Volcanic Check

/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)

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

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

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)

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

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