This one off Kaohsiung seems to be part of that fault system that runs diagonally (NE to SW), north of Kaohsiung. I think that probably is the same fault system, if not actual fault, that caused the big quake nearly 100 years ago north of Tainan. I can't remember ever experiencing a quake that size in that area when we lived in Kaohsiung. The big ones were always south, near the southern tip of Taiwan, or northeast of Tainan.

interesting case in italy that sounds like a bad movie plot. Several scientists were rounded up and charged with manslaughter for misdiagnosing a spate of earthquake activity. They visited a particular town and told the people there that everything was fine, nothing to worry about, in fact it was good that the ground was releasing its stress in slower bursts.

as little as a few days later, a major quake struck killing dozens of people.
They were found guilty and sentenced to 6 years in jail and fined $1 000 000.
it sounds pretty drastic to be throwing geologists in jail for wrong earthquake predictions - unless they really did stuff up and mis-read the available data.

so what's your opinion on this one? slow build up to the big one, or the releasing of pressure?

though i guess the best, and most scientifically up to date answer is: don't know.
It's not currently possible to predict earthquakes, is it? That's probably what the italian scientist should have stuck with.
note: a bit more research suggests that clusters of small tremors in the one area are in fact a precursor to a major quake %5 of the time.

This was a 5.5, which is nothing if you live in Hualian, but just off the coast of Kaohsiung, it's quite unusual.

This was a major event in that sense. There will almost certainly be more shakes to come in the area.