“7.6 massive? 9.0 or greater is massive.”
Strongest earthquake recorded in California was the 1906 San Fransisco quake at 7.8. So yeah, 7.6 is pretty darn strong.
I was in a 7.5 in Mexico City in 1957. We were walking home from a party at 1 am. and I started go stagger. Me, “Gee, I only had one drink.” Friend from San Jose, CA, “No, it’s an earthquake.” We saw the wires overhead swaying back and forth and ran to the middle of the next street intersection to be away from the wires and the 3 story buildings. The ground was quaking around like a New York subway train and we were holding on to each other to keep from falling down. It was strangely silent except for the wires clacking against each other. The next day I walked around town taking photos. A building under construction had pancaked about 5 stories. A 20 story office building had many broken windows and cladding had broken off the surface, A friend while walking near the 40 story “little Empire State Building” said whores had been running out of the building screaming, crying, and praying on their knees. I think fewer than 200 were killed. Over the weeks I felt a number of aftershocks. This was NOT like the “massive” Mexico City quake in the 1980s that killed 10,000 people.
1906 San Francisco quake of 7.8 was probably much stronger as the city is on stone bedrock or reclaimed marsh land. Since Mexico City is in a dried lake bed it quakes, not shakes. Also I think the number increase is geometric, not linear. A lot of the SF damage was caused by fire in wooden buildings. The apartment where I lived faced the Social Security building on the Avenida Reforma. It was built in three blocs, and across the street one segment had a 3 foot wide split away from the center section. When I got home they said the living room chandelier had swung from side to side hitting the ceiling on both sides. All the 3 foot tall plant pots had fallen over dumping soil. The guy living upstairs fell out of his bed. So, certaining noticeable, but not massive at 7.5 on soft ground.
I was also in the Washington Metropolitan Area during the 2011 Mineral, VA 5.6 quake. I was sitting on the edge of my bed when the wall opposite started to quiver and I felt shaking for 15 seconds. I thought maybe it was a heavy truck, but shortly the earthquake was announced as 5.6 in Mineral. I kept a bowl of water near where I sat for over a week and several times saw the water ripple. I would turn on the TV and soon an announcement of a small 2.? aftershock would be announced. I had a cracked chimney, and a neighbor’s chimney collapsed. DC had $11 million in damage, much of it to the National Cathedral. I think around DC the level was 4.?.