large landslides triggered by caldera collapse events in tenerife, canary islands by m. hurlimann,...
Post on 21-Dec-2015
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Large Landslides Triggered by Caldera Collapse
Events in Tenerife, Canary Islands
by M. Hurlimann, E. Turon and J. Marti
Incorporated model dataIncorporated 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
Model Geometry
0 10000 20000
4000
- 4000
0
(m)
(m)
Pmvkh
seismicshock
magmachamberinflation
calderacollapse
Mohr-Coulomb failure criteria
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
max= c+(-Pw)tan
Chamber tumescence
0 10000 20000
4000
- 4000
0
(m)
(m)
Pmvkh
seismicshock
magmachamberinflation
calderacollapse
PPm m = 5 MPa= 5 MPa
Caldera collapse
0 10000 20000
4000
- 4000
0
(m)
(m)
Pmvkh
v v = 3 MPa to 30 MPa= 3 MPa to 30 MPa
seismicshock
magmachamberinflation
calderacollapse
Seismicity
0 10000 20000
4000
- 4000
0
(m)
(m)
Pmvkh
kkh h = 0.4 g= 0.4 g
seismicshock
magmachamberinflation
calderacollapse
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!