We have a two story split level with fireplaces on both floors. The outside brick that 'houses' the flutes and/or the fire box of the upstairs fireplace is pulling apart. The morter in between the bricks is crumbling and leaving large gaps. The largest is roughly 1-1/2 inches. There are also small cracks in the bricks. I should mention we noticed small cracks in the morter after an earthquake several years ago, then the morter just started breaking away from the cracks, leaving gaps.

Do we need to tear down the brick and rebuild, or can we just repair with new morter?
Thanks JE1021

Well it depends upon exactly how much damage you have as to weather you can tuck point the chimney. I suggest you call in a professional brick mason. The reason for this suggestion is the fact that I cannot see the unit from here and there might be interior chimney damage so a special design video camera should be run down the entire length of the chimney so a true condition can be discovered. Many times over the years I have recommended my customers have this service performed before installing new furnaces into the existing flues so as to prevent a more serious problem down the road.

Now if you just tear down the chimney and rebuild then you will find any other problems during the tear down.

NOTE: You mentioned an earthquake in your post and I thought I would mention that your chimney could be having a footer problem from the earth movement. Many times this will not show up right after a quake but later on due to water migration into the void areas around the foundation. If you have a footer or foundation problem it will also cause the mortar to crack and actually dislocate the brick line. Good luck with your project.