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Using Tsunami Deposits to Determine Earthquake and Tsunami Recurrence Intervals: Opportunities and Challenges

This study explores the use of historic and pre-historic tsunami deposits to document tsunami hazard, produce probabilistic hazard maps, calculate recurrence intervals, understand tsunami behavior, and enhance tsunami runup modeling.

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Using Tsunami Deposits to Determine Earthquake and Tsunami Recurrence Intervals: Opportunities and Challenges

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  1. Using tsunami deposits todetermine earthquake and tsunami recurrence intervals: opportunities and challenges Jody Bourgeois Earth & Space Sciences University of Washington Seattle, Washington Soldatskaia Bay Kamchatskii Peninsula

  2. We can use (historic and pre-historic) • deposits from tsunamis to: • Document tsunami hazard where unknown historically • and where prehistoric tsunamis are larger • Help produce probabilistic hazard maps • Calculate tsunami recurrence intervals • (typically centuries long) • Understand tsunami behavior • Calibrate, test and enhance tsunami runup modeling • Educate the public

  3. We can use (historic and pre-historic) • deposits from tsunamis to: • Document tsunami hazard where unknown historically • and where prehistoric tsunamis are larger • Help produce probabilistic hazard maps • Calculate tsunami recurrence intervals • (typically centuries long) • Understand tsunami behavior • Calibrate, test and enhance tsunami runup modeling • Educate the public

  4. intro QUESTIONS: WHERE? HOW BIG? HOW OFTEN?

  5. intro QUESTIONS: WHERE? HOW BIG? HOW OFTEN? Problem: Historic records are short and tsunami recurrence intervals are long.

  6. Oldest catalogued tsunami*: Mediterranean 4th c. B.C. Japan 7th century China, Central & South America 16th century Philippines, Indonesia 17th century Russian Far East & Alaska 18th century North America, New Zealand 19th century *classified as definite Lander and Gusiakov, 1997 and online catalogues

  7. How can geology help tell our (hi)story?

  8. Copalis deposit mudflat deposits in years after tsunami tsunami deposit grassy field c. 300 years ago Copalis River bank, Washington State coast

  9. Coring at Willapa Bay for the longer tsunami record MaryAnn coring

  10. This and other cores tell us that large earthquakes and tsunamis occur on the Washington coast every 100-1000 years (average ~500 years) There are similar records for all of Cascadia and also the Gulf of Alaska Willapa longer record ~300 years ago Atwater, Carver, Clague, Darienzo, Gilpin, Hemphill-Haley, Hutchinson, Kelsey, Nelson, Peterson, Williams, Witter,… Turbidites: Goldfinger, Karlin ~3500 years ago

  11. n. Japan-Kuril-Kamchatka subduction zone history (compiled by Brian Atwater) Hokkaido

  12. n. Japan-Kuril-Kamchatka subduction zone history Hokkaido Tsunami deposits take the record back thousands of years

  13. pre-20th centurytsunami depositsfound farther inland Nanayama, Atwater, Satake and several others

  14. n. Japan-Kuril-Kamchatka subduction zone history Kamchatka

  15. FIELD METHODS profiles excavations tsunami deposits tephra stratigraphy marine terraces

  16. Polar w/o ice K-centric

  17. Polar w/o ice K-centric

  18. Polar w/o ice K-centric

  19. Hungry America “hungry America” model (USGS website)

  20. Polar with plate boundaries after Fujita Mackey & others NAM EUR BER OKH PAC

  21. Polar with plate boundaries OKH

  22. Polar with plate boundaries BER

  23. Three backpackers How many and what kinds of plate boundaries? How does Kamchatka coastal neotectonics elucidate this problem?

  24. Cloudy Kamchatka

  25. LARGE Polar with plate boundaries NAM EUR NAM NAM PAC

  26. LARGE Polar with plate boundaries NAM EUR BER OKH PAC

  27. uplifted marine terraces uplift rates mm/yr (m/kyr) for last 500k years

  28. KAMCHATKA LAND Mw 7.7 tsunamigenic earthquake

  29. 1969Ozernoitsunamimodel (Titov)(snapshots) one possible source configuration

  30. KAMCHATKA LAND Mw 7.7 tsunamigenic earthquake

  31. Stolbovaya field site peat & tephra Bering Sea coast bumpy tundra

  32. Stolbovaya siteProfile 1, trench 104 1969 Ozernoi tsunami deposit -> 1964 Shiveluch volcanic ash -> paleo-tsunami deposit -> Shiveluch c. 1650 A.D. -> paleo-tsunami deposit -> Ksudach caldera c. 250 A.D. ->

  33. one of 14 profiles at Stolbovaya total of >50 excavations

  34. Tsunami frequencyper 1000 years

  35. Tsunami frequencyper 1000 years Stolbovaya recurrence rate ~1/2 KSZ &greater than many other subduction zones

  36. Mw 7.7 Ozernoi modeled by 1969 Ozernoi tsunami data and deposits indicates c. 3 m horizontal shortening Recurrence intervals for such tsunamis (from deposits) indicates shortening of c. 15 mm/yr over last 4000 yr

  37. Hungry America “hungry America” model

  38. LARGE Polar with plate boundaries Fujita, Mackey and others NAM EUR BER OKH PAC

  39. Challenges Geochronology Correlation Statistics

  40. Challenges Geochronology Correlation Statistics How many observations are sufficient? What is the preservation factor? (Signor-Lipps)

  41. Challenges Going beyond tsunami recurrence to earthquake recurrence

  42. Challenges Going beyond tsunami recurrence to earthquake recurrence and onward to paleotsunami and earthquake magnitudes

  43. Challenges Paleogeography Paleobathymetry Paleotopography and onward to paleotsunami and earthquake magnitudes

  44. Applications Paleoseismology Neotectonics Archaeology Coastal geomorphology Seismic & tsunami hazards Education & outreach

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