As someone who have grown through the terror of earthquake and having lost people that I knew in that big one that happened back in 1995 in my hometown, I found the first episode very immersive and very well made. Terrifying even and I was holding my breath from what was happening.
So imagine how devastating it was to keep watching this after being so wowed by the first episode, only to see it going downhill so much faster than the sinking Japan...
Honestly I don't know why this turned out like this. What is happening and how, is beyond stupid and comprehension, you just can't get your mind around on the decisions, and the events that occur during the family trip.
Also while the first episode felt like it was made from someone who have experienced the terror of a big scale earthquake, what is happening after this just makes you wonder if the writer had even a little bit of understanding of what is happening in the aftermath of that said earthquake, how the people feel, how they react, how the authorities react and work, and the general feeling of the situation that SHOULD be familiar for the earthquake shaken Japan's population, is just not there.
Nope, collapsed buildings, rivers of blood, dead bodies on the streets, but nobody seems to realize the severity of the situation or the situation at all, like they are all high or something...
It really feels like some short of trekking trip from a point on, a trip that insane and terrible things happen, that not only make no sense but are borderline impossible to believe what happened. Like the writers where like "if Japan can sink, I can do this crazy thing too". You are more likely to believe that Naruto existed and could turn into a nine tail fox than what is happening in this anime here.
Anyway. Watch at your own risk.