Earthquakes & Volcanoes Flashcards
EARTHQUAKES AND VOLCANOES
When was Earth formed?
Earth was formed 4600 million years ago.
How much does the Earth move each year?
Earth is always moving, although often no more than a few millimetres a year.
What forces cause the Earth to move?
The forces causing Earth to move also cause fold mountains to form, create volcanoes, and earthquakes.
What is underneath the Earth’s crust?
The mantle.
The mantle makes up 82% of the volume of the Earth and is 2900 km thick.
What is the state of the mantle?
The mantle is liquid and flows like really hot jam.
What is the outer core composed of?
The outer core is extremely hot liquid.
What was the initial state of the Earth?
At first, Earth was liquid rock.
What happened as the Earth cooled down?
The outer surface hardened to become a thin crust.
How long did it take for the molten surface of Earth to cool down?
It took more than a billion years to form the crust.
What is the state of the inner core?
The inner core is solid.
What is the temperature of the inner core?
The inner core is 5500 °C.
How far is the inner core from the Earth’s surface?
The inner core is 6400 km from the Earth’s surface.
What are tectonic plates?
The Earth’s crust is broken up into enormous pieces called tectonic plates.
How many major tectonic plates are there?
There are 7 major plates.
How do tectonic plates compare in size?
Some tectonic plates are bigger than continents.
What is happening to tectonic plates?
These plates are constantly moving, rubbing against each other, crashing into, or moving away from each other.
What are the edges of tectonic plates called?
The edges of the plates are known as plate boundaries or margins.
Where are most of the world’s volcanoes and earthquakes found?
Most of the world’s volcanoes and earthquakes are found at plate boundaries.
What are volcanoes?
Volcanoes are openings in the Earth’s surface where magma can escape.
Example: Volcanoes can erupt, releasing lava and ash.
What is a trench?
A trench is a deep, narrow depression in the ocean floor.
Example: Trenches are often formed at subduction zones.
What is subduction?
Subduction is the process where one tectonic plate moves under another plate and sinks into the mantle.
What is a zone in geology?
A zone refers to a specific area where geological processes occur, such as a subduction zone.
