Santorini Earthquake Update 18.2.25 – Epicenters Moving
The epicentres of the Santorini earthquake swarm looks to be moving to the east and the intensity of the earthquakes is increasing. In this Santorini earthquake update I’ll quickly go through what has happened today as of 09:21 GMT, I’ll put some number to the crust movements and then speculate on the cause of these earthquakes.
Links to live earthquake data
Santorini Earthquake Update – Epicentre Movement
An east northeasterly movement of earthquake activity. Until now the majority of quakes have been to the west of Anydros, but most of the quakes over the last few days have moved to the east of the island. Looking at earthquakes since the swarm started and combining it with the quakes of the last few days, it seems the island is starting to be surrounded.
Earthquake Intensity
For the 18th of Feb so far (09:21GMT), we have had a 4.3, 3.8, 5.0, 3.6 and a 4.9. In total, 12 quakes over 3.0 Richter.
This graph shows how the energy being released has doubled over the past couple of days.
Crust Movements
In yesterday’s article and video I detailed how islands in the area had reversed their normal direction of movement. Below is an image showing how far they have moved versus what would be expected.
I’m not sure what it means but it seems that logically, we would expect some stress around Ios and Santorini given they are moving in opposite directions.
GNSS stations south of Santorini are not measuring anything out of the ordinary so I would presume we are not looking at whole plate movement ie the movements are local to the area.
What is the driver of these movements?
What are some possible causes?
Ios
Why has Ios reversed direction and starting to move west instead of it’s normal easterly direction? And is this movement dragging Amorgos west and Sanorini north?
I guess it’s possible the movement of Ios west could drag Amorgos and Santorini north (it is leaving a gap to fill) but that would not explain how a westerly movement of Ios would cause Santorini to start accelerating in an easterly direction. For this reason, I am saying, at the moment, that Ios is not the driver of the earthquakes and the movement of Santorini and Amorgos.
Amorgos
Amorgos island has also reversed direction and started moving west, it’s southerly speed has also increased.
Would this explain Ios’s reversal to the west? Yes.
Would it explain Ios’s movement to the North? No. So I think that rules out Amorgos as the driver of the movements of Santorini and Ios.
Santorini
The island has changed direction and is moving North. Could this drive the changes we are seeing in the direction of the other islands?
The northerly movement of Santorini could force Ios to the west and north which is what we are seeing.
Could the northerly movement of Santorini explain the accelerated southerly movement of Amorgos? No.
Logically, Santorini moving north would also force Amorgos north or at least slow down it’s southerly movement. This is not what we are seeing.
The northerly and easterly movement of Santorini would not logically cause Amorgos to start moving west instead of it’s normal east direction. If anything, it should move Amorgos faster to the east. In short, it does not look like Santorini is the driver of these movement changes either. In my layman’s opinion.
What does the leave?
Anydros is at the centre of the earthquake swarm. Would an uplift or down movement of the crust at Anydros explain the movements we are seeing?
I think that is very difficult to say so the next paragraph will be extreme speculation.
Amorgos & Santorini Converging
We could say Amorgos and Santorini are getting sucked in towards Anydros, like lifting the middle of a table cloth, the edges of the cloth get closer to the middle.
Ios
But we are seeing Ios moving away from Anydros (probably, we do not know for sure because we do not have GNSS data for Anydros. But lets assume Anydros is moving away from Ios) can we explain that?
If we are seeing something pushing the crust apart between Anydros and Ios that would explain the westerly movement of Ios.
Is there evidence for a break in the crust between Anydros and Ios? I think yes.
From the image above we can see the epicentres of most of the quakes can be said to be between Anydros and Ios. So yes, potentially we see a mechanism whereby Ios could move away from Anydros.
Conclusion/Hypothesis
From the analysis above I would speculate that we are seeing uplift, seismic and/or magmatic around Anydros and this is pulling Santorini and Amorgos closer to Anydros (the tablecloth example). I say pulling is a possibility because we are not seeing any evidence in a break in the crust between Amorgos and Santorini, the epicentres are not forming a line from the northwest to southeast.
So uplift at Anydros could explain Amorgos and Santorini being pulled together. And the break in the crust/fault to the west of Anydros (evidenced by the epicentres of the earthquakes) could also cause Ios to move further away from Anydros.
Did the break cause the uplift or vice versa?
Who knows! But if you force me to guess, the fact that we have seen so many earthquakes over such a long period of time leads me to believe, as a layman, that at least some of the energy is coming from magmatic movement. I would say we would expect the strength of an earthquake swarm to decrease over time. Earthquakes are caused by stress in the crust so generally speaking, the more quakes we have, the more stressed is released and the less stress we have left in the crust leading to smaller quakes. We do not appear to be seeing this so I would guess we are seeing magmatic pressure, at least in part, sustaining the energy for the earthquakes we are still seeing.
Does this mean we will see a new volcano?
I have no idea, I would presume the longer the swarm goes on for without reducing in energy released, I would say the chances increase for some sort of magma release, gradual or otherwise. I say this because I imagine there is only so much energy and crushing the crust can deal with, at some point I guess it’s possible it will say enough is enough.
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