name	verify-dark
description	Verify dark earthquake claims against fault databases. Use when checking if a candidate earthquake is truly "dark" (unmapped fault) or just pre-historical (known fault). Triggers on "verify dark", "check fault database", "is this dark", "audit earthquake claim".

/verify-dark - Fault Database Verification Skill

Purpose

Verify if a candidate "dark earthquake" claim is truly dark (unmapped source fault) or pre-historical (known fault, no written record). This skill automates the DARK_EARTHQUAKE_AUDIT.md workflow.

Usage

/verify-dark <lat> <lon> <date_CE> [region]

Examples:

/verify-dark 44.2 8.1 1394 italy
/verify-dark 32.7 -117.2 1741 california
/verify-dark -16.5 -44.8 96 brazil
/verify-dark 22.4 -84.0 1400 caribbean

Workflow

Step 1: Identify Region & Databases

Based on coordinates, determine which fault databases to check:

Region	Primary Database	Secondary Databases
Italy	DISS v3.3.1 (INGV)	ITHACA, EFSM20, GEM SHARE
California	SCEC CFM v7.0	CGS FER, USGS Quaternary
Caribbean/C. America	GEM CCAF-DB	USGS
Brazil	GEM SARA	(Note: Brazil EXCLUDED from SARA)
Middle East	EMME	GEM, Hessami (2003)
Romania	RODASEF	ESHM20, SHARE
Turkey	AFAD	GEM, Emre et al.

Step 2: Search Fault Databases

For each database, search within 50km and 100km radius:

Use calc_distance MCP tool to compute distances from candidate to known faults
Query database (WFS endpoint if available, or web search for geojson)
Record all faults found with strike, slip type, distance

Example search pattern:

# Check DISS v3.3.1 for Italy
WebFetch: https://diss.ingv.it/diss330/download/DISS330_ISS.geojson
Filter: features within 100km of (lat, lon)

# Check SCEC CFM for California
WebFetch: https://www.scec.org/research/cfm
Search for fault traces near coordinates

Step 3: Check Recent Literature (2010+)

Search for recent fault mapping publications:

WebSearch: "[region] fault mapping [year range]"
WebSearch: "paleoseismic trench [fault name]"
WebSearch: "[coordinates] seismogenic source"

Look for:

New fault discoveries
Offshore/submarine fault extensions
DEM-based lineament studies
Paleoseismic trenching results

Step 4: Run DEM Lineament Check (if available)

If DEM data exists for the region:

Check dem_tiles/ for existing analysis
Reference DEM_LINEAMENT_FINDINGS.md or similar
Note any unmapped structures identified

Step 5: Generate Verification Table

Create markdown table summarizing findings:

| Database | Checked | Faults within 50km | Faults within 100km | Notes |
|----------|---------|-------------------|---------------------|-------|
| DISS v3.3.1 | ✅ | [fault names] | [fault names] | [details] |
| ITHACA | ✅ | ... | ... | ... |
| EFSM20 | ✅ | ... | ... | ... |
| GEM | ✅ | ... | ... | ... |
| Recent lit | ✅ | ... | ... | [citations] |

Step 6: Classify Event

Based on findings, classify as:

Classification	Criteria
TRUE DARK	No mapped fault in ANY database (like Italy 1394, Brazil events)
PRE-HISTORICAL	Known fault exists, but earthquake predates written records (like California 1741)
PRE-COLUMBIAN	Event in Americas before 1492 (no records possible)
PRE-INSTRUMENTAL	Event before seismometer network (varies by region)
VALIDATION	Known earthquake used to test methodology (like Cuba 1766)
DATABASE ARTIFACT	"Missing" due to incomplete database, fault IS mapped elsewhere

Step 7: Update DARK_EARTHQUAKE_AUDIT.md

Add new section to paleoseismic_caves/DARK_EARTHQUAKE_AUDIT.md:

### ✅ [Region]: [Date] - **[CLASSIFICATION]**

**Date verified**: [today's date]
**Classification**: **[CLASSIFICATION]** ([explanation])

**Databases checked**:
- ✅ **[Database 1]** - [findings]
- ✅ **[Database 2]** - [findings]
...

**Key findings**:
[Summary of what was found]

**Conclusion**: [Why this classification]

**Likelihood of database artifact**: **[HIGH/LOW/ZERO]** - [explanation]

Classification Decision Tree

Is there a mapped fault within 100km in ANY database?
├─ YES → Is earthquake in historical catalogs?
│        ├─ YES → VALIDATION EVENT
│        └─ NO → PRE-HISTORICAL (known fault, no record)
│                 └─ If Americas pre-1492 → PRE-COLUMBIAN
│                 └─ If pre-seismometer → PRE-INSTRUMENTAL
└─ NO → Does a fault database exist for this region?
         ├─ NO (e.g., Brazil) → TRUE DARK (no database = genuine gap)
         └─ YES → Did DEM analysis find unmapped structure?
                  ├─ YES → TRUE DARK (candidate)
                  └─ NO → UNATTRIBUTED (needs more research)

Output Format

The skill will output:

Summary box at top with classification
Verification table with all databases checked
Key findings with quotes/evidence
Classification rationale explaining decision
Update to DARK_EARTHQUAKE_AUDIT.md (with approval)

Database URLs Reference

Italy:

California:

SCEC CFM: https://www.scec.org/research/cfm
CGS FER: https://maps.conservation.ca.gov/cgs/fer/

Caribbean:

GEM CCAF-DB: https://github.com/GEMScienceTools/CCAF-DB

Middle East:

EMME: https://www.emme-gem.org/

Global:

GEM Global Active Faults: https://github.com/GEMScienceTools/gem-global-active-faults

Important Notes

USGS Quaternary Fault Database has 9-27 year lag - never use as sole source
Brazil is excluded from GEM SARA - stable continental interiors have no fault databases
"Dark" means UNMAPPED FAULT, not just "no written record"
Always check 3+ databases before classifying as TRUE DARK
DEM lineament analysis strengthens case for unmapped structures

verify-dark

Install Skill

SKILL.md