote sensing?
using satellites or aerial photography to provide information on land use over large areas
Define stratosphere
the layer of air 10-50km above the earths surface
