The people of Tonga are safe within their homes where no ash exists. It will be a difficult rescue as helicopters will raise too much ash and the people can inhale it. Food drops are necessary as the USA did in Afghanistan in 2001. The ash is also in the water. There may be water pipes the still carry potable water to homes and buildings.
The ocean water surrounding the island need to be tested for Ph levels at the periphery to know the content of the water to send in boats. Slow approach is best to prevent mixing. The ash in time will fall to the bottom of the water column.
There is few good ways to clear the ash. Construction equipment to lift the ash and dump truck to carry it. The first storm that comes with create thick cement like liquid that can be moved with graders. Much will wash into drainage systems that will cause a problem.
There is a lot of it. This is not the first time villages have cleared ash from any habitat areas. My greatest sympathies to Tonga for any losses they have sustained.
