It's all a big conspiracy to hide the fact that quakes are getting worse and that we're all gonna die and the powers that be don't want to panic us all by telling us thus maintaining their stranglehold of power of the population for all the usual nefarious reasons.

But seriously, in this case it was probably because most of the instruments detecting the quake were within the strong shaking zone and were saturated. In other words, the volume was too high and it pegged the needles.

Brian