Assalamu’alaikum Warahmatullahi Wabarakatuh
Zakat is a bit more specific than usual alms or infaq. Because Allah states that zakat is taken from people with certain criteria, are distributed to people with certain criteria and is also coordinated by a particular agency. Even the amount, time, and established a detailed calculation.
While infaq, usually taken from people with a broad criteria, distributed to the parties to the criteria too broad, not even is quantified.
Then what if Zakat is given to the natural disaster victims?
Back to the condition, which if you meet the criteria for receiving zakat, the law would be allowed. Otherwise, if you given the zakat funds for victims of natural disasters, but you did not meet the requirements and criteria of the zakat recipient, the law should not be.
List of persons entitled to receive zakat was only 8 criteria. If one of the criteria contained in the natural disaster, it may be given to charity. Allah says:
Alms are only for the poor and the needy, and the officials (appointed) over them, and those whose hearts are made to incline (to truth) and the (ransoming of) captives and those in debts and in the way of Allah and the wayfarer; an ordinance from Allah; and Allah is knowing, Wise. (At-Taubah : 60)
See Also: Zakat Mal to Build Mosque
From this verse we can specify that the rules about who is entitled to receive zakat funds are mentioned below:
1. Indigent people
2. The poor
3. Board of Charity
4. The induced heart mu’allaf
6. People who owe
7. For the sake of Allah (Jihad)
8. They were on their traveling
(Ahmad Sarwat, Lc/rumahfiqih.com)