You ask me about Europe.

There are always 4 interconnected places in an equilateral earthquake triangle.

[link to www.pollsb.com]

The outside points are equidistant to each other and there is also an invisible inner point (inside the triangle, also equidistant to the outer points but with different distance.
(always lower distance inside than outside)

If you have only 2 earthquake points in a map, with no other equidistant points, you will need to wait until another equidistant earthquake hit or try to figure out but you will end with 16 to 32 possible future points.

If you have 3 equidistant earthquake points in a map you can predict the other one.
But you will end with 8 points of possible hit.
That's why I wrote "chances".