In August 1989, the San Francisco Bay area experience a mild earthquake in the middle of the night. It woke me up.
The next day the San Jose Mercury News reported on the quake and included a table of all magnitute 5 and larger earthquakes in the Bay Area since 1906. I took these data and plotted >5M earthquakes per decade.
The plot showed an exponential increase in the >5M earthquakes during the last few decades. My observation at the time was that the '80s weren't over yet. Two months later we had Loma Preita.
Magnitude matters. If I had plotted all earthquakes >2.5M the signal that pointed to Loma Prieta would have been lost in the noise of minor quakes. Magnitude 5 quakes or larger are telling us something. Smaller quakes are noise.
5:55:22 AM 
|
