nginx - host blog.domain.com from /myapp/public/blog and prevent access from my app.com/blog/*?

Having a server setup like below. I would like to restrict anyone from accessing http://myapp.com/blog/index.html which would route to /public/blog/index.html. Is this possible or should I really store the blog folder outside public? ( Which I don't want )

server {
  listen 80;
  server_name
  myapp.*


  root /srv/myapp/current/public;

}

server {
  listen 80;
  server_name
  blog.myapp.*

  root /srv/myapp/current/public/blog;


}