Understanding Landslides and the Oso Disaster

Overview

• Landslides: Common natural disasters involving the movement of rock, soil, and debris due to gravity. Can happen anytime, anywhere.

Key Figures

• David Montgomery: Geologist at University of Washington, funded by NSF. Studies past and present landslides.
• Geotechnical Extreme Event Reconnaissance Team: Group investigating the Oso disaster, includes Montgomery.

The 2014 Oso Landslide

• Date: March 22, 2014, near Oso, Washington
• Impact: 18 million tons of mud and debris
  • Destroyed 40+ homes and structures
  • Engulfed almost a mile of highway
  • 43 fatalities
  • Millions in property damage
• Initial Questions: Why did the hillside fail?

Investigative Methods

• Geomorphology: Study of Earth's surface evolution
• Data Collection: Post-disaster documentation to preserve data
• Causes: Excessive rain or earthquakes displacing material
  • Forms slurry (semi-liquid material)
  • Can reach speeds up to 100 mph
• Types of Landslides: Deep (large sections of mountains) and shallow (surface soil)

Analytical Tools

• Aerial Photography & LIDAR: Used to create 3D terrain maps
  • Historical analysis showed previous landslides (pre-2006, even older)
• Computer Modeling: Digital representation under different conditions (e.g., heavy rainfall)
  • Slope stability models to predict high-risk areas

Field Studies

• Carbon Glacier, Mount Rainier: Recent landslides and debris flows
  • Melting glacier increases sediment flow
  • Damage to surrounding environment
• Importance: Field data needed for understanding and predicting landslides

Lessons and Future Work

• Frequency Analysis: Understanding how often landslides occur
• LIDAR Limitations: Requires focused geological study

Conclusion

• Significance: While landslides can't be fully prevented, research helps understand their causes and effects.