EQF;

What evidence do you have that these signals have anything to do with earthquakes?

That should be the first thing you do because without it, you're just speculating.

The second step would be to show that there is a statistically significant correlation between the peaks and earthquakes, allowing for a reasonable lag time.
After all, there are only so many longitudes and so many quake locations. They're bound to correspond once in a while by chance, particularly if you wait long enough.

Roger