I’ve noticed after many earthquakes in Croatia (and maybe other countries), the magnitude changes…how come ?
why is it different sometimes between EMSC and other places ?
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It is not rare that, in the aftermath of an earthquake, seismological agencies report a first estimate of the earthquake magnitude, but subsequently modify it -downgrading or upgrading it.
Calculating an accurate preliminary magnitude is difficult because the earthquake itself is a complex process. Besides, several different techniques exist to calculate the earthquake magnitude. Some techniques are easier to apply and can return an approximate magnitude value within a few seconds from the earthquake onset. Other methods, on the contrary, are more robust, but require large data sets, extensive analysis, hence longer computing time.
When an earthquake strikes, it is important both for the seismological agencies and the citizens to have rapid, preliminary information about the earthquake size. With more data coming in, and more time dedicated to the analysis, seismologists can, in a longer time range, return a refined and more accurate value of the earthquake magnitude.
So no worries if it changes, it’s part of the process 
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I think this is not a problem of precision. It is mostly caused by algorithms or data amount. If an algorithm contains expert opinion and approval, it may come late. Maybe AI resolves these situations. Because AI learns from and gathers real world data and bias like human, so produces results similar to real life. But AI needs much more data than a human!
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That’s also true, AI could help out with the magnitude estimate !
We should just be careful because human create these algorithms so they may be biased in their own way.
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Actually AI could do even more for seismology !
Here’s a paper by Pengcheng Jiaoa and Amir H.Alavi about AI in seismology Artificial intelligence in seismology: Advent, performance and future trends - ScienceDirect
You can also check this video : Basic Geophysics: Artificial Intelligence in Seismology - YouTube
Dr Andreas Barth explains how machine learning can be used to determine seismic wave arrivals.
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