Here's what Mt. Etna looks like before it erupts
Channel: AGU
Date: 2018-11-28

Italian seismologists have developed a new volcanic early warning system that monitors volcanic noises and automatically alerts officials if an eruption is imminent. The Italian government used the new system to activate an emergency plan about one hour prior to an eruption of Mount Etna in Sicily for the first time in late 2015.

This video shows thermal imagery of an explosive eruption that occurred at Mount Etna between 11:00 p.m. of December 3rd, 2015, and midnight of December 4th. The thermal images are synchronized with seismic tremors (upper panel) and infrasound (lower panel) generated by the volcano that the new system uses to deliver automated warnings to local officials. 

The colored bands in the lower panel indicate when the pre-warning (orange) and the warning (red) have been automatically delivered. The pre-warning phase precedes the eruptive phase by almost one hour. The sound in the video reproduces the recorded infrasound, which is below the level of human hearing. The explosions from inside the crater generated the crackling sounds, which increase in rate as the eruption approaches. 

Read more about the new early warning system here: https://blogs.agu.org/geospace/2018/11/28/new-automated-volcano-warning-system-forecasts-imminent-eruptions/ 

Video Credit: M. Ripepe et al. 2018, Journal of Geophysical Research: Solid Earth/AGU.