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Lahar Dynamics and Impact on River Systems

Explore the downstream transformations, effects on communities, and the mobility of lahars post-eruption events like Mt. St. Helens and Mt. Pinatubo through grain size parameters and deposits.

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Lahar Dynamics and Impact on River Systems

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  1. Lahars 13 March 2019

  2. Vallance and Iverson, EOV2, 2015 this is the flow this is the deposit

  3. bulking Downstream transformations of a lahar Vallance and Iverson, EOV2, 2015

  4. Mt. St. Helens – pumiceous pyroclastic flow from 1980

  5. Lahars – effects on river systems and deposits

  6. Lahars at Armero following the eruption of Nevado del Ruiz, 13 November 1985 Mountain front Partial inundation No inundation Total inundation

  7. Lahars filling rivers following the 18 May 1980 eruption of Mount St. Helens

  8. Lahar-inundated communities following the 15 June 1991 eruption of Mt. Pinatubo, Philippines

  9. Breaching of levees by lahars filling river drainages after the Pinatubo eruption

  10. debris flow hyperconc. flow debris flow Above - Debris flow (unstratified) and hyperconcentrated flow (stratified) deposits, east side Mt. Pinatubo Pumice-rich debris flow deposit, east side Mt. Pinatubo, 20-21 Aug 1991 Lake breakout deposits, east side Mt. Pinatubo

  11. Rapid erosion of lahar deposits following the 18 May 1980 Mt. St. Helens eruption

  12. Comparison of air photos taken in June 1978 and June 1980 of the North Fork of the Toutle River near Mt. St. Helens

  13. Maximum inundation levels by lahars following the 18 May 1980 eruption of Mt. St. Helens

  14. Lahar inundations and mud-coated debris after the Mt. St. Helens eruption

  15. Normally graded Osceola Mudflow lahar deposit, Mt. Rainier (Vallance and Scott 1997)

  16. Hummocky Osceola Mudflow deposit, Mt. Rainier (Vallance and Scott 1997)

  17. Mobility of debris avalanches vs. debris flows (from Vallance and Scott 1997) Vallance and Iverson, EOV2, 2015 H = fall height L = runout

  18. Cotopaxi

  19. Chillos Valley lahar, Cotopaxi, Ecuador (Mothes et al 1998) ~4.5 ka, ~3.8 km3 Note the matrix-supported and ungraded lahar deposit

  20. Debris avalanche and lahar dispersal north of Cotopaxi

  21. Comparison of lahar travel distances: Cotopaxi, Mt. St. Helens, Nevado del Ruiz south north

  22. Grain size parameters as a function of distance from the source Chillos Valley lahar Osceola Mudflow

  23. Grain sizes, Chillos Valley lahar

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