基础设施级联分析

1. Start at source node (e.g., "cable:marea")
2. For each dependent node:
   impact = edge_strength × disruption_level × (1 - redundancy)
3. Categorize impact:
   - Critical: impact > 0.8
   - High: impact > 0.5
   - Medium: impact > 0.2
   - Low: impact ≤ 0.2
4. Recurse to depth 3 (prevent infinite loops)

Source: MAREA (US ↔ Spain, 200 Tbps)
Countries Affected: 4
- Spain: Medium (redundancy via other Atlantic cables)
- Portugal: Low (secondary landing)
- France: Low (alternative routes via UK)
- US: Low (high redundancy)
Alternative Routes: TAT-14 (35%), Hibernia (22%), AEConnect (18%)

Source: FLAG Europe-Asia (UK ↔ Japan)
Countries Affected: 7
- India: Medium (major capacity share)
- UAE, Saudi Arabia: Medium (limited alternatives)
- UK, Japan: Low (high redundancy)
Alternative Routes: SEA-ME-WE 6 (11%), 2Africa (8%), Falcon (8%)