# 📐 L2 Spec — Ambient-Noise Tomography — Green-function retrieval Mismatch-Only Spec
**ID:** `L2-277-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-277`](/artifact/l1/L1-277)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554054
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| N days | — | 7 – 3650 |
| Snr db | dB | 0 – 40 |
| N freqs | — | 1 – 50 |
| N stations | — | 5 – 5000 |
| Scattering unmodelled | — | 0.0 – 0.3 |
| Station pair imbalance | — | 0.0 – 0.3 |
| Source distribution nonuniform | — | 0.0 – 0.5 |
## 2. Tolerance (ε)
**Type:** `fn`
```
2.0 + 8.0*source_distribution_nonuniform + 5.0*station_pair_imbalance + 5.0*scattering_unmodelled
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`afd8b7eb0ee6c44f4b3877a55fd156168a9cd27f9253adb0fb4546c93978cda8`
## 5. On-chain Registration
- **Chain hash:** `0x4bfea55e5b76786d91a7fa1c4ac87719f0e58ff5ec51c538ff6f8631281bf91d`
- **Chain tx hash:** `0xc1cf6e029eb4b2a8b64dd399d0f9b8c0e1bf734a99a1e530117261079de7bb43`
- **Chain block:** `41554054`
---
## File Mapping
This bundle consists of: `L2-277-001.md`, `L2-277-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-277-001.md` | Source of truth — edit this | Human or LLM |
| `L2-277-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-277-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._