Topic 2 Dynamics of Earth's Crust
Topic 2 Dynamics of Earth's Crust
2.1 Plate tectonics and seismic activity
Nature of science:
Wegener's ideas about continental drift were initially explored and then dismissed for several decades by the scientific community? In the 1960s a revision of his ideas brought about a paradigm shift in the scientific community.
Use of models as representations of the real world
Understandings:
Earth has several moving plates outlined by intense earthquake activity at the edges of plates
Mechanisms have been proposed for the movement of plates
Movements include subduction, seafloor spreading, mountain building
Plate movement over a hotspot has created the Emperor seamounts and the Hawaiian islands
Marine trenches, island arcs, rift valleys, seamounts, mid-ocean ridges result from seismic activities due to plate tectonics
Applications and skills:
Skill: modeling plate actions
Skill: mapping plates and their movements on a globe
Skill: determining an earthquake epicenter from seismic readings
Limitations of models
2.2 Evidence of tectonics
Nature of science:
Looking for patterns, trends and discrepancies
Importance of verification among data sets in the building of a theory
Understandings:
Evidence includes magnetic anomalies, temperature data, earthquake epicenter profiles, etc.
Use of hotspot data in the Pacific to measure rate and direction of movements of the Pacific Plate
Applications and skills:
Skill: examining data from edges of plates
Data sets collected by magnetometers, seismographs, bathythermographs and core samplings can be analysed
Skill: analysing of the velocity of plate movement
2.3 Tsunamis
Nature of science:
Developing tools that can accurately detect and thereby be used to predict the magnitude and timing of an arriving tsunamis has been an engineering challenge.
Understandings:
Tsunamis are generated by subsidence earthquakes, as well as submarine landslides and meteorites large enough to displace a large volume of water as well as volcanic eruptions and calving glaciers
The wave characteristics change as the wave crosses the ocean and approaches shore. (in open oceans a wave may be less than a meter high with a period of 10 to 30 min and a wavelength of 100 - 200 km, but at a coast it may be 100 m high with shorter wavelengths as the energy of the wave is compressed into a smaller column of water.)
Tsunamis are detected by DART ® with tsunameters that communicate with surface buoys and satellite communication
Subduction tsunamis that occur near a coastline cause subsidence of the shore which complicates the effect of the tsunamis
Applications and skills:
Skill: Use archival data to calculate the dimensions of a named tsunami.
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