In 1964, the world's 2nd largest earthquake hit Anchorage, Alaska causing catastrophic damage to the city as well as the land sitting on it. Before the quake, this area was flat residential area. Now it's a small forest riddled with small hills and muddy ponds.
Before taking my metal detector out, I contacted the proper park officials who told me "Technically no but it's not against the law. So as long as you don't take anything from the park or destroy anything, you should be ok.". All of my holes were small and properly reburied out of respect for the park and it's natural habitat, as it should always be.