What is the enumerated power within the US Constitution under which FEMA is sanctioned?

 Emergency powers ... tend to kindle emergencies

The Constitution of the United States represents the best solution to one of mankind’s greatest political problems. How does a small group of states combine into a strong union without the states losing their individual powers and surrendering their control over local affairs? 

The delegates who convened in Philadelphia in 1787 answered this question with a document that called for a federal plan of government, a system of separation of powers with checks and balances, and a procedure for orderly change to meet the needs of future generations.

The Constitution confirms the proposition that original power resides in the people. All powers not reserved by the people in state constitutional limitations remained in the state governments, NOT the federal government.

The United States Constitution does not contemplate emergencies.

The Constitution does however provide authority for government to anticipate and then respond to emergencies.

Article IV, Section 4 of the Constitution obligates the federal government to guarantee a “Republican Form of Government” to each state, to protect the states against invasion, and to protect them against “domestic violence,” but only after a request from the governor or legislature.

The national government may govern only through the powers enumerated in the Constitution. The states have the “police powers” to protect the health, safety, and welfare of their citizens and these are reserved for them by the Constitution. The breadth of the police powers provides states with the dominant authorities to respond to emergencies, so long as they do not violate the constitutional rights of their citizens.

After looking far and wide I have found lots of studies and reports about this or that law but the constitution seems to be avoided when the subject of FEMA come ups, hhhhmmmmmm.

...and I still cannot find any authorization for it anywhere in it.