I think you will find they are from Vietnam.
I think also you will find they are not people but web bots
And the way to fix it is to put some sort of interaction onto the posting window.
I use captcha but I get complaint from members who might have to try 2 or 3 times to prove they are a real human.
Also there is a better than average chance they are using a zombie computer belonging to an idiot in the USA who has joined this sit and does not have proper cyber security on his computer.
As such zone blocking would be pointless.
Google URL spoofing and you will understand why zone blocking does not work against these types of spammers.
In fact it looks rather like they have hacked into the members registry.
Depending upon the softwear the server is using they might be able to use profanity filtering to block the postings by adding a couple of words used in all the posts to the list of swear word triggers.
I use that with success for a while till the spammers got smart and translated their spam into English.
If you look closely at the members names you will notice it changes every so often so the faster the moderators delete the spamming users the faster they change ID.
The rest of the profiles look ligit which is why I think they have hacked the members registry.