I've got no idea. You'd have to ask an expert, but most of them are either too scared to say anything in case they are wrong or busy writing pointless academic papers to insure they keep getting funded.
I do know that there is an interconnecting web of fault lines and it would seem reasonable that the recent burst of activity was associated with the Chi Chi fault line in some way
On the other hand, cluster earthquake activity is a common phenomenon in Hualien and hasn't escalated to a major earthquake there in recent times.
The 'funny' thing about earthquakes is that in themselves, they are actually pretty much harmless - it's the man-made structures that fall down that cause all the death and destruction (ok, tsunamis and landslides are the exceptions)