The use of archives for the long term monitoring of active volcanoes

Changes in the activity modes of active volcanoes can occur as very short term run-ups in seconds to days before eruptions, or may manifest as systematic changes occurring over a years to decades or longer. Understanding how timescales relate to underlying physical processes is key. In this context, it is important to understand the limitations and potential utility of new large remote sensing data archives. These archives have particular relevance to operational detection of eruption precursors at the longer end of the timescale spectrum.