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Large Landslides Triggered by Caldera Collapse Events in Tenerife, Canary Islands

Large Landslides Triggered by Caldera Collapse Events in Tenerife, Canary Islands. by M. Hurlimann, E. Turon and J. Marti. Lanzarote. La Palma. Tenerife. Gran Canaria. Gomera. Fuerteventura. El Hierro. The Canarian Archipelago. Pico de Tiende. Geologic setting. N.

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Large Landslides Triggered by Caldera Collapse Events in Tenerife, Canary Islands

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  1. Large Landslides Triggered by Caldera Collapse Events in Tenerife, Canary Islands by M. Hurlimann, E. Turon and J. Marti

  2. Lanzarote La Palma Tenerife Gran Canaria Gomera Fuerteventura El Hierro The Canarian Archipelago

  3. Pico de Tiende

  4. Geologic setting

  5. N

  6. Incorporated model data • subaerial and subsurface geology and hydrogeology • subaerial and submarine geophysics • remotely sensed data • results of field work • dike trends • vent locations • distribution of pyroclastic deposits

  7. Model Geometry magma chamber inflation seismic shock caldera collapse 4000 0 kh tv Pm (m) - 4000 0 10000 20000 (m)

  8. Young’s modulus Poisson’s ratio density of lava/magma cohesion internal friction pore water pressure normal stress maximum shear strength E = 7.5x103 MPa  = 0.25 l = m = 2700 kg m-3 c = 0 kPa  =35º Pw  max Mohr-Coulomb failure criteria max= c+(-Pw)tan

  9. Destabilizing volcanic forces

  10. Destabilizing volcanic mechanisms 1) chamber tumescence 2) caldera collapse 3) seismicity

  11. Numerical modeling

  12. Chamber tumescence magma chamber inflation seismic shock caldera collapse 4000 0 kh tv Pm (m) - 4000 0 10000 20000 (m) Pm = 5 MPa

  13. Caldera collapse magma chamber inflation seismic shock caldera collapse 4000 0 kh tv Pm (m) - 4000 0 10000 20000 (m) tv = 3 MPa to 30 MPa

  14. Seismicity magma chamber inflation seismic shock caldera collapse 4000 0 kh tv Pm (m) - 4000 0 10000 20000 (m) kh = 0.4 g

  15. Results

  16. Distribution of shear stresses

  17. Potential yielding zone

  18. Influence of seismic acceleration

  19. Conclusions

  20. Conclusions • High shear stresses from tumescence may evolve into the head scarp • Large driving forces following caldera collapse cause destabilization at zones of weakness ~ 100 to 300 m • Ground accelerations greater than 0.3 g may trigger a landslide All 3 processes occurring as one single mechanism would likely cause failure!

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