article: Oct 4 2006 - Quakes Near Fox Glacier

An interesting sequence of earthquakes occurred south of Fox Glacier township overnight on October 2/3.

The epicentres of the earthquakes near Fox Glacier.

There were 8 earthquakes detected:

• 7:50 pm, magnitude 3.4, 6 km deep
• 8:48 pm, magnitude 4.3, 5 km deep
• 9:16 pm, magnitude 3.1, 10 km deep
• 9:43 pm, magnitude 3.3, <5 km deep
• 10:02 pm, magnitude 4.6, 8 km deep
• 11:29 pm, magnitude 4.4, 8 km deep
• 4:07 am, magnitude 2.7, 4 km deep
• 6:02 am, magnitude 2.9, 6 km deep

As of this morning, we have not recorded any more quakes in the sequence. Our understanding is that these earthquakes, within a few kilometres of the Alpine Fault, are due to the slow, inexorable increase in stress along this major boundary between two continental plates.

Sequences of small earthquakes such as these are not uncommon in the area, and previous episodes have not been immediately followed by a large, damaging quake. There were two magnitude 4.1 events separated by eight hours near Whataroa on April 27 2006, and two other similar sequences have occured in this part of the West Coast in the last five years.