Seismic activity under volcanos in Chile has recently begun to increase causing Chile to raise its volcanic alert level to “yellow”. The area of concern is located around Cerro Hudson, in the southern Andes.
Seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. The frequency of volcanic quakes in Chile increased from 10 during August and September to 70 in November. During November, phases of tremor and so-called hybrid earthquakes, which represent magma movements have also been occurring. Usually safety alerts will change due to an acute change but this time the alert came because of these accumulated events. Chile’s ONEMI (Oficina Nacional de Emergencias) and SERNGEOMIN (Chilean Geological Survey) have set up a 3.5 kilometer exclusion zone around the volcano; a response that is informed by the last eruption of Hudson in 2011. The 2011 eruption, though a smaller eruption, opened three new vents on the volcano, indicating why this recent seismic activity needs to be closely monitored.