Focus on the Kermadec Trench

Map of Kermadec Arc north of the North Island ...

Image via Wikipedia

The fault from the center of New Zealand north to Tonga is a two part deep trench. And in the last week it has been the center of a lot of activity, earthquake wise. The range of magnitudes goes as high as a 7 in the Kermadec islands but is now moving the activity southward along the trench but including tremours as far north as the Tonga islands and even Fiji which is just around the corner of this fault system.

The theory that earthquakes can release pressure in one location of a fault and so transfer that stress to adjacent faults or locations on the same fault would indicate that the stress on the fault on the south end is building and may cause larger earthquakes closer to New Zealand. The deep part of the trench doesn’t reach New Zealand so I am hoping this earthquake storm, if it is one should not reach the north island but could set off a large quake closer than the 7.6 from July 6 (2011).

Checking the data from the earthquake databases shows that this is always an active fault. In most cases the quakes follow a pattern, a large quake at the north end of the fault then the quakes progressing southward. The quakes start with a 7 and it’s aftershocks then a 7 again further south and it’s after shocks going a bit southward then another 7 and its aftershocks progressing southward until they get to NewZealand. There have been 5 8+ quakes in the last 25 years but they have mostly been at the 15 to 20 degrees south range with 2 at 28 south. If these patterns of a series of 4 large quakes are earthquake storms then this current one started 2 years ago with a 8.1 in Fiji area and has gotten to the lower middle portion of the zone. The larger quakes (7 or higher) rarely get as far south as New Zealand’s north island but they do once in a while as shown by last years 7 at -43.52 171.83.

Another interesting and troubling trend lately has been that quakes are setting off volcanoes and this area is rather volcanic. Quakes in Africa, South America and the Atlantic have all set off volcanoes, some in days, others in as long as a year; that is a possibility that the south Pacific must be watching for.

This trend of the earthquake activity moving south is worrisome and should not be ignored but will in all likelihood not cause any heavy damage if it does work its way down to New Zealand, although it will be interesting to watch.


About echlinm

Computer Programmer/Systems Analyst/Hacker S31
This entry was posted in Earth Science, Earthquake and tagged , , , , , , , . Bookmark the permalink.

6 Responses to Focus on the Kermadec Trench

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