The Icelandic Meteorological Office (IMO) lowered the alert level of the volcano back to yellow, as relatively few quakes were detected in the monitoring area and decreased again to normal values. It happened after almost 2 days when the observatory raised the alert level to orange due to elevated seismic activity.
The IMO’s earthquake hazards coordinator Kristín Jónsdóttir explained: „When the seismicity increased we needed to react as it could have been a typical precursor of a volcanic eruption. We need to react to any relevant changes in the volcano activity. In this case it was likely that an eruption would have been triggered by the flood, and sometimes the time between the two events is not that long so we needed to be ready. This scenario, that a flood will trigger an eruption is becoming less likely as time passes.“
The ice sheet has continued to drop and reached already about 80 m in total subsidence.
The detected precursor is very short which is why an explosion may come as a surprise and need to be monitored closely.
Source: Icelandic Meteorological Office volcano activity update 8 December 2021