If you cannot locate your spouse and are seeking divorce, you are able to do so by filing a divorce by publication.
Proving a Lost Spouse
In order to pursue a divorce by publication you will need to prove to the court that you have searched for your missing r hiding spouse. This can be done through a number of means. You will need to provide the court with a signed Affidavit of Diligent Search that proves you have taken all actions possible to locate your spouse. This document proves you have exhausted your search, and the spouse can absolutely not be found.
Application for Publication of Summons
After submitting the Affidavit of Diligent Search you will need to file an Ex Parte (Without Notice) Application for Publication of Summons; Declaration of Petitioner in Support Thereof; Memorandum of Points and Authorities. Once the court approves this it will issue an Order of Publication, which allows the summons to be published. The summons will be published once a week for four successive weeks, with at least 5 days between successive publications.
Failure to Respond to Divorce by Publication
The missing spouse will have 30 days to file a response. If the missing spouse fails to respond, a Petitioner then files a Request to Enter Default Dissolution of Marriage. There is no final hearing and the divorce will be finalized six months after the first publication of the summons. While the court can grant the divorce, it cannot make decisions regarding child custody, child support, or division of property.
Source: 3 Step Divorce, California Divorce By Publication – Missing Spouse, 2014