tectonic plates
No. It is all related to an earthquake.
earthquake and related tsunami.
a tsunami
A volcanic eruption can cause an earthquake and an earthquake underwater can cause a tsunami.
There are tsunamis and there are tsunami trains. A tsunami is generated by an underwater earthquake. A new tsunami has to wait for a new earthquake. It is not uncommon for any earthquake to be followed by one or more aftershocks within a matter of hours or days, so a new tsunami can result similarly. Since earthquake behavior is notoriously unpredictable, so is tsunami generation. A single tsunami results in a series of waves with periods ranging from minutes to hours. This is called the tsunami "wave train". There is more information in the related links.
The Earthquake occurred before the tsunami as it is what caused the tsunami.
No. A tsunami is a giant ocean wave. A tsunami can be caused by an earthquake, but they are completely different things.
An earthquake happened, which triggered the tsunami.
There was a tsunami, but it was triggered by a volcanic eruption, not an earthquake.
Earthquake
The epicenter for the magnitude 9.0 earthquake in Japan on March 11, 2011 was located at 38.297°N, 142.372°E. The tsunami originated from the epicenter. For a map showing how the tsunami traveled around the world see related question below.