Geography A Level Edexcel: Topic Structures (Topic 1: Tectonic Processes…
Geography A Level Edexcel:
Topic 1: Tectonic Processes and Hazards
Enquiry question 2:
Why do some tectonic hazards
develop into disasters?
Tectonic hazard profiles are
important to an understanding of
contrasting hazard impacts,
vulnerability and resilience.
b. Comparing the characteristics of earthquakes, volcanoes and
tsunamis (magnitude, speed of onset and areal extent,
duration, frequency, spatial predictability) through hazard
a. The magnitude and intensity of tectonic hazards is measured
using different scales (Mercalli, Moment Magnitude Scale
(MMS) and Volcanic Explosivity Index (VEI)).
c. Profiles of earthquake, volcano and tsunami events showing
the severity of social and economic impact in developed,
emerging and developing countries. (4)
b. Governance (P: local and national government) and
geographical factors (population density,
isolation/accessibility, degree of urbanisation) influence
vulnerability and a community’s resilience.
c. Contrasting hazard events in developed, emerging and
developing countries to show the interaction of physical
factors and the significance of context in influencing the scale
of disaster. (5)
a. Inequality of access to education, housing, healthcare and
income opportunities can influence vulnerability and
be explained by
b. The Pressure and Release model (PAR) and the complex
inter-relationships between the hazard and its wider context.
c. The social and economic impacts of tectonic hazards (volcanic
eruptions, earthquakes and tsunamis) on the people,
economy and environment of contrasting locations in the
developed, emerging and developing world.
a. Definition of a natural hazard and a disaster, the importance
of vulnerability and a community’s threshold for resilience,
the hazard risk equation.
Enquiry question 3:
How successful is the management of
tectonic hazards and disasters?
c. The concept of a multiple-hazard zone and how linked
hydrometeorological hazards sometimes contribute to a
tectonic disaster ( the Philippines)
b. Tectonic mega-disasters can have regional or even global
significance in terms of economic and human impacts.
( 2004 Asian tsunami, 2010 Eyafjallajokull eruption in
Iceland (global interdependence) and 2011 Japanese tsunami
a. Tectonic disaster trends since 1960 (number of deaths,
numbers affected, level of economic damage) in the context
of overall disaster trends. (6); research into the accuracy and
reliability of the data to interpret complex trends.
be used to
b. The importance of different stages in the hazard management
cycle (response, recovery, mitigation, preparedness).
(P: role of emergency planners)
c. Use of Park’s Model to compare the response curve of hazard
events, comparing areas at different stages of development.
a. Prediction and forecasting (P: role of scientists) accuracy
depend on the type and location of the tectonic hazard.
1.9 Tectonic hazard
impacts can be
managed by a
vary in their
b. Strategies to modify vulnerability and resilience include hitech
monitoring, prediction, education, community
preparedness and adaptation. (F: models forecasting
disaster impacts with and without modification)
c. Strategies to modify loss include emergency, short and longer
term aid and insurance (P: role of NGOs and insurers) and
the actions of affected communities themselves.
a. Strategies to modify the event include land-use zoning,
hazard – resistant design and engineering defences as well as
diversion of lava flows. (P: role of planners, engineers) (7)
Enquiry Question 1:
Why are some locations more at risk from
c. Physical processes impact on the magnitude and type of
volcanic eruption, and earthquake magnitude and focal depth
b. The operation of these processes at different plate margins
(destructive, constructive, collision and transform). (2)
a. The theory of plate tectonics and its key elements (the
earth’s internal structure, mantle convection,
palaeomagnetism and sea floor spreading, subduction and
slab pull). :
the causes of
b. Volcanoes cause lava flows, pyroclastic flows, ash falls, gas
eruptions, and secondary hazards (lahars, jökulhlaups).
c. Tsunamis can be caused by sub-marine earthquakes at
subduction zones as a result of sea-bed and water column
a. Earthquake waves (P, S and L waves) cause crustal
fracturing, ground shaking and secondary hazards
(liquefaction and landslides).
can be explained
a. global distribution and causes of earthquakes, volcanic
eruptions and tsunamis. :ocean:
Distribution of Earthquakes
Occur when energy stored in elastically drained rocks is released. These earthquakes can be generated by bomb blasts, volcanic eruptions and sudden slippage.
b. distribution of plate boundaries resulting from divergent,
convergent and conservative plate movements (oceanic,
continental and combined situations). :warning:
form when two continental plates collide. Neither plate is forced under the other, and so both are forced up and form fold mountains.
constructive plate boundary
, sometimes called a divergent plate margin, occurs when plates move apart. Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.
An example of a constructive plate boundary is the mid-Atlantic Ridge.
destructive plate boundary
, or convergent plate margin occurs when oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger earthquakes. Magma rises up through cracks and erupts onto the surface.
An example of a destructive plate boundary is where the Nazca plate is forced under the South American Plate.
A conservative plate boundary
occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds.
Friction is eventually overcome and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.
This occurs at the San Andreas Fault in California.
c. The causes of intra-plate earthquakes, and volcanoes
associated with hot spots from mantle plumes. :volcano: