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BHASVIC Geography: Tectonic processes and hazards
Terms in this set (74)
This landform occurs when a build up of gas becomes extreme and explodes removing the summit of the cone, leaving a large crater at the summit
The ejection of volcanic debris into the atmosphere can reduce global tempretures and believed to have caused past climate change
Classic volcanic shape, consisting of layers of ash and lava that is usually andesitic
Conservative margin or transform fault
Where two crustal plates slide past eachother. The movement of the plates is parellel to the plate margin
Constructive (divergent) margins
Where tectonic plates move apart, the space between fills with lava creating new parts of the earths surface.
Convergent (destructive) margins
Occurs when an oceanic plate and continental plate move together. The denser oceanic plate moves under the lighter continental plate
The center of the earth, made up from dense rock containing iron and nickle alloys, divided into solid inner and molton outer core
The outer layer of the earth, above the mantle made from silicon, oxygen, potassium and sodium
Development is linked to an improving society, enabling people to achieve their aspirations. It includes the provision of social services, acquisition of economic assets, improved productivity and reducing vulnerability to natural disasters. Low levels of development are closely associated with high levels of risk and vulnerability to natural disasters.
The realisation of a hazard, when it 'causes a significant impact on a vulnerable population' (Degg). The Centre for Research on the Epidemiology of Disasters (CRED) states that a hazard becomes as disaster when: 100 or more people are affected, 10 or more people are killed, and/or
A country or area that is extremely disaster prone for a number of reasons.
Vertical intrusions with horizontal cracks
Core, Mantle, Crust, Lithosphere, Asthenosphere
The location on the Earth's surface that is directly above the earthquake focus, i.e. the point where an earthquake originates.
Extrusive volcanic landforms
Involves two forms of lava: Basaltic lava or, Andesitic and rhyolitic
Mountain ranges that are formed when two of the tectonic plates that make up the Earth's crust push together at their border.
When water is heated by volcanic activity and explodes onto the surface.
The sum of the many ways individuals and institutions, public and private, manage their common affairs. It is a continuing process through which conflicting or diverse interests may be accommodated and co-operative action may be taken. It includes formal institutions and regimes empowered to enforce compliance, as well as informal arrangements that people and institutions have either agreed to or perceive to be in their interest (The Commission on Global Governance, 1995).
A type of igneous rock which is hard, granular and crystalline.
'A perceived natural/geophysical event that has the potential to threaten both life and property.' (Whittow) Yet a geophysical hazard event would not be such without, for example, people at or near its location. That is to say, earthquakes would not be hazards if people did not live in buildings that collapse as a result of ground shaking. Many hazards occur at the interface between natural and human systems.
A point on the surface of the Earth located above a plume of rising magma.
When ground water is heated by volcanic activity and emerges to the surface.
This is the 'focus' point within the ground where the strain energy of the earthquake stored in the rock is first released. The distance between this and the epicentre on the surface is called focal length.
Usually refers to an unfair situation or distribution of assets and resources. It may also be used when people, nations and non-state players (ranging from transnational corporations to international agencies) have different levels of authority, competence and outcomes.
A measure of the ground shaking. It is the ground shaking that causes building damage and collapse, and the loss of life from the hazard.
These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes.
INTRUSIVE VOLCANIC LANDFORMS
landforms formed when magma is forced into the crust and solidified
a line of volcanic islands formed at a destructive plate boundary
L waves (surface waves)
The slowest and closest to the ground waves. Some of these waves shake the ground at right angles to the direction of wave movement and some have a rolling motion.
A mass of igneous rock, typically lens-shaped, that has been intruded between rock strata causing uplift in the shape of a dome
Volcanic mud flows
Slope failure as a result of ground shaking
Magma formed that is low in silica. It's more fluid that allows gas bubbles to expand on the way up to the surface, so preventing sudden explosive activity
A mass of flowing or solidified lava
Formed from fissure eruptions. The lava flows are basaltic in nature so they flow great distances. They are generally flat and featureless.
A phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading
The surface layer of the Earth is a rigid outer shell composed of the crust and upper mantle. It is on average 100 km deep. The lithosphere is always moving, but very slowly, fuelled by rising heat from the mantle which creates convection currents. The distinction between lithosphere and asthenosphere is one of physical strength rather than a difference in physical composition. The lithosphere is broken into huge sections, which are the tectonic plates.
A fault that is not slipping because the frictional resistance on the fault is greater than the shear stress across the fault, that is, it is stuck. Such faults may store strain for extended periods that is eventually released in a large magnitude earthquake when the frictional resistance is eventually overcome. The 2004 Indian Ocean tsunami was the result of a megathrust locked fault (subducting Indian Plate) with strain building up at around 20 mm per year. It generated huge seismic waves and the devastating tsunami.
this is molten rock below the earths crust
this is when iron particles on the sea floor are alligned according to the earths polarity at the time they were erupted from the constructive plate boundary
The magnitude of an earthquake is related to the amount of movement, or displacement, in the fault, which is in turn a measure of energy release. The 2004 earthquake in Indonesia was very large (M = 9.1) because a large vertical displacement (15 m) occurred along a very long fault distance, approximately 1500 km. (Earthquake magnitude is measured at the epicentre, the point on the Earth's surface directly above the hypocentre.)
this is the section of the earth below the crust and is made up of molten and semi molten rocks containing elements such as silicone and oxygen
this is the point at which two plates meet, can be destructive, constructive, conservative or collision
this is the erosion by the sea of the land, it can clearly be seen on the islands of hawaii where the older islands are much smaller than the new islands due to erosion by the sea
measures the intensity of the event and its impact the scale goes from 1 (detected by seismometers but not felt by many people) to 12 (total destruction with the ground seen to shake)
this causes sedimentary rocks surrounding batholiths, sykes and sills to become metamorphic (eg, limestone to marble)
this is an elemeing fopund in the earths core along with iron
The longest continuous features on the surface of the planet, with a total length of 60,000km. In some parts they rise to 3,000m above the ocean floor.
Results from the zone of magma 'locking in' or 'striking' the Earth's magnetic polarity when it cools. Scientists can use this tool to determine historic periods of large-scale tectonic activity through the reconstruction of relative plate motions. They create a geo-timeline.
The lithosphere is divided into a number of segments known as plates. These rigid slabs float on the underlying semi-solid molten mantle and are moved by convection currents within it.
A theory developed more than 60 years ago to explain the large-scale movements of the lithosphere (the outermost layer of the Earth). It was based around the evidence from sea floor spreading and ocean topography, marine magnetic anomalies, paleomagnetism and geomagnetic field reversals. A knowledge of Earth's interior and outer structure is essential for understanding plate techtonics.
Fastest seismic waves that are compressional, vibrating in the direction that they are travelling in.
Very hot (800 degrees centigrade), gas charged, high velocity flows made up of a mixture of gases and tephra.
In the context of hazards and disasters, resilience can be thought of as the ability of a system, community or society exposed to hazards to resist, absorb and recover from the effects of a hazard.
Highly viscous, acidic lava with high SiO2 content
A numerical, logarithmic used to express the magnitude of an earthquake on the basis of seismograph oscillations.
Formed on a divergent plate boundary, where the Earth's crust spreads apart. The valley is often narrow, with steep sides and a flat floor
The exposure of people to a hazardous event. More specifically, it is the probability of a hazard occurring that leads to the loss of lives and/or livelihood.
Shock waves from an earthquake that travel half the speed of Primary waves but are more damaging as they shear the rock side to side
Generated when rocks within 700 km of the Earth's surface come under such stress that they break and become displaced.
Shock waves released by the rupture of rock strata at the focus of an earthqauke. They travel through the rocks and are recorded on a seismograph
Horizontal intrusions of magma along the bedding planes of sediment rock
The process by which water-saturated material can temporarily lose normal strength and behave like a liquid under the pressure of strong shaking. Liquefaction occurs in saturated soils (ones in which the pore space between individual particles is completely filled with water). An earthquake can cause the water pressure to increase to the point where the soil particles can move easily, especially in poorly compacted sand and silt.
Small volcanic areas without cones. Produced by escaping gases
When a denser plate is forced under a lighter one as they collide into each other
These are broad areas where two plates are moving together, often with the thinner, more dense oceanic plate descending beneath a continental plate. The contact between the plates is sometimes called a thrust or megathrust fault. Where the plates are locked together, frictional stress builds. When that stress exceeds a given threshold, a sudden failure occurs along the fault plane that can result in a 'mega-thrust' earthquake, releasing strain energy and radiating seismic waves. It is common for the leading edge to lock under high friction. The locked fault can hold for hundreds of years, building up enormous stress before releasing. The process of strain, stress and failure is referred to as the 'elastic-rebound theory'.
Tectonic hazard profile
A technique used to try to understand the physical characteristics of different types of hazards, for example earthquakes, tsunamis and volcanoes. Hazard profiles can also be used to analyse and assess the same hazards which take place in contrasting locations or at different times. Hazard profiles are developed for each natural hazard and are based on criteria such as frequency, duration and speed of onset.
Any solid material from an eruption e.g. Volcanic bombs, ash particles
A deep crevice at the point of collision at a destructive plate boundary
The word comes from two Japanese words: tsu (port or harbour) and nami (wave or sea). Tsunamis are initiated by undersea earthquakes, landslides, slumps and, sometimes, volcanic eruptions. They are characterised by: low amplitude (wave height), 0.5-5 m, long wavelengths, typically 150-1000 km, fast velocities, up to 600 kph in deep water.
an impact of volcanic activity. Including carbon dioxide, carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine
Associated with eruption events.
landslide due to volcanic activity
A landform that develops around a weakness in the Earth's crust from which molten magma, volcanic rock, and gases are ejected or extruded.
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