Earthquakes

Earthquakes & volcanic activity
Earthquakes often occur in volcanic regions and are cause there, both by tectonic faults and the movement of magma in volcanoes.

Size and frequency of occurrence
500,000 earthquakes a year;
Since 1900, there have been an avarage of 18 major earthquakes and one great earthquake per year;
Most of the world’s eartquakes take place in horseshoe-shaped zone called the circum-Pacific seismic belt.
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