All shook up from the earthquake of Jan. 17 (6.7 on the Richter scale), Los Angeles residents have been contending ever since with aftershocks, including a shocking awareness that as for the Big One, or at least another Pretty Big One, it’s not a question of if but when. Taping a Today show appearance last spring, part-time California resident Meryl Streep claimed that at a dinner party five years earlier Shirley MacLaine had assured her ”there’s not going to be a major earthquake until the beginning of 1994.” ”That is so freaky” was Today cohost Katie Couric‘s credulous response; Streep agreed. Back in her anchor chair, Couric told the world that Streep had relayed other MacLaine prognostications, including that another P.B.O. would roil L.A. soil in November ’94. Oops. MacLaine’s spokesman insists that Shirley ”is not in the business of predicting earthquakes. It was a joke between her and Meryl Streep that got out of hand.” Still, Today‘s trustworthy Couric, who delivered the information straight-faced, wouldn’t joke about seismic events, would she? Her spokesperson says no way. Streep was not available for comment. Let the record show that her taped interview aired on April 1.