A swarm of earthquakes started to occur beneath the Chiles-Cerro Negro volcanic complex on 9 March at 11:00 local time, the Red de Sísmica Nacional (RENSIG) and Observatorio Vulcanológico de Pasto (OVP-Colombia) reported.
A volcano-tectonic earthquake with magnitude M 3.4 was detected and even felt by local residents. The swarm itself has been accompanied by 4500 small, mostly long-period/low-frequency earthquakes with a rate of about 200 events per hour, so far. This could suggest elevated fluid movements of gas, water and possibly magma under the surface.
Seismic swarms beneath the volcanic complex appear regularly as seismic activity is mainly distributed beneath the E-SE area, near the Potrerillos region. It is worth mentioning that the largest magnitude over the past year was recorded with magnitude of M 5.6 on 25 July last year.
Source: Instituto Geofísico volcano activity update 13 March 2023
