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

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

3. Pico de Tiende

4. Geologic setting

6. N

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

8. Model Geometry 0 1000020000 4000 - 4000 0 (m) PmPm vv khkh seismic shock magma chamber inflation caldera collapse

9. Mohr-Coulomb failure criteria l Young’s modulus l Poisson’s ratio l density of lava/magma l cohesion l internal friction l pore water pressure l normal stress l maximum shear strength E = 7.5x10 3 MPa  = 0.25  l =  m = 2700 kg m -3 c = 0 kPa  =35º P w   max  max = c+(  -P w )tan 

10. Destabilizing volcanic forces

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

12. Numerical modeling

13. Chamber tumescence 0 1000020000 4000 - 4000 0 (m) PmPm vv khkh seismic shock magma chamber inflation caldera collapse P m = 5 MPa

14. Caldera collapse 0 1000020000 4000 - 4000 0 (m) PmPm vv khkh  v = 3 MPa to 30 MPa seismic shock magma chamber inflation caldera collapse

15. Seismicity 0 1000020000 4000 - 4000 0 (m) PmPm vv khkh k h = 0.4 g seismic shock magma chamber inflation caldera collapse

16. Results

17. Distribution of shear stresses

18. Potential yielding zone

19. Influence of seismic acceleration

20. Conclusions

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