Tectonics Key Terms Flashcards
What is an Aftershock?
A smaller earthquake following the main shock of a large earthquake.
What is Andesite Magma?
Magma with high silica + gas content, which is viscous, sticky and is likely to cause an explosive eruption featuring multiple hazards such as ash, gas, pyroclastic flows, lahars etc.
What is the Asthenosphere?
A semi-fluid layer of the Earth’s mantle located just below the lithosphere, extending from about 100 to 200 km beneath the Earth’s surface.
What is Basaltic Magma?
Magma with low silica + gas content, which is effusive, ‘runny’, flows easily and is likely to cause a gentle eruption featuring just lava flows.
What is the Benioff Zone?
A zone of seismic activity at a destructive plate boundary where oceanic crust is being subducted, characterized by numerous shallow and deep earthquakes.
What is a Collisional Plate Boundary?
A boundary where two continental plates collide and form mountain ranges.
What is a Conservative Plate Boundary?
A boundary where two plates slide past each other horizontally, resulting only in earthquakes.
What is a Constructive Plate Boundary?
A boundary where two plates are moving away from each other, creating new land (e.g. Mid-Atlantic Ridge).
What are Continental Tectonic Plates?
Plates that are primarily composed of granite and form the continents.
What are Convection Currents?
Circular currents in the mantle caused by the magma being heated by radioactive decay in the Earth’s core.
What is the Core?
The innermost layer of the Earth, consisting of the outer core (liquid) and inner core (solid), primarily composed of iron and nickel.
What is the Crust?
Earth’s outermost layer, ranging from about 5 to 70 km in thickness, composed of solid rock.
What is a Destructive Island Arc?
A chain of volcanic islands formed at a destructive plate boundary.
What is a Destructive Plate Boundary?
A boundary where two plates are moving towards each other, and one is forced to subduct beneath the other.
What is an Earthquake?
When accumulated stress along a fault line is suddenly released, resulting in seismic waves.
What is Elastic Rebound?
The concept explaining how earthquakes are generated and why they often occur repeatedly along the same faults.
What is an Epicentre?
The point on the Earth’s surface directly above the focus of an earthquake.
What is a Fault Line?
A fracture along which sections of crust on either side have moved relative to one another.
What is the Focus (Hypocentre)?
The location within the earth where an earthquake begins.
What is a Jökulhlaup?
A sudden glacial outburst flood caused by the abrupt release of large volumes of meltwater from a subglacial or glacier-dammed lake.
What is a Lahar?
A destructive mudflow on the slopes of a volcano, formed when ash combines with water or glacial meltwater.
What is Lava?
Magma that reaches the Earth’s surface.
What is the Lithosphere?
The rigid outer layer of the Earth, encompassing the crust and the uppermost part of the mantle.
What is Liquefaction?
The process by which water-saturated soils temporarily lose their strength and behave like a liquid during an earthquake.
