The eruption was preceded by a significant swarm of tremors on September 11.
Intense earthquakes are not a guaranteed warning sign of imminent eruptions, but cannot be discounted either.
According to the US Geological Survey (USGS), there are many volcanic processes that can trigger a wide range of seismic activity.
The USGS said: “Most volcano-related earthquakes are too small to feel, generally quite shallow (usually within 10km of the surface), and can occur in swarms consisting of dozens to hundreds of events.
“Most swarms usually don’t lead to eruptions, but most eruptions are preceded by swarms.”