We have an outdoor porch that is sitting on a slab (i believe). The one side of it has a pretty substantial crack and I'm wondering the best way to fix. Should i just get some masonry caulk and a backer rod, or should i get some mixture? I believe that they are just concrete bricks that are settling apart and/or water water hydraulicing. At it's largest the crack is about an 1/2 inch in height. The depth seems almost infinite at some points but is at least 2 inches. Here are some pictures for reference.
http://f.cl.ly/items/2y1n1y0I091x3g2V231f/IMG_2861.jpg
http://f.cl.ly/items/393J373P3v302D2F2a15/IMG_2864.jpg
16 inch ruler http://f.cl.ly/items/2R331q193a2y0t0Y0M40/IMG_2865.jpg
Advice, pertinent articles, or best googling terms greatly appreciated.