You have a very valid question. The answer is not as simple as circling areas on a La Jolla map. Soils engineers and "geo tests" are common enough to real estate transactions in La Jolla that seasoned agents should be able to guide and advise you.
There have been some well-publicized areas of hillside slipping; and several other areas where land or construction limitations are known by area agents and residents. If you have any doubt, get a "geo test" for peace of mind.
Soils tests are crucial to evaluating properties in this area, and an experienced agent will have seen testing results and will have discussed soils hundreds of times-- he or she be able to help you discern areas of concern, and will advise you of the best engineers to undertake this work.
The homes that I have sold over the years that have had soil issues were due to A: homeowner negligence (water issues) & B: poor quality fill soil (which again essentially is a water issue because the fill soil used absorbed water poorly).
This could happen anywhere. It also could be caused by human error.This is like asking what part of Florida should i avoid because of hurricanes. Or, what states should I avoid because of tornados.
Happy funding, Rudi