Perhaps we simply got better at detection?
> Modern recording equipment has been in use since about 1900.
What is the difference in sensitivity between a seismometer made in ~1900 vs 2023?
> Modern recording equipment has been in use since about 1900.
What is the difference in sensitivity between a seismometer made in ~1900 vs 2023?
Just off the top of my head, I'm quite sure there were more than 3 earthquakes with magnitude between 5.0 and 6.0 for the 80 year span between 1900 and 1980.
Also, there's a notable discontinuity of exactly magnitude 7.0 earthquakes starting at the year 2000 that doesn't look like raw data.
More sensors don’t really add more detections, but are useful for pinpointing an origin.
Here's a quick rundown: https://slcc.pressbooks.pub/physicalgeography/chapter/4-3/