Claire Rubin shared the latest report from National Institute of Building Sciences, see Natural Hazard Mitigation Saves: 2017 Interim Report. The return on investment documented in the report betters the older formula that I've seen quoted for many years of 1 to 4.
This being that for every dollar invested in mitigation you save six dollars in prevented damages.
Another technique to save on natural hazard damages is to not build where a hazard exists! But, silly me, why would we do that?