Servicio Geológico Colombiano (SGC) reported that a seismic swarm below Cerro Negro de Mayasquer and Chiles volcanoes began at 0100 on 3 December.
The events were classified as volcano-tectonic, with epicenters located up to 6 km from the summit of Chiles volcano, at depths of less than 8 km (4.7 km a.s.l.).
The maximum local magnitude was 2.3.
From the beginning of the swarm until the time of the report posting (1640) there were about 5,400 recorded events, making the swarm the largest since 2015.
The report also noted that seismicity had gradually been increasing in recent weeks.
The Alert Level remained at Yellow (level 2 of 4).
Source: Servicio Geológico Colombiano (SGC)