Tectonic hazards Flashcards
What is an earthquake?
A sudden and violent period of ground shaking, commonly caused by the sudden movement of rocks within the Earth’s crust.
Where do earthquakes occur?
Mostly at plate margins. Lots around the edge of the Pacific Ocean. Some are human-induced and caused by fracking, mining and oil extraction.
What is a tectonic plate?
A large section of the Earth’s crust.
What is a tectonic plate margin?
The boundary between two tectonic plates.
What is a volcano?
A large, often conical-shaped, landform created over a long period of time by a series of volcanic eruptions.
Where are volcanoes found?
In long belts that correspond to plate margins. Around the edge of the Pacific Ocean (known as the Pacific Ring of Fire). Through the middle of the Atlantic Ocean.
What are the 4 layers of the Earth called?
Crust, mantle, outer core inner core.
What are the features of continental crust?
Cannot sink/be forced into the mantle. Less dense than oceanic. Older than oceanic – most is over 1500 years old. Cannot be remade or destroyed.
What are the features of oceanic crust?
Can sink/be forced into the mantle. Denser than continental. Younger – most is <200 million years old. Can be remade or destroyed.
Name a process that causes plates to move.
Slab pull / Ridge push.
How do plates move at a constructive plate margin?
Apart from/away from one another.
How are earthquakes/volcanoes created at constructive plate margins?
Plates move apart (e.g. North American Plate & Eurasian Plate). Magma forces its way to surface. Magma breaks through overlying crust = earthquakes. On surface, lava cools to form new crust. Repeated eruptions = layers of cooled crust = volcano. Sometimes volcano chains form.
How do plates move at a destructive (C&O) plate margin?
Toward one another.
How are earthquakes/volcanoes created at destructive (continental and oceanic) plate margins?
Plates move toward one another (e.g. Nazca Plate & South American Plate). Trench formed. Dense oceanic subducted under continental = friction = earthquakes. Oceanic melts in mantle, creating viscous magma = rises through surface, forming steep-sided volcanoes. Eruptions are violent and explosive.
How do plates move at a destructive (C&C) plate margin?
Toward one another.
How are earthquakes created at destructive (continental and continental) plate margins?
Plates Destructive (continental & continental). move toward one another (e.g. Indian Plate & Eurasian Plate). No subduction, no magma, no volcanoes. Plates collide = crust gets crumpled, uplifted & folded. Huge pressure builds, eventually released = severe earthquakes.
How do plates move at a conservative plate margin?
Alongside one another.
How are earthquakes created at conservative plate margins?
Plates move alongside one another (e.g. Pacific Plate & North American Plate). No subduction, no magma. Rough edges of plates grind past one another. Get stuck = huge pressure builds up = crumpled crust. Pressure released when plates slip, jerk or shift) = big earthquake, often close to surface, so devastating.
At which plate margins is there no volcanic activity?
Destructive (continental & continental) and conservative.
Which type of plate margin are the Himalayan Mountains sat on?
Conservative plate margin.
When did the New Zealand earthquake occur?
14th November 2016
How powerful was the New Zealand earthquake?
7.8 on the Richter Scale.
Which plate margin caused the New Zealand earthquake?
The Pacific Plate is subducting beneath the Australian Plate - destructive plate margin.
What were the primary effects of the New Zealand earthquake?
2 people died and over 50 people were injured. Tens of thousands of homes were damaged. 60 people were made homeless. The total cost of the damage was around $8.5 billion. Over 200km of road and over 190km of rail line were destroyed.
