In the wake of the Mexico City earthquake, the major topic of conversation here, naturally enough, has been the ability of this metropolis to withstand a similar quake.

The odds are good, authorities say, because the building code is tougher here and Angelenos are inured to danger because of their daily testing on the freeways. So even when it is hit by "the Big One," as local TV calls the super-quake that is expected some time in the next few decades, Los Angeles will survive.

That is the good news. The bad news is that the longer Los Angeles is around, the weirder it gets.

A family medical emergency has made me a short-term resident of Los Angeles, and I am here to testify that this city is really strange. Did you know, for example, that you cannot walk in Los Angeles? The sidewalks are simply traps for unwary tourists.

Only four forms of locomotion are acceptable in Los Angeles: driving a car, pedaling a bicycle, riding a skateboard and jogging. Walking is out.

The other evening after dinner, I was walking down Wilshire Boulevard from one apartment building to another as a steady stream of traffic whizzed past. The sidewalk was empty and well-lighted and I felt no sense of danger.

Then a cop pulled up. In the tone of a skeptical TV detective, he inquired, "Everything all right, Mister?"

"Yes, sir," I said. "Why do you ask."

"Well," he said, as if it were obvious, "you were walking."

It is just not done here. Last week, a new theater complex opened in a renovated bank building in a downtown neighborhood that had become blighted in the past decade. A Los Angeles Times reporter, seeking to assure readers that the area was safe, wrote that he had walked over to the theater from the newspaper office without incident. Nobody I talked to believed him. He said he had walked.

On those rare occasions when one Angeleno spots another walking, the walker invariably breaks into a jog. It is a little hard on the senior citizens, but they know their duty. And it's not as if they were being asked to skateboard.

To avoid the embarrassment of being caught walking, most people in Los Angeles try to spend their waking hours in their cars. Only two kinds of cars are eligible for licensing here: foreign cars and limousines. Foreign cars predominate but, from what I have seen, limousines are coming up fast. I am told by authorities that the last confirmed sale in Los Angeles of an American-made non-limousine occurred in 1979. The vehicle was licensed to a man named Jerry Brown who said he was running for president. No one speaks of him now.

The automobile shapes every aspect of Los Angeles life. Homes do not have front doors; they have car ports. Stores are similarly designed to discourage pedestrian traffic. The drugstore across Wilshire from the hospital where I have been hanging out cannot be entered from the sidewalk. To get in, you must pretend you have a car, go around in back, cut through the parking lot and hope no one reports you to the manager as a walker.

The drug store conforms to the two basic provisions of the Los Angeles zoning code for all commercial establishments. The first rule is that the floor space must equal or exceed that of the Los Angeles Coliseum, which seats 92,000 people. Just as no building in Washington may be higher than the Capitol, no store in Los Angeles may be smaller than the Coliseum. The second provision, based on the design principle of the famous Los Angeles freeways, is that whatever the volume of customer (or passenger) traffic, no more than two check-out lines (or off-ramps) are permitted.

Outsiders may think these two rules guarantee perpetual congestion, and Los Angeles is in fact the only city I know where freeway traffic reports are broadcast -- and needed -- at 8:30 on Sunday morning. But the forced congestion serves a much more important social function. It is only by trapping Angelenos on freeways or in supermarkets that they ever get to speak to each other. People tell me it's hard to discuss the Strategic Defense Initiative on skateboards.

But the check-out lines at any drugstore or supermarket move slowly enough for romances to be born and nurtured -- and for debate to be conducted in a wonderul variety of dialects. The check-out lines can be frustrating if you're in a hurry. No one uses cash in Los Angeles. They write checks, but they refuse to mar the see-through aesthetics of the skimpy clothing in which they shop by carrying the required identification cards, although two or three would be helpful. So the lines move slowly.

I hate to think what either the freeways or the shopping centers would be like when the Big One hits. But I learned an important technique for survival the other morning.

I was at the super-drugstore when a man walked in with a parrot on his shoulder. No one else seemed to think this odd, but I watched him closely as he bought some light bulbs and then boldly walked to the head of the check- out line, paid for them and walked out.

"What gives?" I asked the man ahead of me in line.

"The parrot," he said, lifting his eyebrows expressively. "You know . . . he needed to get out."

My advice is, before the Big One hits L.A., buy yourself a parrot. He'll get you out.