This eruption is taking place in an area of frantic seismic activity that is called the Ring of Fire. It is a formation that runs in a circular pattern around the Pacific basin and along the boundaries of where a number of plates collide and either thrust or subduct against each other. It is huge and runs along the coast of North and South America, the Aleutian Islands, the Kuriles, Japan, Marianias Islands, the Philipines, New Guimea and New Zealand.
Along its length are volcanos both active and dormant and innumerable earthquake faults including the infamous San Adraes fault.
The Pacific Ring of Fire at Wikipedia
Ring of Fire- USGS