for each loop read access violation

I've been writing an engine and ran into a problem, I'm getting a read access violation in my code. I have no idea why, but it happens when I add this->chunks.push_back(chunk); into this block of code,

void c_world::generate_world()
{   
    this->chunks.resize(MAX_CHUNKS);

    for (auto chunk : this->chunks)
    {
        chunk.setup_landscape();
    }
}   

so it becomes...

void c_world::generate_world()
{   
    this->chunks.resize(MAX_CHUNKS);

    for (auto chunk : this->chunks)
    {
        chunk.setup_landscape();
        this->chunks.push_back(chunk);
    }
}   

this->chunks is an std::vector<c_chunk> (c_chunk) being a custom class. Thank you!

All helps appreciated.