When a wildfire or someone else's carelessness sets up an earth movement loss, California asks one question: what was the efficient proximate cause, meaning the predominant cause, not simply the last one in time?

Wildfire and mudslide: when a loss results from a combination of perils including a landslide, mudslide, mudflow or debris flow, coverage must be provided if an insured peril is the efficient proximate cause, under the same terms as for that peril (Section 530.5). A fire that strips a slope can be that cause even if it never touches the house. California does not split the loss between the perils.

Policy wording cannot override this. Exclusions are unenforceable to the extent they conflict with Section 530 and the efficient proximate cause doctrine, so "regardless of any other cause" language cannot bar coverage when a covered peril was the efficient proximate cause. This does not void every exclusion: in Julian, the insurer could deny a loss whose efficient proximate cause was a rain-induced landslide.

Negligence of others: under Garvey, if earth movement was the efficient proximate cause, coverage is denied; if third-party negligence, such as a contractor's poor compaction, was the efficient proximate cause, coverage exists, unless the policy separately excludes it, as many forms do for faulty workmanship. Even when her own insurer properly denies a claim, the homeowner can still sue the negligent party: California makes everyone responsible for injury caused by want of ordinary care in managing their property (Civil Code §1714(a)). If the insurer had paid, it could pursue that right through subrogation.