In Safeco Ins. Co. of America v. Fireman's Fund Ins. Co. (2007) 148 Cal.App.4th 620, a single primary insurer had issued a homeowner's liability policy, with policy limits of $ 500,000 per occurrence, and had then renewed it annually, so as to cover policy periods from 1997 through 2001. (Id. at pp. 626, 631.) In 1998, a landslide from the insured's property damaged several downhill properties. (Id. at p. 625.) Over the succeeding years, there was further damage as a result of the original landslide; for example, when it rained, "mud, debris, vegetation, and water ... continued to flow downhill." (Id. at p. 626.) Eventually, the insured was held liable for approximately $ 4 million in property damage. (Id. at p. 627.) The appellate court held that the primary insurer was liable for only $ 500,000. (Safeco Ins. Co. of America v. Fireman's Fund Ins. Co., supra, 148 Cal.App.4th at pp. 632-639.) It explained that there had been only one occurrence. (Id. at pp. 632-634.) It concluded: "Finally, we note that many comprehensive general liability policies obligate the insurer to '"pay on behalf of the insured all sums which the insured shall become legally obligated to pay as damages because of ... property damage ... ."' Because the insurer agrees to pay 'all sums,' the policy language may support an argument that the insured is entitled to the policy limits under successive policies even though there is only one occurrence. This argument, which could result in 'stacking' policy limits, has no application to the homeowners policy here, under which the insurer agreed to 'pay up to our limit of insurance, $ 500,000 per occurrence, for the damages for which the "insured" is legally liable.' (Italics added.) As we have discussed, there was only one occurrence in this case, entitling the insured to $ 500,000 in indemnity under the first policy." (Id. at p. 638.)