'std::bad_alloc' or even wrong vector size when using iterator on vector

I got terminate called after throwing an instance of 'std::bad_alloc' when trying to push an additional string to a middle of a vector. I used g++ 4.8.2.

I even got output with wrong vector sizes size of str_vector 0: 1, size of str_vector 1: 1 when using g++ 5.2 on coliru.

The program works correctly when I use index (e.g., str_vector[0]) to access vectors or use std::list.

Does this mean there is some restriction on the use of iterator? I assume that there should not any difference when I use index or iterator to access vectors.

#include <iostream>
#include <string>
#include <vector>

using std::vector;
using std::string;

int main() {
        vector<vector<string>> str_vector;

        str_vector.emplace_back();
        vector<vector<string>>::iterator it0 = std::prev(str_vector.end());
        it0->push_back("a");

        str_vector.emplace_back();
        vector<vector<string>>::iterator it1 = std::prev(str_vector.end());
        it1->push_back("a");

        it0->push_back("a"); // bad alloc here

        std::cerr << "size of str_vector 0: " << it0->size() << std::endl;
        std::cerr << "size of str_vector 1: " << it1->size() << std::endl;

        return 0;
}