1. Strengthening Tsunami Warning and Emergency Response Suva, Fiji 24 September 2010 Tsunami Science and Hazard Assessment Laura Kong Director, International Tsunami Information Center Stuart Weinstein Deputy Director, Pacific Tsunami Warning Center

2. UNESCO/IOC-NOAA International Tsunami Information Center Enabling Learning Objectives 2-1 Explain what a tsunami is (generation, wave characteristics, occurrence) 2-2 Explain differences between local and distant tsunamis 2-3 Discuss what scientists learn from historic records (written accounts, data observations) 2-4 Discuss the importance of indigenous knowledge in tsunami preparedness 2-5 Learn the purpose, scope, and goals of tsunami numerical modeling

3. UNESCO/IOC-NOAA International Tsunami Information Center What is a tsunami? Japanese for “harbor wave” No connection with tides. Not tidal wave. Series of waves for hours. 1 st wave may not be largest. 40 cm, 1.5 hr later, 4 th wave arrival F. Gonzalez, NOAA, Tsunami! In Scientific American, 1999

4. UNESCO/IOC-NOAA International Tsunami Information Center What is a tsunami? Wavelength long (20 to 100s km), so cannot see next wave. Grows in height at coast. Few cm in deep ocean. Can grow to 10s of meters at coast. Travels fast in deep ocean (jet airplane), but slows down at coast (but cannot outrun). 220m/s 800km/hr 10m/s 36km/hr 30m/s 110km/hr 70m/s 250km/hr

5. UNESCO/IOC-NOAA International Tsunami Information Center What is a tsunami? Wave frequency every 5-60 minutes. TYPE CAUSE TIME / CYCLE SEA & SWELL WIND 2 - 25 SEC TSUNAMIS RAPID OCEAN 5 - 60 MIN DISPLACEMENT TIDES ASTRONOMICAL > 12 HRS CYCLES

6. UNESCO/IOC-NOAA International Tsunami Information Center What does a tsunami look like? Rapidly rising/falling sea level Wall of water (not breaking surf wave) Receding wave (seafloor exposed) Fast flowing, debris-laden river

7. UNESCO/IOC-NOAA International Tsunami Information Center What does a tsunami look like? Indonesia, Dec 26, 2004 Thailand Video Indonesia Video Indian Ocean Tsunami, December 26, 2004 Asian Tsunami: Disaster of the Century, Asia-Pacific Broadcasting Union, 2006

8. UNESCO/IOC-NOAA International Tsunami Information Center What does a tsunami do? Objects become battering rams Erode, scour, deposit mud ⇒ Death, debris ⇒ Structures/utilities collapse ⇒ Fire, HAZMAT American Samoa, R. Madsen, G. Yamasaki, 2009 Concepcion, Chile, L. Kong, 2010

9. UNESCO/IOC-NOAA International Tsunami Information Center Digital Globe Banda Aceh, Indonesia Dec 26, 2004 Pago Pago, American Samoa Sept 29, 2009 John Pughnat What does a tsunami do? Before After Largest wave draining Quickly inundates low-lying areas Flooding, strong currents Before After

10. UNESCO/IOC-NOAA International Tsunami Information Center How often do tsunamis occur? 1900-2009: ~1 fatal tsunami/year

11. UNESCO/IOC-NOAA International Tsunami Information Center Where do tsunamis occur? Fewer are distant tsunamis Most are local/regional tsunamis All tsunamis UNESCO/IOC Tsunami Glossary 2008

12. UNESCO/IOC-NOAA International Tsunami Information Center How are tsunamis generated? Earthquakes (most common) Underwater or sub-aerial landslides (less common) Volcanic eruptions (infrequently) Meteor impact (rarely) Subduction Zone Tsunami G. Fryer, Pacific Tsunami Warning Center

13. UNESCO/IOC-NOAA International Tsunami Information Center How fast? Local tsunamis Source is near community Waves arrive within minutes In earthquake-generated tsunami, likely occurrences prior to wave arrival onto land: –Strong ground shaking resulting in building damage –Rapid sea level changes –Land level changes (rupture, subsidence, uplift)

14. UNESCO/IOC-NOAA International Tsunami Information Center How fast? Distant tsunamis Source far from community (1000s km away) Waves arrive in hours “Ring of Fire” subduction zones can generate distant tsunamis Tsunami can have local AND distant impacts –Chile Subduction Zone (local in Chile; distant in Hawaii, Tonga

15. UNESCO/IOC-NOAA International Tsunami Information Center How fast? Distant tsunamis B. Atwater, Surviving a tsunami—lessons from Chile, Hawaii, and Japan US Geol. Surv. Circ., 1187, 1999

16. UNESCO/IOC-NOAA International Tsunami Information Center Assessing the Tsunami Hazard: Looking Back in Time Historic records, written eyewitness accounts & event data observations - such as wave height, flooding extent, summary impact, etc… Indigenous knowledge

17. UNESCO/IOC-NOAA International Tsunami Information Center Historic Records Written summaries include reports, diaries, logs, newspaper, etc… Tsunami databases summarize tsunami events, observations World Data Center for Tsunamis (NGDC) TsuDig GIS database, NGDC-ITIC

18. UNESCO/IOC-NOAA International Tsunami Information Center Geologic Record – Paleotsunamis On most coasts, multiple lifetimes elapse between big tsunamis. If discovered, natural records of sand deposits provide clues to estimate future recurrence interval of big tsunamis. USGS

19. UNESCO/IOC-NOAA International Tsunami Information Center Indigenous Knowledge - Folklore and Oral Traditions Stories, songs, and legends handed down through generations complement existing modern hazard assessment tools Local wisdom and past experiences support education “Thunderbird and Whale”

20. What is likelihood of occurrence? Historical and Future Hazard What is expected tsunami impact at coast? Numerical modeling => Source, tsunami => Inundation Tsunami Risk Assessment F. Gonzalez, NOAA, Tsunami! In Scientific American, 1999

21. UNESCO/IOC-NOAA International Tsunami Information Center Tsunami Modeling – Why? Historical tsunamis allow scientists to understand how tsunamis behave Tsunamis are high impact, but infrequent Modeling scenarios essential –Simulate: When tsunami will hit coast? Where highest? How far floods inland? Where strong currents are? Result 1: Inundation map of ALL credible scenarios Result 2: Community uses for evacuation planning

22. UNESCO/IOC-NOAA International Tsunami Information Center Modeling to Evacuation Map Max Inundation + Currents Evacuation map Long Beach, Washington (NOAA, WA EMD)

23. UNESCO/IOC-NOAA International Tsunami Information Center Summary Explained and showed what a tsunami is Explained differences between local and distant tsunamis Described types of historic records used for hazard assessment (written, data observations) Described how indigenous knowledge helps hazard assessment and tsunami preparedness Learned why tsunami numerical modeling is used for community preparedness

24. Strengthening Tsunami Warning and Emergency Response Suva, Fiji 24 September 2010 Thank you