Tunnels have been discovered under the building that collapsed.
Yeah, I saw those reports...and that’s bad reporting perhaps driven by a translation problem. Those are ‘debris tunnels’ or ‘voids’ that were created when the building fell. Probably not the kind of tunnel you and most other English-speakers think about when you hear the word ‘tunnel.’
Historically, when rescuers find people alive alive, it’s in these ‘debris voids’ that the people are found. So, when rescuers begin to find voids, hope increases at least temporarily.