What is the most effective immediate response to a volcano eruption other than evacuation, search and rescue?

In this case one may argue that the most effective response would be to channel the lava away from any cities or economcially valuable land. This is where they create (usually by digging or TNT) large troughs in which redirect the lava. They did this in the 1983 Mt Etna (Sicily) eruption, where the Italian army and local volunteers dug (by hand and using machinery) a diversion canal (6m x 4.5m) and blew up various sections of the solidified lava to divert it away from the local towns of Regalna and Bel Passo. This prevented potetially £30mn of economic damage. However, we must understand that with volcanic eruptions, one size doesn't always fit all. In this case, we must remember that it was a lava eruption. If it were ash and tephra falls, lahars, 'gas leaks' or another type of eruption, this method would be inaffective. Moreover, the viscous andesitic lava type enabled this to work - if it were the runny basaltic lava, they may not be able to react in time. Finally, it fundamentally depends on the financial ability of the country - LEDC may not be able to afford it. Hence, even though it is arguable the best method of management, we must understand its limitations when assessing it.