Satellite sensors acquire information at different wavelengths of the electromagnetic spectrum (multispectral) and can therefore detect features which cannot be identified in the visible part of the spectrum. Satellite images also cover large areas which can be used to monitor large regions, or regions which cannot be observed from Earth (e.g. hostile terrain), or to get an overview of a region which cannot be observed from the ground. Moreover, less logistical effort is required, and satellite images can be an alternative to field survey.

All the above mentioned points play a key role in the following exercise, which also aims to extract information for hazard assessment. We will see how satellite data can be used for:

• Analysing and inspecting a volcano
• Monitoring changes of a volcano over time
• Detecting lava in infrared bands
• Assessing possible threats to humans by creating a hazard map