Based on a quick answer from Perplexity it seems like there would be no issue with you buying the home and collecting passive income, but you may not be allowed to manage it yourself since that is considered active work.

Separate issue is only 13% of CA homeowners pay for earthquake insurance because it's so expensive and the deductible can be really high.What are your re-building costs in your area?

I also wouldn't touch hilltop with a 10' pole. struggled. old homes, over budget renovations, lots of issues. realtors push people here since it's the only place cheap houses close to downtown can be good but homes are 1900-1920.

There are large areas in the direction of the flight paths that do not have dense populations so it’s mostly a non-issue.

You could leverage the value of the entire four plex to put towards a larger asset or try to 1031 exchange it. again, i am no expert but I would consider myself a fairly savvy investor.

Better than underground homes which have issues with moisture etc.

Feel free to inquire about their staff qualifications if it's a larger organization.2.

Feel free to inquire about their staff qualifications if it's a larger organization.2.

Any repair issues the new acquisition has you will feel to much greater magnitude due to the property carrying a lot of debt.

. - Just be prepared, because a motivated seller typically has a property with issues you need to be sure you can solve.