I thought it’s predicted to be able to see the actual waves in an earthquake 10.0 and larger.
In 1972, we had an earthquake centered in Sylmar, California. At the time I lived about 20 miles away in La Crescenta. The magnitude was 6.5.
It took place around 7:00am. My friend had opened up the local Mobil Service station and was there alone. He was out front where he could look up the street, and he watched the waves come down toward him.
This unnerved him so badly, that he jumped in his car and drove home leaving the business wide open.
For this reason, I know that those waves can be seen at much much lower magnitudes than 10.0.
My father was in the basement of the Los Angeles County Hospital when an earthquake came through decades ago. He stated that he saw a wave coming down the hall toward him. I don’t know which earthquake it was, or what the magnitude was.
The first earthquake that I ever felt was in Whittier, CA. I not only felt it, but heard it. It sounded like a train coming down the road.