Nankai Trough

nankai-trough-mcp

Nankai Trough (南海トラフ地震) earthquake hazard and building-safety engine for AI assistants. Ask "how bad is the Nankai Trough quake, how far does it reach, and what does that mean for a house built in 1978?" and get official Japanese government figures, every one cited and dated, with a route to the official maps for your exact address. It never tells you you're "safe."

It reports what 内閣府 (Cabinet Office), 地震本部, 気象庁, and 国土交通省 actually publish, and where a figure isn't verifiable, it points you at the source instead of inventing one. Bilingual EN/JA. Runs locally, no API keys.

Live companion map: https://nankaitrough.bymarsel.me (this is the open data engine behind it, the same official data as an explorable map).

⚠️ Not a prediction, not a verdict. This explains official data and routes you to official guidance and a professional seismic diagnosis (耐震診断). Always confirm with your municipality and official hazard maps. In an emergency, follow official evacuation instructions.

Why it exists

Most people underestimate the *reach*. The 30-year probability was revised by 地震本部 in September 2025 away from the old single "80%" to a two-model range (60–90%+ (higher model) / 20–50%). Intensity-7 shaking is projected across 10 prefectures, and 764 municipalities in 31 prefectures face major shaking or a 3 m+ tsunami. "I'm inland, so I'm fine" is exactly the assumption this corrects.

The authoritative data is real, but it's scattered across five agencies and mostly buried in PDFs. This server makes it cited and usable from an AI assistant, without ever inventing a number.

The attitude: assume the worst

The earthquake is unknown, and claiming we know is an illusion. So the refusal here is one-directional: the tools will alarm you with official numbers, and they will never reassure you.

Where the official model publishes several cases, the severe one leads. A low probability is reported as a floor, not a ceiling, and is never relayed as good news. location_probability will tell you the government puts your mesh at a 12% chance of 震度6強 in 30 years; it will not tell you that means you are fine.

If you cannot write Japanese

The official geocoder only reads Japanese addresses, which would have excluded the people this server is for. Give a 7-digit postal code instead and every address-taking tool resolves it through Japan Post data:

232-0063        2320063        〒232-0063

That lands on the centre of your postal district rather than your building, and the tools say so in the response rather than pretending to more precision than they have. All output is available in English with language: "en".

Data rules

• No verdicts. It reports official figures + plain-language meaning, never "your home is safe/unsafe."
• Every figure cites its official source + date. If a value isn't verifiable in a primary source, it points to the source instead of guessing.
• Probabilistic ≠ scenario. J-SHIS (all-source probability) is never presented as the Nankai scenario (Cabinet Office).
• Building safety can't be looked up. It's classified from the build year + structure *you* provide. No fabricated per-building data.

Install

claude mcp add nankai -- npx -y nankai-trough-mcp

JSON config

The server config is the same across clients; only the file path differs.

Claude Code: ~/.claude/.mcp.json

{

"mcpServers": { "nankai": { "command": "npx", "args": ["-y", "nankai-trough-mcp"] } } }

Cursor: ~/.cursor/mcp.json

{

"mcpServers": { "nankai": { "command": "npx", "args": ["-y", "nankai-trough-mcp"] } } }

VS Code (GitHub Copilot): .vscode/mcp.json

{

"servers": { "nankai": { "type": "stdio", "command": "npx", "args": ["-y", "nankai-trough-mcp"] } } }

Claude Desktop: claude_desktop_config.json

{

"mcpServers": { "nankai": { "command": "npx", "args": ["-y", "nankai-trough-mcp"] } } }

Config path:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

From source

git clone https://github.com/mrslbt/nankai-trough-mcp.git

cd nankai-trough-mcp npm install && npm run build

Point the client config at the built entry:

{ "command": "node", "args": ["/absolute/path/to/nankai-trough-mcp/dist/index.js"] }

Tools

Prompts: assess_home_earthquake_risk, nankai_briefing.

Resources

Read-only reference documents a client can list and read without a tool call. Each is rendered from the same data the tools use, so they never drift out of sync.

Example prompts

Brief me on the Nankai Trough earthquake: the scale, the reach, and what

intensity 7 actually means for a building.

My house is in 高知市本町. Give me the official hazard maps for my address's predicted shaking and tsunami.

I live in a wooden house built in 1978. What seismic standard is that under, and what should I do about it? Don't tell me whether it's safe.

Walk me through assessing my home's earthquake risk: 静岡市葵区追手町9-6, built 1990, reinforced concrete.

Scope

This server does not compute its own per-address values. Two different things follow from that:

• It reports official published per-mesh probabilities (location_probability, J-SHIS Y2024). Surfacing a government figure is not inventing one.
• It bridges to the official maps for the Nankai scenario at an address (official_hazard_maps). That data lives in bulk Cabinet Office GIS files needing an ingestion pipeline, and faking it is not on the table.

Headline figures (and where they come from)

Every figure below is verified against the primary government source and carries an as-of date in the tool output. See src/data/nankai.ts for the full verification log.

Sources & license

Official data is used as derived output with attribution; raw government files are never re-hosted.

出典：内閣府 南海トラフの巨大地震モデル・被害想定検討会 ／ 地震調査研究推進本部 ／ 気象庁 ／ 国土交通省（住まいの耐震化）／ 国土地理院（地理院タイル・ジオコーディング）／ 住宅リフォーム推進協議会。

日本語

南海トラフ地震のハザードと建物の耐震性を、公的データだけで扱うMCPサーバーです。内閣府・地震本部・気象庁・国土交通省の公表値を、出典と日付つきで提示し、あなたの住所の正確な想定震度・津波は公式ハザードマップへ橋渡しします。建物の安全性は「安全／危険」と判定せず、建築年と構造から耐震基準の世代を示し、耐震診断・補助制度へ案内します。ローカル動作、APIキー不要。

Disclaimer

This server surfaces official Japanese government data and explanations. It is not a prediction, not a verdict on whether you or your home are safe, and not a substitute for official evacuation guidance or a professional seismic diagnosis (耐震診断). Figures are approximate and as reported by their official sources; always confirm at the source. Unofficial, not affiliated with any government agency.

License

MIT

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Built by Marsel Bait in Tokyo