Dragon Head 1

Teru and his high school class are returning from a field trip when a catastrophic something derails their train, burying them in a tunnel and killing nearly everyone aboard. Among the hellish heap of mangled bodies Teru discovers two survivors, but their nightmare has only just begun. Trapped in unending shadow with sudden, violent earthquakes shaking their sanity, the three must find a way to escape to the outside world and make it back home—if home still exists…

Volume 1 of the Dragon Head manga series by Minetaro Mochizuki.