Thank you for your question about your cherry tree.  Cherry trees are a member of the Prunus family, whose members have a host of problems in the home garden.  Here is a link to an Extension article that lists just a few of them, but they all have leaf curling and browning symptoms.  The issue you raise that gives me pause is the "this is the third cherry tree that has died in this spot" one, because it may mean that you have a problem such as Verticillium wilt, a soil borne fungus that kills many plants, although typically over a longer period of time.  Planting the same susceptible plants there time after time is just a recipe for disaster.  ("If you always do what you've always done, you'll always get what you've always gotten!")

There are not too many articles that address the issue in California; however, this study would seem to suggest that it might be present in nurseries supplying cherries to commercial outlets.  But I cannot jump to that conclusion with the scant information I have.

So, I suggest you take some of the brown stems, together with your photographs, to your county Extension office, whose contact information can be found here.  Note that Master Gardeners are available only on Thursdays from 9:30 to 11:30 am.

I am sorry for the loss of your trees, and hope that your Extension Service can provide you with an analysis and treatment ideas.  If not, please don't hesitate to write back.  Good luck!