OP, does the break up of the Indo-Australian tectonic plate (see the information provided below) also factor into the "triangular" plate tectonic theory that you have put forward?

Newly published findings shed light on the relationship between two large (8.6 and 8.2 magnitude) quakes in the Indian Ocean that happened this past April 11th and the ongoing break up of the Indo-Australian plate.

These research findings have just been published in the most recent (Sept 26th) issue of Nature (the International Journal of Science), which is a VERY well recognized scientific journal.

The title of the research article published in Nature is:

Unusual Indian Ocean earthquakes hint at tectonic breakup

The article is subtitled:

April 2012 quakes occurred away from plate edges, suggesting formation of a new boundary.

Here are excerpts of the research article:

A pair of massive earthquakes that rocked the Indian Ocean on 11 April 2012 may signal the latest step in the formation of a new plate boundary within Earth’s surface.

Geological stresses rending the Indo-Australian plate apart are likely to have caused the magnitude-8.6 and magnitude-8.2 quakes, which broke along numerous faults and unleashed aftershocks for 6 days afterwards, according to three papers published online today in Nature.

Seismologists have suspected since the 1980s that the Indo-Australian plate may be breaking up. But the 11 April earthquakes represent “the most spectacular example” of that process in action, says Matthias Delescluse, a geophysicist at the Ecole Normale Supérieure in Paris and lead author of the first paper1. Worldwide, “it’s the clearest example of newly formed plate boundaries,” he says.

...the Australian portion [of the Indo-Australian plate forged ahead, creating twisting tensions that are splitting the plate apart in the Indian Ocean.

...the magnitude-9.1 tremor in 2004 that unleashed a massive tsunami across the Indian Ocean, and another quake in 2005 — probably triggered the 2012 event by adding to pent-up stresses in the plate’s middle region.

However, the first 11 April event defied expectations as the largest strike-slip earthquake on record, and one of the strongest to occur away from any conventional plate boundaries.

...accumulated stresses spread over the plate’s interior broke free in the first 11 April event, resulting in one of the most complex fault patterns ever observed. Unlike most earthquakes that shake along a single fault, this one ruptured along four faults, one of which slipped as much as 20–30 metres.

...scientists found that for six days following the event, earthquakes of magnitude 5.5 and greater occurred at almost five times their normal rate all around the world.

[link to www.nature.com]