Icelandic Met Office released interesting graphs of the activity in Katla volcano during the 28th and 29th of July-2017. It gives clues to what might happen just before an eruption in Katla volcano.
Harmonic tremor pulses
On the 28th of July small and short harmonic tremor pulses appeared on SIL stations around Katla volcano. When 29th of July did come the harmonic tremor intensified considerably from what it had been the day before. The harmonic tremor pluses on 28th of July is close to impossible to see on the harmonic tremor plot on Icelandic Met Office website.
Harmonic tremor pluses as they appear on Icelandic Met Office tremor software on 28th of July-2017. Each frequency has it’s own line. Time is horizontal and intensity is vertical. Copyright of this image belongs to Icelandic Met Office.
This data suggests that before an eruption happens some type of boiling or increase in hydrothermal vents takes place in Katla volcano. This is also connected to the glacier flood that followed into Múlakvísl glacier river.
Glacier flood and harmonic tremor
Blue: Water level. Red: Conductivity. Green: Tremor activity. Values are at 10 minute central value. This data is from the SIL station at Lágu Hvolar. Copyright of this image belongs to Icelandic Met Office.
There seems to be some connection between the harmonic tremor change and the changes in the glacier flood. That suggest in my view that a minor eruption took place in Katla volcano during 28th and 29th of July. How long the eruption did last is a good question. Harmonic tremor data suggests it was only for few hours before it ended. New cracks have been seen around Cauldron 10 in Mýrdalsjökull glacier according to reports. Locations of cauldrons in Mýrdalsjökull glacier can be found here on University of Iceland Earth Science map.
That would be the end of the story in most normal years. Minor eruption and then nothing more. That does not seem to be the case this time around. Small pulses of harmonic tremor have been taking place during the week (Week 31) and that seems to be ongoing process. Most of the tremor pulses are hard to see on the SIL stations and most don’t even appear on more then one or two SIL stations. At the moment Katla volcano is quiet and that might go on for a considerable amount of time due to this minor eruption (my view) and connected glacier flood.
Please remember to support my work. Currently I am really broke and this month is going to be difficult like earlier months of the year 2017. Thanks for the support. 🙂
This financial situation is slowly getting better and is going to be fully or mostly resolved by July-2018 I hope.