Rocking & Rolling in 1954
If you ever thought you saw the ground rolling in an earthquake, it was not your imagination.
Memories are life-sustaining. In my line of work, they can also be data, I so appreciate the memories many of you sent about the 1954 earthquake (see “What Your 1954 Earthquake Memories Told Us,” Senior News, November 2025).
One of the things many of you recalled that stuck in my mind and made me want to poke further was that nearly half of the 40 of you who remember the 1954 Fickle Hill earthquake recalled seeing the ground roll “like waves on the ocean.”
This wasn’t the first time people have told me about seeing the ground undulate. When I was collecting data from the 1992 Cape Mendocino earthquakes, several people described the same phenomenon. Early earthquake intensity scales included it as a measure of the strongest shaking, but by the time I was introduced to seismology in the late 1960s, most of my professors discounted it as an illusion.
I didn’t seriously question that until I read account after account of the ground rolling. A seismologist friend saw that ripple during the 1989 Loma Prieta earthquake. Another colleague’s father-in-law had described it during a 1933 earthquake. My sister remembers seeing it twice in the 1950s. Almost everywhere I poked in newspaper descriptions of large daytime earthquakes, there was a ground-roll story.
My request for recollections of the 1954 earthquake said nothing about the rolling phenomenon — just tell me what you remember. Responses came in one at a time — email, telephone and sometimes one-on-one interviews. Most of my respondents hadn’t thought about their experience for 70 years. Only a few things consistently stood out — seeing chimneys fall, the ground roll and their parents being frightened.
I am convinced that what everyone saw is real. Now to figure out what it was you were looking at. I convinced several seismology colleagues to investigate further. First, we gave it a name: visible ground roll (VGR). Seismograms record the motion of the ground. Could VGR be in the visible range? Two earthquakes on our list had strong motion instruments in the same area as the reports came from, and both clearly showed ground displacements on the order of several inches, with wave periods of about 10 seconds. They were in the surface wave part of the seismic wave train, the longer period waves that come after the sharp shaking.
More sleuthing is needed to nail down the cause, and your accounts help. A few days ago, I got an email from Yoshi Uemura, someone I met 20 years ago. A keen observer, he gave the most remarkable description: “I would estimate the wave size to be around four feet, peak to trough. It did look like ocean waves coming toward us at a very, very fast speed. If I had to estimate speed, I’d say about 200 mph — about the speed of an airplane flying by at rooftop level.”
Your earthquake memories are valuable to help bring VGR back into seismological respectability. If you have more to report, email kamome@humboldt.edu or leave a message at 707-826-6019.
Lori Dengler is Humboldt’s go-to earthquake and tsunami expert, an emeritus professor of geology at Cal Poly Humboldt and the regular “Not My Fault” columnist in the Times-Standard.
