Tectonics Flashcards
Aseismic Buildings
Buildings designed to withstand or minimise destruction during an earthquake.
Lithosphere
The lithosphere is the solid, outer part of Earth.
Asthenosphere
A zone of Earth’s mantle lies beneath the lithosphere and is believed to be much hotter and fluid-like.
Continental Drift
A theory stating that the Earth’s continents have been joined together and have moved away from each other at different times in the Earth’s history. The theory was first proposed by Alfred Wegener in 1912.
What processes are involved in continental drift?
Slab pull.
Ridge push.
Convection currents.
Convection currents
Liquid rock is heated and rises. When it reaches the crust it is forced sideways as often it can not pass through the crust. The friction between the convection current and the crust causes the tectonic plate to move. The liquid rock then sinks back towards the core as it cools. The process then repeats.
Slab pull
Occurs when older, denser tectonic plates sink into the mantle at subduction zones. As these older sections of plates sink, newer and less dense sections of plates are pulled along behind. Sinking in one place leads to plates moving apart in other places.
Ridge push
Gravitational force that causes a plate to move away from the crest of an ocean ridge, and into a subduction zone.
Focus
The point beneath Earth’s surface where pressure/seismic energy is released.
Epicentre
The point on the Earth’s surface directly above the focus of an earthquake (the origin of the earthquake).
Hot Spot Volcanoes
Intraplatal volcanoes exist over a magma plume from the Earth’s mantle.
(Hawaii and La Palma).
Jokulhlaup
Sudden glacial floods are caused by a glacier on top or near a volcano, melting due to the heat from the eruption.
Lahar
Destructive mudflows on the slopes of a volcano.
Pyroclastic Flow
A mixture of gases and rock fragments, at high temperatures travelling at rapid speeds.
Mid-ocean Ridge
Occur along constructive plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
