Cerro Negro de Mayasquer volcano (Colombia): continuing earthquakes, appearance of seismic tremor

The seismic crisis that began last year continues at high intensity. During the ongoing swarm more than 206,000 earthquakes have been detected in an area 4 km south of the Chiles-Cerro Negro complex since 29 Sep alone. Daily numbers of quakes have ranged between 3700-5400 earthquakes.
While most quakes have been very small, a few were strong enough to be felt by local inhabitants.
One possible cause of the earthquake swarm is a magma intrusion at depth, which could be a precursor to new activity of the volcano. This hypothesis is becoming more likely since weak episodes of seismic tremor have started to appear on seismic recordings of stations near the volcano. Tremor are long-lasting regular ground vibrations typical for fluid movements at depth. These could be magma, gasses and/or hydrothermal fluids (water). Which of them is responsible cannot be said at the moment.