Assess disasters and geohazards by EO includes alert & early warning, emergency mapping, and risk & recovery mapping. It relates to observations, controlling, assessments that are linked to natural and human made risks. Typical disasters that can be assessed by EO are in particular floods, droughts, forest fires, landslides, tsunamis, earthquakes, cyclonic storms and volcanic eruptions. Since with EO it is possible to quickly analyse the risk or damage it is used to effectively plan emergency response actions.
There are several measures to minimize or prevent the damage caused by disasters. Some of them have to be carried out in anticipation of a disaster, others after the occurrence of an event. The different phases that are needed to reduce or avoid the impact and to assure rapid response and recovery are described in the disaster management cycle. Depending on the cycle phase, EO has to meet different requirements. The Mitigation and Preparedness phase are passed through in anticipation of a disaster event. Thus, requirements to EO products may focus on high completeness of mapping or high accuracy of mapping. In contrast, Response and Recovery phase include rapid mapping, thus EO capabilities must meet near real-time delivery requirements.
As well, the nature of the disaster determines which EO products are used. Optical sensors are used throughout the different types; however, landslides are mostly assessed by radar sensors and thermal sensors are additionally used for forest fires.