Cal. Bus. & Prof. Code § 7830.1

It is unlawful for any person other than a geophysicist licensed under this chapter to stamp or seal any plans, specifications, plats, reports, or other documents with the seal or stamp of a licensed geophysicist, professional geophysicist, or licensed certified specialty geophysicist, or to use in any manner the title “registered geophysicist,” “professional geophysicist,” or the title of any registered certified specialty geophysicist, or any combination of the words and phrases or abbreviations thereof, unless the person is licensed, or licensed and certified, under this chapter.