/volcanic-check - Volcanic Correlation Analysis Skill

Purpose

Cross-reference speleothem anomalies with volcanic eruption records to rule out volcanic false positives. Critical for validating seismic interpretations.

Usage

/volcanic-check <year_CE> [--window YEARS] [--threshold VSSI]

Examples:

/volcanic-check 1275                    # Check around 1275 CE (±20 years default)
/volcanic-check 620 --window 50         # Wider window for uncertain dates
/volcanic-check 1394 --threshold 10     # Only major eruptions (>10 Tg S)

Volcanic Databases

Primary Source: eVolv2k

The eVolv2k database (Toohey & Sigl 2017) provides:

• Volcanic Stratospheric Sulfur Injection (VSSI) in Tg S
• Ice core dated eruptions back to 500 BCE
• Uncertainty ranges

Reference Eruptions (VSSI Rankings)

Rank	Year	Eruption	VSSI (Tg S)	Global Impact
1	1257	Samalas	59.42	Extreme (1258 famine)
2	1815	Tambora	26.03	"Year without summer"
3	1452	Kuwae	31.06	Major cooling
4	1230	Unknown	23.78	Significant
5	1108	Unknown	19.16	Significant
6	1809	Unknown	22.10	Pre-Tambora event
7	939	Eldgjá	18.81	Basaltic flood
8	536	Unknown (Ilopango?)	~15+	"Worst year to be alive"
9	1783	Laki	17.08	European famine
10	1286	UE6 (Unknown)	~10	Post-Samalas cluster

Workflow

Step 1: Define Search Window

Center: [input_year]
Window: ±[window] years (default ±20)
Search range: [input_year - window] to [input_year + window]

Step 2: Query eVolv2k Database

Search for eruptions in window:

### Volcanic Events Within ±20 Years of [YEAR] CE

| Year | Eruption | VSSI (Tg S) | Rank | Distance (years) |
|------|----------|-------------|------|------------------|
| 1257 | Samalas | 59.42 | #1 | -18 |
| 1286 | UE6 | ~10 | - | +11 |

Step 3: Assess Volcanic Forcing Potential

VSSI (Tg S)	Classification	Expected Speleothem Response
> 25	EXTREME	Strong δ18O negative, 2-4 year recovery
15-25	MAJOR	Moderate δ18O negative, 1-3 year recovery
5-15	MODERATE	Weak signal possible
< 5	MINOR	Unlikely to produce detectable signal

Step 4: Generate Correlation Report

## Volcanic Correlation Check: [YEAR] CE

### Search Parameters
- Center year: [YEAR] CE
- Search window: ±[WINDOW] years
- VSSI threshold: [THRESHOLD] Tg S

### Eruptions Found

| Year | Eruption | VSSI (Tg S) | Distance | Correlation Risk |
|------|----------|-------------|----------|------------------|
| [year] | [name] | [vssi] | [±N yr] | [HIGH/MOD/LOW] |

### Assessment

**Volcanic forcing detected**: YES/NO

**Correlation risk**: HIGH / MODERATE / LOW / NONE

**Recommendation**: [Interpretation guidance]

Correlation Risk Assessment

Risk Level	Criteria	Action
HIGH	VSSI > 15 Tg S within ±10 years	Likely volcanic false positive
MODERATE	VSSI 5-15 Tg S within ±10 years OR VSSI > 15 within ±20 years	Check proxy decoupling
LOW	VSSI < 5 Tg S OR > 20 years distant	Volcanic unlikely
NONE	No eruptions in window	Volcanic ruled out

Decoupling Test Integration

If volcanic eruption found, check anomaly coupling:

Volcanic signature: DECOUPLED (δ18O >> δ13C)
Seismic signature: COUPLED (δ18O ≈ δ13C)

If HIGH volcanic risk + DECOUPLED → VOLCANIC
If HIGH volcanic risk + COUPLED → Possible CVSE (compound event)
If LOW volcanic risk → Seismic interpretation valid

Known Volcanic False Positives (Yok Balum)

Period	δ18O z	δ13C z	Ratio	Volcanic Event	Classification
1273-1279 CE	-3.77	-1.18	3.2	1257 Samalas	VOLCANIC
1228-1238 CE	-2.93	-1.91	1.5	1230 Unknown	VOLCANIC
1105-1125 CE	-2.98	~-1.3	2.3	1108 Unknown	VOLCANIC

Example Full Output

User: /volcanic-check 1285

## Volcanic Correlation Check: 1285 CE

### Search Parameters
- Center year: 1285 CE
- Search window: ±20 years (1265-1305 CE)
- VSSI threshold: 5 Tg S

### Eruptions Found

| Year | Eruption | VSSI (Tg S) | Distance | Risk |
|------|----------|-------------|----------|------|
| **1257** | **Samalas** | **59.42** | **-28 yr** | **HIGH** |
| 1286 | UE6 | ~10 | +1 yr | MODERATE |

### Assessment

**Volcanic forcing detected**: YES

**Correlation risk**: **HIGH**
- 1257 Samalas (#1 eruption in 2000 years) is 28 years prior
- 1286 UE6 is 1 year after

**⚠️ WARNING**: This anomaly falls within the post-Samalas volcanic cluster period.

**Recommendation**:
1. Check proxy COUPLING - if decoupled (ratio > 2.5), likely volcanic
2. Check recovery time - if < 5 years, likely volcanic
3. If COUPLED + long recovery, may be CVSE (compound event)

For Italy 1285, this IS a known CVSE-1285 (volcanic + seismic + floods).

Special Cases

CVSE Detection

If volcanic + seismic indicators present:

CVSE requires ALL THREE:
1. Volcanic forcing (eruption in ice cores) ✓
2. Seismic signal (Mg/Ca or δ13C elevation) ✓
3. Hydrological expression (documented floods) ✓

If all three → CVSE (Compound Volcanic-Seismic Event)

Pre-536 CE Events

⚠️ Ice core dating less certain before 536 CE

• Add ±50 year uncertainty
• Cross-reference multiple records

Medieval Quiet Period (1000-1100 CE)

If anomaly in 1000-1100 CE:
- eVolv2k shows 55-70% below-average volcanic activity
- Volcanic false positive UNLIKELY
- Strengthens seismic interpretation (e.g., ~1075 CE Yok Balum)

MCP/Web Resources

Source	Use
eVolv2k	Primary volcanic forcing database
VSSI	Volcanic Stratospheric Sulfur Injection
Ice cores	GISP2, NGRIP, Law Dome
WebSearch	For eruption details, impacts

Important Notes

1. Samalas 1257 dominates - Any anomaly 1250-1280 CE is suspect
2. Decoupling is key - Volcanic = DECOUPLED, Seismic = COUPLED
3. Recovery time diagnostic - Volcanic 1-3 yr, Seismic 10-71 yr
4. CVSE is rare but real - Don't dismiss compound events
5. Absence of volcanic ≠ seismic - Must still show positive seismic indicators