Physical Features

Seismic gaps are

  1. plate boundaries having no volcanic activity
  2. parts of plate boundaries in oceans where tsunamis occur frequently
  3. sections of plate boundaries that have not ruptured in the recent past
  4. sections of plate boundaries that have ruptured repeatedly in the recent past

Answer

A seismic gap is a segment of an active fault known to produce significant earthquakes, that has not slipped in an unusually long time when compared with other segments along the same structure.

The correct option is B.