Mudslide After Wildfire: Why Earth Movement Is Covered When Fire Is the Cause

A wildfire burns through the hills above your home. Weeks or months later, the first heavy rain arrives — and with it, a wall of mud, debris, and boulders. The hillside, stripped of the vegetation that held it together, collapses onto your property. Your home is damaged or destroyed — not by flame, but by earth movement triggered by the fire that came before it.

You file a claim. The adjuster reviews your policy and points to the earth movement exclusion — the standard language that excludes landslides, mudflow, and earth settling from coverage. On the face of the policy, it looks like the insurer has a textbook basis to deny.

But in California, this is not how it works. When a wildfire is the reason the hillside failed — when fire is the event that set the entire chain in motion — the earth movement exclusion does not control. The California Department of Insurance has taken this position formally, California courts have established the legal framework that supports it, and insurers operating in this state have largely followed that reasoning. This article explains why.

The Earth Movement Exclusion: What the Policy Says

Standard homeowner policies exclude earth movement. The language varies slightly between carriers, but the typical exclusion reads something like:

“We do not insure for loss caused directly or indirectly by… earth movement, including but not limited to earthquake, landslide, mudflow, mudslide, sinkhole, subsidence, erosion, or any other earth movement…”

Read in isolation, this language appears to exclude exactly the kind of loss we are discussing: a mudslide or debris flow that damages your home. And in many states, this exclusion would end the conversation. But California is not most states, and the analysis does not stop at the exclusion language.

The critical question is not what caused the damage in the final moment of impact. The question is what set the chain of events in motion. If the answer to that question is a wildfire — a covered peril under every standard homeowner policy — then California law dictates that the loss is covered despite the earth movement exclusion.

The Efficient Proximate Cause Doctrine

The legal foundation for this result is the efficient proximate cause doctrine — a principle deeply embedded in California insurance law. Under this doctrine, when a covered peril sets in motion a chain of events that ultimately produces a loss through an excluded peril, the loss is covered. The covered peril need not be the last event in the chain. It need not be the event that physically struck the house. It must be the predominant or movingcause — the event that set everything else in motion.

The foundational California authorities are well established:

• Sabella v. Wisler (1963) 59 Cal.2d 21: The California Supreme Court established the efficient proximate cause doctrine in the insurance context. Where a covered peril is the moving cause of a loss, coverage exists even when an excluded peril is part of the causal chain.
• Garvey v. State Farm Fire & Casualty Co. (1989) 48 Cal.3d 395:The California Supreme Court reinforced and refined the doctrine. The court confirmed that the efficient proximate cause analysis applies even when the policy contains an explicit exclusion for one of the concurring causes — and that insurers cannot use policy language to override this rule.
• California Insurance Code § 530:“An insurer is liable for a loss of which a peril insured against was the proximate cause, although a peril not contemplated by the contract may have been a remote cause of the loss; but he is not liable for a loss of which the peril insured against was only a remote cause.”
• Julian v. Hartford Underwriters Ins. Co. (2005) 35 Cal.4th 747: An important clarification. The Supreme Court held that the efficient proximate cause doctrine applies when there is a single causal chain— one peril triggering another. When two truly independent perils operate concurrently, the analysis may differ. This distinction matters because insurers sometimes argue that the rainfall was an “independent” cause rather than a link in the chain that fire started.

For a deeper discussion of the efficient proximate cause doctrine and how it applies across different types of claims, see our article on engineering reports vs. coverage determinations, which includes detailed analysis of Sabella, Garvey, Insurance Code § 530, and CACI 2306.

The Causal Chain: Fire to Mudslide

The factual pattern in post-wildfire mudslide claims follows a clear and well-documented sequence:

1. Wildfire burns through hillside terrain. The fire destroys vegetation, root systems, and organic material that hold soil in place. Intense heat can also create a hydrophobic (water-repellent) layer in the soil, which prevents water from absorbing into the ground as it normally would.
2. The hillside becomes unstable. Without vegetation to anchor the soil and with a hydrophobic layer preventing water infiltration, the burn scar area becomes extraordinarily vulnerable to erosion and mass movement.
3. Rainfall arrives. Precipitation that the hillside would have absorbed before the fire now runs off the surface, picking up soil, rock, and debris as it moves downhill.
4. Mudslide, debris flow, or earth movement strikes the property.The resulting flow — which can include boulders, fallen trees, sediment, and flood water — damages or destroys homes in its path.

This is a single causal chain. Fire was the event that destabilized the hillside. Rain was the mechanism that mobilized the destabilized soil. The mud, debris, and earth movement were the physical results. Without the fire, the hillside would not have failed. The efficient proximate cause of the loss was the wildfire — a covered peril.

The CDI’s Position: Earth Movement Claims After Wildfire

The California Department of Insurance has formally addressed this issue. Following the catastrophic January 2018 Montecito debris flows — which killed 23 people and destroyed over 100 homes after the December 2017 Thomas Fire denuded the hillsides above the community — the CDI issued guidance to insurers stating that claims for debris flow and mudslide damage should be evaluated under the efficient proximate cause doctrine. The CDI’s position is straightforward: if the Thomas Fire was the efficient proximate cause of the vegetation loss that led to the debris flows, those claims should be covered under the fire and wildfire coverage in the homeowner policy.

This was not a novel legal theory. The CDI was articulating what Sabella, Garvey, and Insurance Code § 530 already required. But the formal guidance served an important purpose: it put insurers on notice that the Department expected compliance and that improper denials based on the earth movement exclusion — when wildfire was the efficient proximate cause — would be treated as potential violations of the Fair Claims Settlement Practices Regulations.

The CDI has reinforced this position after subsequent wildfire seasons. Following the 2018 Camp Fire and Woolsey Fire, the 2020 fire season, and most recently after the January 2025 Palisades and Eaton fires, the Department has reaffirmed that the efficient proximate cause doctrine applies to post-wildfire earth movement claims and that insurers denying these claims on earth movement exclusion grounds face scrutiny under California’s unfair claims practices laws.

Anti-Concurrent Causation Clauses: Why They Don’t Apply Here

If you have read other articles on this site, you have seen the anti-concurrent causation (ACC) clause discussed in several contexts. The standard ACC language appears at the beginning of the exclusions section in most modern homeowner policies:

“We do not insure for loss caused directly or indirectly by any of the following. Such loss is excluded regardless of any other cause or event that contributes concurrently or in any sequence to the loss.”

In states that enforce this language, an insurer could argue that because earth movement was “in the sequence” of events, the entire loss is excluded — even though fire started the chain. The ACC clause would override the causal analysis and deny coverage based solely on the presence of an excluded peril somewhere in the sequence.

California does not enforce anti-concurrent causation clauses. The California Supreme Court in Garvey established that the efficient proximate cause doctrine cannot be overridden by policy language. ACC clauses are unenforceable in California because they conflict with the efficient proximate cause rule established in Sabella and Garveyand codified in Insurance Code § 530. An insurer cannot contractually eliminate the efficient proximate cause analysis by inserting ACC language into the policy.

For a detailed discussion of ACC clauses, their enforceability in different states, and why California rejects them, see our articles on engineering reports vs. coverage and wear and tear as a cause of loss. Both articles explain the ACC framework and why California’s rejection of it matters for policyholders. Our guide on pre-existing damage vs. storm damage also discusses the concurrent causation analysis in the context of storm claims where insurers attempt to attribute damage to pre-existing conditions.

Why This Is California-Specific

It is important to understand that this analysis reflects California law. The efficient proximate cause doctrine as described here, and particularly the unenforceability of ACC clauses, is not universal. A handful of other states — including Washington, West Virginia, and North Dakota — have similarly refused to enforce ACC language. But in the majority of states, ACC clauses are enforceable. In those jurisdictions, an insurer can deny a post-wildfire mudslide claim based on the earth movement exclusion, and the ACC language prevents the policyholder from arguing that fire was the predominant cause.

This difference is enormous. In an ACC-enforcing state, the insurer does not need to prove that earth movement was the predominant cause. It only needs to show that an excluded peril contributed “in any sequence” to the loss — a far lower bar. The efficient proximate cause analysis that protects California policyholders does not exist in those jurisdictions. If you are dealing with a post-wildfire earth movement claim outside of California, consult with a qualified attorney in your state who understands your jurisdiction’s position on concurrent causation.

Beyond Mudslides: Other Post-Wildfire Secondary Perils

The efficient proximate cause analysis is not limited to mudslides. The same framework applies to other forms of damage that occur in the aftermath of a wildfire when the fire was the event that created the conditions for the subsequent loss:

• Debris flows: Faster-moving and more destructive than mudslides, debris flows carry boulders, trees, and structural debris down burn-scarred slopes. The same causal chain applies: fire destroyed the vegetation, rain mobilized the material, the debris flow struck the property.
• Boulder strikes: Large rocks that were held in place by vegetation and root systems can be dislodged after a fire removes that natural anchoring. A boulder rolling downhill and striking a home after a wildfire is earth movement with fire as the efficient proximate cause.
• Erosion and hillside failure: Gradual or sudden erosion of burn-scarred slopes that undermines foundations, retaining walls, or driveways. If the erosion would not have occurred but for the fire, the same analysis applies.
• Flooding from burn scars: Hydrophobic soil conditions created by intense fire heat can cause flash flooding in areas that were not previously flood-prone. While flood is separately excluded, the efficient proximate cause analysis may apply when fire created the conditions that made flooding possible.

In each case, the framework is the same: identify the event that set the chain in motion. If it was a covered peril, the loss should be covered under California law. For more on wildfire claims generally — including smoke contamination, coverage breakdowns, and insurer tactics — see our California wildfire claims guide. For claims involving heat and radiant damage from nearby fires without direct flame contact, see our article on thermal and heat damage from nearby wildfires.

What to Do If Your Post-Wildfire Earth Movement Claim Is Denied

While most California insurers are handling these claims consistently with the CDI’s position, denials still occur. If your post-wildfire mudslide or earth movement claim is denied based on the earth movement exclusion, take these steps:

1. Request the denial in writing with specific policy language cited. Under California’s Fair Claims Settlement Practices Regulations, the insurer must identify the specific policy provision it is relying on. A blanket denial referencing “earth movement” without addressing the efficient proximate cause doctrine is inadequate.
2. Document the fire-to-mudslide causal chain. Gather evidence that the wildfire denuded the hillside and created the conditions for the subsequent earth movement. USGS debris flow hazard assessments, county geological surveys, Cal Fire burn perimeter maps, and National Weather Service post-fire warnings are all relevant evidence.
3. Cite the efficient proximate cause doctrine with the assistance of an attorney. An attorney experienced in insurance coverage disputes can reference Sabella v. Wisler, Garvey v. State Farm, Insurance Code § 530, and the CDI’s guidance in your response to the denial, making clear that California law requires the insurer to evaluate the predominant cause of the loss, not merely identify the last peril in the chain.
4. Address the ACC clause directly with attorney guidance. If the denial relies on anti-concurrent causation language, an attorney can respond that ACC clauses are unenforceable in California and cannot override the efficient proximate cause analysis.
5. File a CDI complaint if the insurer persists. If the insurer maintains its denial despite the applicable law, a complaint to the California Department of Insurance is appropriate. See our guide on filing a CDI complaint. The CDI has been particularly attentive to post-wildfire earth movement denials.
6. Engage a licensed Public Adjuster or attorney. These claims involve the intersection of complex causation analysis, policy interpretation, and regulatory requirements. A professional who understands both the technical and legal dimensions can build the case needed to overturn an improper denial.

The Montecito Example

The January 9, 2018 Montecito debris flows remain the most significant example of this issue in California. The Thomas Fire — at the time the largest wildfire in modern California history — burned through the mountains above Montecito in December 2017. Weeks later, an intense rainstorm struck the burn scar area. The result was catastrophic: massive debris flows carrying boulders the size of cars destroyed over 100 homes, damaged hundreds more, and killed 23 people.

These losses were caused by earth movement. There is no dispute about that. Mud, rock, and debris physically struck and destroyed the homes. But the earth movement would not have occurred without the Thomas Fire. The hillsides had held for decades through comparable rainstorms because intact vegetation and root systems stabilized the soil. Once the fire removed that vegetation, the hillsides were a catastrophe waiting for the next rain.

The CDI’s guidance following Montecito made clear that these claims should be evaluated under the efficient proximate cause doctrine with fire as the predominant cause. Insurers largely complied. The Montecito example established the practical template for how post-wildfire earth movement claims are handled in California — a template that has been applied in subsequent fire seasons and that remains in effect today.

Looking Ahead: The 2025 Fires and Burn Scar Risks

Following the January 2025 Palisades and Eaton fires in Los Angeles, thousands of acres of hillside terrain are now burn-scarred and vulnerable to post-fire earth movement. The USGS has already published debris flow hazard assessments for the affected areas, and the National Weather Service has issued post-fire flash flood and debris flow watches in advance of anticipated rainfall.

Homeowners in and below these burn scar areas should understand that if debris flows, mudslides, or other earth movement damage their property, the efficient proximate cause of that damage is the wildfire that destabilized the hillside. California law protects your right to coverage in this scenario. The CDI has reaffirmed its position, and the legal framework is well established. Do not accept a denial based solely on the earth movement exclusion without understanding your rights.