If you match up the volcanoes with the tetonic plates and the directions the plates move. the activity seems to indicate that there is major expansion on the American edge of the Pacific plate and the southern edge of the Australian plate driving that plate and the Pacific plate via the Philippine plate into the Eurasian plate in a sort of pincers move.

The expansion on the Pacific plate edge is also driving the Cocos and Nazca plates in the opposite direction of which the earthquakes and volcanoes along the Central American and South American land masses would be symptomatic.

There's likely volcanic activity occuring at the point of expansion also but it's underwater.