Geophysical Hazards Flashcards
(16 cards)
What are the major tectonic plates?
Major Plates – Pacific, Eurasian, North American, African, Indo-Australian, South American, Antarctic.
What are the types of tectonic plates?
Convergent, Divergent and Transform
Convergent plate?
Convergent (Destructive & Collision): they collide into each other – earthquakes, volcanoes, mountains.
Divergent plate?
Divergent (Constructive) they move away from each other – Mid-ocean ridges, new crust.
Transform?
Transform (Conservative) they slide past eachother– Earthquakes, no volcanoes.
Basic knowledge of the convection currents?
Convection Currents: Hot magma rises, cools, and sinks, moving plates.
What are the two types of crust?
Oceanic crust and continental crust.
What is the oceanic crust?
Oceanic Crust (Sima)
Thinner (~7 km thick).
Denser (made of basalt).
Younger (constantly being recycled at subduction zones).
What is the continentalcrust?
Continental Crust (Sial)
Thicker (~30–70 km thick).
Less dense (made of granite).
Older (some parts are over 4 billion years old).
What are the four layers of earth?
The crust is the outermost solid layer, consisting of both oceanic and continental crust.
Below the crust lies the mantle, a thick layer of hot, viscous rock.
The outer core is a liquid layer surrounding the inner core.
The innermost layer is the solid inner core.
What is a fault line?
A fault line refers to a fracture or zone of fractures in the Earth’s crust where rock masses have slipped past each other.
These movements along the fault plane release energy as seismic waves, causing the shaking experienced as an earthquake.
What is the focus in an earthquake?
In an earthquake, the focus is the point within the earth where the earthquake’s rupture or initial break begins.
What are seismic waves?
Seismic waves are vibrations that travel through the Earth and are caused by events like earthquakes.
They transmit energy outward from the source, causing the Earth to shake.
What are the two main types of seismic waves?
Two main types of seismic waves are P waves (primary waves) and S waves (secondary waves).
What is the epicentre?
The epicenter of an earthquake is the point on the Earth’s surface directly above the focus where the earthquake originates beneath the surface.
