地震保険の仕組み: 保険料、免責額、保障範囲

The Basics of Earthquake Insurance Coverage

[[Earthquake-insurance]] is a specialized insurance product that pays for physical damage to your home, other structures on your property, and personal belongings caused by seismic ground shaking, 余震本震と同じ断層領域で本震の後に続く、より規模の小さい地震。余震活動は数週間から数年続くことがあり、最大の余震は通常本震よりマグニチュードが1.0〜1.2小さい。s that follow the main event, and in some policies, 地震誘発地すべり地震の揺れによって引き起こされる、土砂や岩石の斜面下方への移動。地すべりは地域全体を埋没させることがあり、揺れそのものより多くの犠牲者を出すこともある。s and 地盤増幅（サイト効果）軟弱な土壌や堆積層が地震波を増幅させることによって生じる、揺れの強さの増大。軟弱地盤上の構造物は、基盤岩上の構造物に比べて2〜10倍強い揺れを経験することがある。-related subsidence directly caused by an earthquake. Understanding the mechanics of how these policies are structured will help you avoid surprises when you need the coverage most.

Unlike health or auto insurance, earthquake policies are not bundled into standard homeowners or renters policies. In most states, you must purchase it as a separate endorsement added to your existing policy or as a standalone product from a specialty insurer. In California, the primary source for residential earthquake insurance is the California Earthquake Authority (CEA), a publicly managed nonprofit that works through participating insurers.

Deductibles: The Most Important Number

The 地震保険の自己負担額（控除額）保険適用が開始される前に契約者が自己負担しなければならない、保険評価額に対する割合。地震保険の自己負担額は通常10〜25%で、一般的な保険の免責額よりはるかに高い。 is the single most important feature differentiating earthquake insurance from other insurance products. While typical homeowners policies have flat dollar deductibles of $500 to $2,500, earthquake deductibles are expressed as a percentage of the insured dwelling value — commonly 10%, 15%, or 20%. On a home insured for $400,000, a 15% deductible means you pay the first $60,000 in repair costs out of pocket before insurance pays anything. This percentage structure exists because post-earthquake claims are extraordinarily large and numerous, making flat deductibles economically unworkable for insurers.

The deductible calculation applies separately to different coverage components. If your home sustains $80,000 in structural damage and a 15% deductible applies to your $400,000 dwelling value, the deductible is $60,000 and insurance pays $20,000. Your personal property coverage may carry its own separate deductible, often 5–25% of the personal property limit. Understanding this structure before purchasing helps you choose appropriate coverage limits and reserve adequate emergency funds to cover your deductible obligation.

Coverage Components

A standard earthquake policy covers four main components. Dwelling coverage pays for structural repairs to your home — cracked foundations, collapsed chimneys, broken walls, and damaged roofing systems. Other structures coverage extends to detached garages, fences, and outbuildings. Personal property coverage compensates for furniture, appliances, clothing, and electronics destroyed or damaged in the earthquake. Additional living expenses (also called loss of use) coverage pays for temporary housing, meals, and other costs you incur while your home is being repaired or rebuilt.

Each component has its own sub-limit, and policyholders frequently discover after an earthquake that their personal property or loss-of-use limits are inadequate. The 1994 Northridge earthquake revealed that many affected homeowners were underinsured because they had not updated their dwelling coverage to reflect rising construction costs. Insurers recommend reviewing coverage limits every two to three years and after any significant home renovation or improvement.

What Is Not Covered

Earthquake policies contain important exclusions. Damage from fire following an earthquake is typically covered under your standard homeowners policy, not the earthquake policy. [[Tsunami]] damage is excluded from earthquake policies and is typically covered only under the National Flood Insurance Program (NFIP), creating a significant gap for coastal homeowners. [[Liquefaction]] damage — where saturated soil loses strength and flows, causing foundations to sink or tilt — occupies a gray area: some policies cover it explicitly, others exclude it as earth movement unrelated to the earthquake event. Read your policy language carefully and ask your agent directly about these scenarios.

Vehicles damaged in an earthquake are covered under your auto insurance's comprehensive coverage, not your earthquake policy. Sinkholes, 地震誘発地すべり地震の揺れによって引き起こされる、土砂や岩石の斜面下方への移動。地すべりは地域全体を埋没させることがあり、揺れそのものより多くの犠牲者を出すこともある。s not directly triggered by the earthquake, and pre-existing structural deficiencies are also commonly excluded.

Premiums: How Much You Pay

Earthquake insurance premiums vary enormously based on geographic location, home construction type, age, square footage, coverage limits, and deductible level. In California, annual premiums typically range from $800 to $3,000+ for a standard single-family home. In lower-risk states like Texas or Florida, earthquake coverage can often be added for $100–$400 per year. In the Pacific Northwest, premiums for Seattle or Portland homes have risen significantly as seismic risk awareness has increased, often falling in the $1,500–$4,000 range.

The 予想最大損失額（PML）単一の地震事象によって、保険ポートフォリオや不動産が被る可能性のある最大損失額の推定値。保険会社・再保険会社にとって重要な指標。 concept underlies insurer pricing. Actuaries estimate the maximum loss an insurer would likely pay across its portfolio in a major earthquake scenario and price premiums to ensure adequate reserves. Choosing a higher deductible directly reduces your premium — moving from a 10% to a 20% deductible can cut premiums by 30–50% — but transfers more financial risk back to you. The right balance depends on your liquid reserves and risk tolerance.

Policy Limits and Replacement Cost

Policies may pay claims on either an actual cash value (ACV) or replacement cost basis. ACV policies depreciate the value of damaged items — a ten-year-old kitchen pays out at its current depreciated value, not the cost to install a new kitchen. Replacement cost policies pay the actual cost to repair or rebuild without depreciation. Replacement cost coverage costs more but provides substantially better protection. For a home in a high-risk zone, the difference between ACV and replacement cost coverage could represent tens of thousands of dollars in a major claim.