Look at this seismogram of Fredericksburg Observatory next to US Army Garrison Fort in Virginia. It is BLACK!
Whenever I see almost black seismogram, I check the nearest location of military bases or quarries & mines (=Reptilian/military Secret Underground Bases)
Right now, Galactic Federation of Light has been cleaning up those secret underground bases inhabited by Reptilians & hybrids. Those cleaning up operation can make some seismo-activities (=ground shaking).