Today brought the quake we were expecting in New Zealand, which happened in one of the few parts of the zone that would create little to no damage. We hope this is the tail of the earthquake storm that has been moving down the Fiji to New Zealand trenches and fault lines for the last year. At 5.3 it is in the range of magnitude of the damaging quakes at Christchurch but being in the Cook Straight and at a depth of 59 km little to no damage was caused and this must make the people of the region relieved.
While this is what we have been looking for a quake in the 5 to 5.5 magnitude n this central area of New Zealand. After the quake just off the tip of the north island last month you may recall I said that the people of New Zealand should be prepared and have their emergency kits ready. This quake fulfils that prediction that does not mean that more quakes, after shocks or larger quakes, won’t happen. But the chances of large damaging quakes is reduced for now. (But then the last time I said that things went bad for Japan.)
This quake was 53 km down, and the crust at the average is about 40, so this was in the subducted section of the Pacific plate that this quake happened, and has a whole other plate above it and so the energy is dissipated and diminished so no tsunami or damaging shaking above. But just because this quake has happened and was not damaging doesn’t mean we take our eyes off of this zone or that it’s not interesting. It is close to this point that the Pacific plate changes from being subducted beneath the Indo-Australian plate in the north island to riding over and subducting the Indo-Australian plate in the south island. Why and how this happened is one of the many things we are trying to understand about these islands. Echo soundings from this quake will give us more data and help unlock these questions.
(Data and image from USGS.gov)