Page 103 - Science Course 2 (Book 2)

Mo10-L4a: What is Earthquake?

The magnitude of an earthquake refers to how much energy is released during an earthquake.

Earthquake Magnitudes

Magnitude Average Number per Year Typical Fault Length on Surface Typical Movement on fault

3 >10,000 15 m 1 mm

4 15,000 100 m 5 mm

5 3,000 800 m 3 cm

6 100 6 km 20 cm

7 20 40 km 1 m

8 2 300 km 6 m

Most earthquakes occur at plate boundaries.
Key Concept
A plate boundary is made up of more than one fault What is Earthquake?
and covers a large region.
Where do most earthquakes occur?
Faults are largest where one plate subducts into
the mantle, and the strongest earthquakes occur at
these locations.

Different types of movement occur at the three types
of plate boundaries.
The convergent boundary between the Indian Plate
and the Burma Plate (part of the Eurasian Plate) At a transform boundary, blocks of crust move
ruptured in 2004. horizontally past each other.

The area of the rupture is indicated in green on the Features that cross the fault, such as streams, are
map. Smaller earthquakes have occurred in the shifted both by plate movement and by earthquakes.
purple areas.

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Asthenosphere

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