John Roach in National Geographic:
Can the moon cause earthquakes? …James O. Berkland is a Glen Ellen, California-based geologist and editor of Syzygy—An Earthquake Newsletter. He believes the gravitational tugs of the moon, sun, and other planets can influence earthquake activity. Berkland said he has accurately predicted tremors based on factors such as syzygy…
Using syzygy and other factors—such as the number of cats and dogs listed in the lost and found in newspaper classified advertisements—Berkland said he accurately predicted several earthquakes, including the October 17, 1989 earthquake in San Francisco, California. Berkland said the number of cats and dogs reported missing goes up prior to an earthquake. The numbers went up significantly prior to the 1989 San Francisco quake, he said.