Home Improvement

The big gap looks like the mortar has just deteriorated to the point that it's fallen out. It's not ideal but not necessarily an emergency yet either. Most likely the ground under the foundation has settled a bit. How urgent it is depends partly on whether the crack continues to expand. I would check it every week or two for a few months and see if it gets any wider. You can use a deck of of cards and keep track of how many you can squeeze into the crack. That will tell you if it's expanding.

I would also suggest making sure you don't have rain water collecting anywhere next to the house. If you have downspouts, make they're they're diverted away from the house as much as possible.