When a disaster overwhelms a country, help arrives from many directions at once, and coordinating it is a distinct task from delivering it. The structure explains the visible pace of the first week.
The affected state leads
International assistance is provided at the request of the government of the affected country, which retains authority over what enters and where it goes.
That request defines the operation, because agencies cannot deploy into a sovereign territory simply because they judge help to be needed.
Where a government is itself damaged by the event, issuing that request takes time, and the delay is often mistaken for indifference abroad.
Assessment precedes supply
Sending the wrong goods is worse than sending nothing, because unwanted cargo occupies the same airport apron and trucks that essential supplies need.
Small assessment teams therefore go first to establish what is broken, what local markets can still supply, and where survivors have moved.
Their findings determine the appeal, which is why the first substantial shipments follow rather than precede the initial days of reporting.
Work is divided into sectors
Responding organisations group themselves by function, covering shelter, water and sanitation, health, logistics and other defined areas.
Each grouping has a lead agency responsible for knowing who is doing what and where the gaps are, so effort is not duplicated in accessible places while remote areas go unserved.
The mechanism is essentially an information system, and its value is in preventing twenty organisations from arriving in the same accessible town.
Logistics is the binding constraint
An emergency usually damages the ports, roads and airfields that a response would otherwise use, and capacity is contested from the first hour.
A single runway can handle a limited number of aircraft a day, so arrivals are sequenced and lower-priority flights wait regardless of what they carry.
Much of the early effort goes into restoring these routes, because nothing else scales until they work.
Why donations of goods complicate matters
Unsolicited shipments of clothing and food arrive in quantity after high-profile disasters and have to be sorted, stored and often destroyed.
Agencies consistently ask for money instead, because cash can be spent on local suppliers, which is faster and supports the affected economy.
The preference is logistical rather than bureaucratic: a cash transfer occupies no runway slot and needs no warehouse.