The correct answer is option 4: the point on the surface directly above where the rupture along the fault zone occurs.

Option 1 is incorrect because the earthquake epicenter is not determined by the location of the seismograph. The seismograph is a device used to measure and record ground motions during an earthquake, but it does not determine the epicenter.

Option 2 is incorrect because the point within the Earth where the movement along the fault occurs is known as the focus or hypocenter, not the epicenter. The epicenter is on the Earth`s surface, directly above the focus or hypocenter.

Option 3 is incorrect because the epicenter is not necessarily the approximate center of a group of related earthquakes. It is the point on the Earth`s surface where the seismic waves radiate out from the focus or hypocenter.

Therefore, the correct answer is option 4: the point on the surface directly above where the rupture along the fault zone occurs. This is the location where the earthquake is typically felt the strongest.