Simulating earthquake on terrain

public void SimulateEarthQuake()
{
    for (int x = 0; x < _terrain.Width; x++)
    {
        for (int y = 0; y < _terrain.Height; y++)
        {
            _terrain.Heights[x, y] = _terrain.Heights[x, y] + _random.Next(-3, 4);
        }
    }
}