GEOLOGY

Detailed explanation-1: -Seismic Monitors An increase in earthquakes can be a sign of an impending eruption. Researchers use seismic monitors to track the many small tremors that occur around a volcano.

Detailed explanation-2: -The USGS Volcano Hazards Program (VHP) monitors and studies active and potentially active volcanoes, assesses their hazards, and conducts research on how volcanoes work in order for the USGS to issue “timely warnings” of potential volcanic hazards to emergency-management professionals and the public.

Detailed explanation-3: -The COSPEC (correlation spectrometer) A correlation spectrometer (COSPEC) is designed to measure the amount of sulfur dioxide in a passing air mass (or volcanic plume). The spectrometer compares the amount of solar ultraviolet light absorbed by sulfur dioxide in the plume to an internal standard.

Detailed explanation-4: -Probably the most common type of monitoring is by seismicity. Even one seismometer can tell if there is an increase of seismic activity on a usually seismically-quiet volcano.