The article says: "The concentric ripples produce one cycle every 10 million years,"
1 year = 31556926 seconds
The period = 10 million years = 3,155,692,600,000,000 sec
frequency(hz)is the reciprocal of the period
so hz would be:
1/3,155,692,600,000,000hz
???
Sincerely
I remain,