sometimes
-
There are better ways to detect where plate boundaries. If you're talking specifically about where the epicenter of an earthquake is, what geologists do is use a triangular mapping system to pinpoint the location on the surface of the earth. They will have several earthquake detecting systems in the ground and when an earthquake happens the systems will pick up on the waves the earthquake generates. By seeing which wave hits which system first they can determine where the earthquake is. However there needs to be at least three systems for it to work properly.
-
Absolutely not. Tidal waves are created by the gravitational influence of the Moon and the Sun on Earth. Tidal waves are not generated by seismic activity.