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When is a Fault "Active"

Geologists believe that if a fault shows evidence of having moved at least once in the past 100,000 years, it should be regarded as a potential source of earthquakes. If it has moved at least once in the past 5000 years, then it should be considered a potential source of damaging earthquakes to any settlement within a radius of 50km. Once a major fault has formed, future earthquakes are generated along the same line, and after hundreds of thousands or million of years of movement, increasingly large vertical and horizontal displacements of land occur. Repeated earthquakes and their associated fault movements have formed the major mountain ranges of New Zealand.

awatere

The Awatere Fault cuts a clear line across the hills. It last ruptured in the 1848 Marlborough Earthquake.