[AnotherGoodName]

In fact i hypothesise they've inverted cause and effect.

Tectonic movements absolutely have the energy to move the earths magnetic field and the magnetic field blocks cosmic radiation. Something that moves the magnetic field would allow more cosmic radiation

There's only a handful of detectors outside of earths magnetic field. Orbiting satellites are even within its field of influence. Comparing this data to the measure of cosmic radiation from a deep space probe would be interesting to rule out that it's the earth movement increasing detected radiation and not the reverse

They may have simply discovered that tectonic movement changes how much cosmic radiation reaches our detectors.

[Enginerrrd]

From the article, that is in fact their explanation. There's just possibly some other data that could point the other way, but it's not heavily emphasized.

There have been other studies that showed weird correlations to ionospheric activity and earthquakes, but only ever in retrospect.

[pomian]

What you wrote, is a good place to start future observations. There is a lot of unexplored dynamics to investigate, in the earth. Roiling hot fluid and gaseous systems in flux, which are magnetic - due to iron (and other minerals), is a fluid dynamics dream subject. But, how to finance? In today's research systems driven by funding to support specific answers, instead of expanding knowledge just to see what we learn.

Ps. An attempt at modeling the inner Earth's systems and flows might be more useful for earthquake prediction.

[idlewords]

I hypothesize you didn't read the paper, which you've instead derived from first principles.