On March 19th, the moon is full and is also at its closest point to Earth on its elliptical orbit. There is a great deal of fuss being generated about this, and this astronomical event is already being blamed for the Japanese earthquake and tsunami even though it's still five days from happening.
Why does the full moon matter? Because a full moon means the Earth is directly between the moon and the sun. However, the moon's gravity and the difference in distance over its orbit is just not enough to raise so much as the hairs on the back of your neck. There is no measurable physical effect of this event, and certainly no measurable effect a week before it even happens.
The full moon has psychological effects on people. That has been recognised for a long time, hence the term 'lunatic' and the association of all kinds of weird behaviours with the full moon.
The moon influences tides, we know this for certain.
But plate tectonics? Moving water around is one thing, moving rock is quite another. The moon just doesn't have the density to exert that kind of pull on subterranean rocks. If it did, we'd all feel lighter and weigh measurably less during one of these events due to the moon's gravity counteracting part of Earth's. If it can shift continental plates it will certainly affect little organic masses like us. It doesn't.
So no, next week's supermoon did not cause last week's disaster.
It is, however, a great photo opportunity if the clouds are kind to us.