Well - the first thing that actually comes to mind is that I would think any precursors for a quake like the Nisqually quake would be much different that a quake like the San Andreas or a shallow fault would produce.

The next thing is that your question assumes that we are predicting quakes... small medium and large... Some have been predicted.

The next thing is its absolutely easier to predict small quakes - especially in california - you could hardly go wrong in many areas given statistics.

If you are basing predictions on local phenomena its difficult to tell because the big ones are so few and far between that its difficult to build a database of precursors (just what Lowell wants us to do). But I think the larger shallow quakes give off some definite signals - whether they be electromagnetic or what and therefore would be easier to detect (probably due to some sort of micro fractures going on). There's a certain feeling I get when we have larger ones here that I haven't found any other explaination for (except that its a quake coming) but we're back to the old probelm of not enough big ones to really tell if my imagination is working overtime.

Canie