NOAA and Understanding Tsunamis

Introduction

• NOAA (National Oceanic and Atmospheric Administration) is a U.S. federal agency focused on climate, weather, oceans, and coasts.
• Acknowledgment of traditional lands and indigenous knowledge.
• Presentation by Nic Arcos from Boulder, Colorado, on tsunamis.

About NOAA and Geophysics

• Nic works for the National Centers for Environmental Information at NOAA.
• Co-located with the World Data Service for Geophysics.
• Geophysics: study of the Earth through indirect methods (e.g., radar, seismic wave measurements).
• Natural hazards group focuses on tsunami data collection, quality control, and access.

Tsunami Data Collection and Analysis

• Global approach to data due to NOAA’s association with World Data Service.
• Key data sources:
  • Eyewitness interviews
  • Scientific catalogs
  • Coastal tide gauges
  • Ocean bottom pressure recorders

Importance of Indigenous Knowledge

• Historical data limitations due to lack of written records in some cultures.
• Indigenous legends and stories are crucial for verifying historical tsunami events.

Tsunami Data and Risk Assessment

• Coastal tide gauges measure sea levels and tsunami waves.
• Ocean bottom pressure recorders detect deep-ocean tsunami waves and transmit data to warning centers.
• Tsunami models help understand potential impacts and risk areas.
• Digital elevation models map Earth's surface to predict tsunami behavior.

Understanding Tsunamis

• Tsunami derived from Japanese "harbor wave."
• Characterized by large waves amplified in enclosed harbors.
• Misnomer: tsunamis are not "tidal waves."
• Tsunamis can travel great distances and affect multiple countries.

Causes and Characteristics of Tsunamis

• Primary causes:
  • Earthquakes (most common)
  • Underwater volcanic eruptions (e.g., Tonga eruption)
  • Landslides
  • Medio tsunamis from fast-moving storms
• Tsunami waves have long wavelengths and travel fast in deep waters.
• As waves approach shore, they slow down and increase in height.

Tsunami Warning and Safety

• NOAA’s Tsunami Warning Centers in Hawaii and Alaska provide alerts.
• Natural warning signs:
  • Ground shaking
  • Roaring ocean sounds
  • Sudden water recession
• Safety measures:
  • Move to higher ground
  • Avoid shorelines during events
  • Follow official "all clear" notices before returning

Tsunami Impact and Historical Events

• Notable historic tsunamis:
  • 2004 Indian Ocean tsunami: 250,000 deaths, affected 15 countries.
  • 2011 Japan tsunami: Over 100 feet height, widespread impact.
• Pacific Ocean, especially the "Ring of Fire," most prone to tsunamis.
• Importance of tsunami evacuation maps and planning.

Audience Q&A

• How far inland to be safe? Depends on location and topography.
• Vertical evacuation options in areas with limited evacuation time.
• Historical data and geological evidence help in planning and risk assessment.

Conclusion

• NOAA's efforts in tsunami research and public safety.
• Encouragement to be aware of tsunami hazards when visiting coastal areas.

Note: These notes summarize key points from Nic Arcos’ presentation on tsunamis, their causes, impacts, and measures for safety and preparedness.