High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at Redoubt Volcano, Alaska

A combination of satellite and airborne high-resolution visible and thermal infrared (TIR) image data detected and measured changes at Redoubt Volcano during the 2008–2009 unrest and eruption. The TIR sensors detected persistent elevated temperatures at summit ice-melt holes as seismicity and gas emissions increased in late 2008 to March 2009. A phreatic explosion on 15 March was followed by more than 19 magmatic explosive events from 23 March to 4 April that produced high-altitude ash clouds and large lahars. Two (or three) lava domes extruded and were destroyed between 23 March and 4 April. After 4 April, the eruption extruded a large lava dome that continued to grow until at least early July 2009. ► High-resolution satellite and FLIR TIR detected thermal precursors before the eruption. ► ASTER and FLIR TIR detected the highest temperatures during increased dome extrusion. ► FLIR TIR textural differences define a rubbly, upper lobe over the dome's blocky base. ► Early detection of thermal precursors requires frequent high-resolution satellite TIR.