No, a significant change in topography does not necessarily imply that an area will be seismically active. However, with few exceptions, it does mean that the area was once subjected to processes that would have produced earthquakes in some way. When these processes become inactive, the topography they built stays behind, gradually eroding back down (or in the case of a basin, filling up). This explains why some prominent topographic features are lacking in earthquake activity at present.
What explains those areas where major earthquake activity occurs, but no notable topography exists? You may have already guessed the more obvious explanation: pure strike-slip faulting. If no vertical motion of the surrounding rocks is created through either compression or extension (i.e. by pure strike-slip movement), then it is possible that even a large fault will produce very little in the way of topographic changes. This rarely happens for the length of an entire fault, since few fault zones have absolutely no bends or step-overs -- both of which produce noticable topographic features -- or strike across perfectly flat topography.
The more common explanation for high seismicity in an area of little to no topography is the burial or partial burial of faults by sediment. This can be seen in several places in southern California. Basins and valleys, sometimes formed by faulting, may have active strike-slip faults running through them, in the rocks of the valley floor. However, the flow of dirt and debris into these basins is sometimes so large that it completely overwhelms the minor topographic changes created by the fault's motion. Despite the activity that may be going on deep below the valley fill, we see nothing at the surface. A good analogy to this is the topography beneath the ocean, much of which, off the coast of southern California at least, is created by faulting. Only in a few places do these topographic changes stick up above the surface of the water, but that doesn't mean that the ocean bottom everywhere else is flat -- it is simply hidden by the material above it.