Vanuatu has a large quake a week ago and the aftershocks are still rolling. Bit the big one today so far is the 6.8 that rolled the Banda sea. This area like Vanuatu is a ‘U’ shaped bend in the fault, which is a subduction zone fault.
These u shaped zones are under a lot of stress. With both a strong push to the side and subduction on both sides causing upward push and this causes great stress and so earthquakes. The whole system of faults along the Indo-Australian north edge and the quakes they produce along the whole of Indonesia, PNG, and on around the fault zone to Fiji is powered by the steady north push by the Indo-Australian plate.
After the relative calm of the last few days this number of quakes today was expected. And the number of them at Vanuatu is also not unexpected as it has recently had a couple of large quakes and aftershocks will continue.
- Vanuatu still shaking (echlinm.wordpress.com)
- Banda Sea earthquake reignites seismic swarm near Vanuatu (via The Extinction Protocol: 2012 and beyond) (loopysexpressions.wordpress.com)