Natural Hazards: Mountain Risks

Both ranges generate natural hazards that shape landscapes and human activities. Avalanches pose the most immediate threat, with over 100 fatalities annually across French mountains. Climate change alters avalanche patterns—warmer temperatures create wetter, denser snow that behaves unpredictably. Avalanche protection structures—barriers, nets, and forests—represent massive investments in mountain safety.

Rockfall and landslides increase as permafrost thaws and intense precipitation events become more common. The 1248 collapse of Mont Granier, which buried 16 villages, reminds us of catastrophic potential. Modern monitoring systems track unstable slopes, but risks increase as climate change destabilizes previously frozen rock faces.

Floods and debris flows punctuate mountain history. Glacier lake outburst floods threaten some valleys as retreating glaciers leave unstable moraine dams. Flash floods in Mediterranean-influenced areas can transform dry streambeds into torrents within minutes. The 1996 Biescas tragedy in the Spanish Pyrenees, which killed 87 people, demonstrates the deadly potential of mountain floods.

Seismic activity, while generally moderate, occasionally produces damaging earthquakes. The Alps experience regular minor tremors as compression continues. The Pyrenees show more significant seismic risk, with several magnitude 5+ earthquakes recorded historically. The 1967 Arette earthquake destroyed villages and altered building codes throughout the range.