The geologist’s warning that a strong earthquake would strike the Bay Area during the 1989 World Series was published in the Gilroy Dispatch.
What was the response to your warning after the Loma Prieta earthquake struck? The authorities wanted my head and I was suspended for 2½ months. I’d been predicting quakes since 1974 ... and I’d never had that kind of response.
How regularly do you publish earthquake predictions? When I found out I could predict them in 1974, it was quite rewarding intellectually, so I started issuing annual predictions. In the ’80s, I started making predictions every month.
Animals give you clues to pending quakes. What animal signs tipped you off in 1989? There were 27 ads for missing cats and 58 missing dog ads — these were unprecedented numbers. Baby beaked whales had beached themselves in San Francisco, a very rare pygmy sperm whale washed up in Santa Cruz and homing pigeons were getting lost.
You also rely on the moon for predictions. When are quakes most likely? Once a month when the moon is at its closest point, and twice a month when it’s lined up with the sun and the Earth.
Are we in a danger period right now? October tends to be one of the most active months for earthquakes in the Bay Area. March, April and October are associated with the equinox and they are the big months for earthquakes.
— John Upton