Hi Chris. I was using the term “major” as a generic description of a quake that could be bigger then a breadbox. A major quake is any quake between M=7.0 and M=7.9. A great quake is M=8.0 to M=8.9 and a megaquake is between M=9.0 and M=9.9.

The fault that runs through the Island of Sumatra is another source for a pretty big quake, but again there is no way of knowing when it will occur.

As for the quake in March of 2005 I’m not sure if you could call it an aftershock or a main event. Its location near the end of the 1861 rupture would suggest it was a main event.

I think Kerry Siehs chief concern was the area of the 2004 quake simply because it was the next segment of the fault that could fail and was in line with the 1833 and 1861 quakes. At any rate this puts the areas of the 1833 and 1861 quakes as the next most probable location for a major, or great quake. Take Care…Don in creepy town