Santorini Earthquake Update 19.2.25 – The Missing GNSS Station
For today’s Santorini earthquake update (09:53GMT) we can say, over the past 24 hours, earthquake activity is down markedly. Let’s look at the intensity data and see how it compares to the movement of the islands.
Links to sites giving live raw data
Intensity – Santorini Earthquake Update
Looking at energy released and seismographs
Cumulative Energy Release
Versus the previous 24 hours, the cumulative energy released by earthquakes in Greece as a whole is down by around 95%. On the 18th of Feb the cumulative energy released in the previous 24 hours was 2000MWh, the update this morning (19th) is showing around 90MWh released. A big difference. Looking at the energy release trend, today brings us back in line with the gradual downward trend we have been seeing over the previous 7 days.
Anydros – Seismograph
Anydros island has been the closest seismic measuring station to the Santorini earthquake storm. Today’s seismograph data is showing a big reduction in activity versus the 17th of Feb.
Activity Location
Yesterday we were seeing a movement of the earthquake epicentres to the east of Anydros. Today the epicentres are south west of Anydros and in a general line that points towards Santorini.
There is some talk of there being a very narrow dyke (small gap in the crust) leading from Santorini to Anydros and in this dyke magma could be present. If this is correct, the line of epicenters of the past 24 hours might indicate magma movement in this hypothetical dyke.
Seismic Data – Summary
The cumulative data matches what we are seeing at Anydros, frequency of seismic activity in general is down and so is the intensity of the earthquakes that are occurring.
Island Movement
Are we seeing any changes in the general movement of the islands/GNSS stations over the past 24 hours?
Ios
Ios’s northerly and westerly movements seems to be slowing
Santorini
Santorini’s movement North looks to be slowing and perhaps also its movement east. It’s downward movement looks be accelerating.
Amorgos
Amorgos south west movement looks consistent with the past 30 days. Uplift rate may be increasing but we need more data points to confirm any new trend.
Summary
Again, the evidence appears to be showing us the activity is dying down due to the slowing movement of the islands.
One mystery we are seeing is the dropping of stations in Santorini. And this seems to be a consistent trend downward. If this downward movement has a seismic cause, where are the earthquakes to go with it?
If the downward movement is due to magma (or magma pressure) moving elsewhere, could this magma be travelling north east and causing the quakes we are seeing in the hypothetical dyke heading towards Anydros from Santorini? I guess it’s possible and it would be consistent with the magma dyke theory.
Big Picture Summary – Santorini Earthquake Update 19.2.25
At the moment, the data is pointing to a calming down of activity in general, be it from an earthquake intensity point of view and from a movement point of view
Addendum – The Missing Station
The missing station, which I highlight constantly, is the station giving GNSS data for Anydros. Is there one there? If not, why not? And if there is, where is the data?
GNSS data from Anydros would give a much clearer picture of what is happening in the area. In the previous update I said that I believe what we are seeing is localised. And Anydros island is in the centre of this area, data from Anydros would give so much more meaning to the other data we are seeing, it would let us link up the data from the surrounding stations and potentially give us a much higher resolution picture of what is actually happening.
For example
Movement data from Anydros could tell us if the uplift in Amorgos is localised to Amorgos or is the uplift being seen in Anydros. And if there is uplift in Anydros knowing if it is more or less than what we see in Amorgos would give us a better understanding of how widespread the uplift is.
We could also link vertical data from Anydros to Santorini to see if there is a connection between the movements of the two islands.
East west movement data from Anydros could give us a better idea of the location of the potential fault between the earthquake area and Ios. If Anydros is moving west at the same speed as Ios perhaps we could say the fault is east of Anydros. And so on.
We could be getting a much richer picture of the earthquake area with data from Anydros. It’s a shame this station data is missing.
