It's not particularly surprising we had one here. We've been having them continuously since the 2010 quake. The difference with this one is that it has caused a tsunami. I can hear the tsunami warnings going off from where I am, and the streets are filled with people moving inland.

I wonder if it ever will be. I have heard stories of entire colonies of ants emerging from their underground burrows a day before a major earthquake occurs. I also wonder if animals can sense impending lightning strikes.

It's half a meter on the sea level. Probably the same on the crust. Some quakes result in several meters of shifts, some only a foot or two.

The scientific consensus is that it won't. While gravity does cause the moon to pull on the earth's crust, the moon is not going to be closer enough than normal to have any effect.

We've already had about 500 aftershocks that register 4.0 or higher.

What? If it's a full moon (of which a supermoon is a subset) then the Moon and Sun are directly opposite each other, and spring tides are due. These tides also affect the land masses, although a usual rise of 6 inches isn't much. But this supermoon was closer than most, otherwise it wasn't a supermoon, and gravitational attraction increases as the inverse of the square of distance, so it could have been "the straw that broke the camels back" so to speak.

I wouldn't rely on gut feeling. There's decades and decades of seismic data that shows absolutely no link between proximity of the moon and increased seismic activity. I've read a few articles on the subject recently. The idea of a supermoon causing earthquakes isn't new, and people have been postulating the possibility for decades. There have been lots of studies done and not a single one has even found data that will show correlation, let alone causation.

What Arthur suggests is possible - the moon does still exert some force on us (even if insignificant under normal circumstances), but if a whole lot of other factors came together at the right time, the extra pull from the moon might be enough to do something that it couldn't alone.

Again however, if there was a link, it probably would have been found by now (especially when the timing of the movement of the sun and moon is so well known). Such a link is the holy grail to seismologists and they've been looking for it for centuries.

edit:

Consider that even with the perfect alignment, gravitational effects might only increase by 100%, but a 10,000% increase would be needed to have any noticeable effects.

nb. I made the percentages up, but you get the idea I hope.

edit 2:

I was watching an interview with a seismologist last week after the earthquake and someone asked him about the supermoon. The look on his face was what you'd expect from archaeologists when people start asking them about the Pyramids being docking platforms for alien spacecraft.

It doesn't really matter, the spring tides are equal on both sides of the earth regardless of if it's a full moon or new moon. During a new moon, the gravitational attraction is all in one direction, but the far side of the earth is attracted less than average due to increased distance, so the tides still occur on the far side. Almost like a centrifugal force trying to whip stuff off the far side.

Their fault line system is connected to ours. It's not uncommon for quakes in one zone to be quickly followed by quakes in the other.