The most damaging earthquakes . are deep focus result from ductile deformation are shallow focus along faults across the mid-ocean ridges

Deep Focus

Explanation:

A Deep focus earthquakes is one that occurs deeper  beneath the  subduction zone called  Wadati-Benioff zone having  a focus greater than 300 km deep and magnitudes greater than 6, Because of these, they can only be measured using the Moment Magnitude scale which can measure earthquakes with magnitude over 10

Here there is a forceful collision of the  tectonic plates as they slide over each other within the continental and oceanic plates  boundaries causing the release of great energy,with extreme heat and pressure causing the rocks to flow instead of  breaking and faulting of the rocks

Deep focus earthquakes are very dangerous although occurring 20 - 30 years along a fault line are responsible for the many destructive  tsunamis that happen.