Release of water shakes Pacific plate at depth

A team of seismologists analyzing the data from 671 earthquakes that occurred between 30 and 280 miles beneath the Earth’s surface in the Pacific Plate as it descended into the Tonga Trench were surprised to find a zone of intense earthquake activity in the downgoing slab. The pattern of the activity along the slab provided strong evidence that the earthquakes are sparked by the release of water at depth.
Geology News — ScienceDaily