Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

Strehlow, K.; Gottsmann, Joachim; Rust, Alison

doi:10.5194/se-6-1207-2015

Cited by 18 publications

(28 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The large simulated water level changes are consistent with observations of large water level fluctuations (<100 m) in wells, increased flow at hot springs, and large influxes of thermal water into drainages as a result of inferred magma intrusion (either within the edifice itself or at greater depth; Matsumoto et al, ; Newhall et al, ; Shibata & Akita, ). Mechanical processes (strain) tend to be invoked to explain changes in water levels (Hurwitz & Johnston, ; Newhall et al, ; Shibata & Akita, ; Strehlow et al, ). Our simulation results are also consistent with previous results that show that edifice permeability structure exerts a significant control on response to hydrothermal perturbations, although the amplitude of water‐table elevation changes in our simulations is smaller than those previously obtained (Hemmings et al ().…”

Section: Discussionmentioning

confidence: 99%

Combining Multiphase Groundwater Flow and Slope Stability Models to Assess Stratovolcano Flank Collapse in the Cascade Range

et al. 2018

View full text Add to dashboard Cite

Hydrothermal alteration can create low‐permeability zones, potentially resulting in elevated pore‐fluid pressures, within a volcanic edifice. Strength reduction by rock alteration and high pore‐fluid pressures have been suggested as a mechanism for edifice flank instability. Here we combine numerical models of multiphase heat transport and groundwater flow with a slope‐stability code that incorporates three‐dimensional distributions of strength and pore‐water pressure to address the following questions: (1) What permeability distributions and contrasts produce elevated pore‐fluid pressures in a stratovolcano? (2) What are the effects of these elevated pressures on flank stability? (3) Finally, what are the effects of magma intrusion on potential flank failure in an edifice? Simulation results show that under a range of plausible parameters, water tables in a stratovolcano can be elevated or perched. These elevated water tables result in universally lower stability (lower factor of safety) compared with equivalent dry edifices, indicating a higher likelihood of flank collapse. Low‐permeability (<1 × 10−17 m2) layers such as altered pyroclastic deposits or breccias can result in locally saturated regions (perched water) and lower factors of safety near the ground surface but may actually reduce liquid water saturation and pore pressures in the core of the edifice and thus may favor small, shallow collapses over larger, deeper collapses. Magma intrusion into the base of the edifice increases pore‐fluid pressures and decreases the factor of safety. However, the shear strength of edifice rocks also exerts a significant control on stability, so both mechanical properties and pore‐fluid pressures are important for stability assessments.

show abstract

Section: Discussionmentioning

confidence: 99%

Combining Multiphase Groundwater Flow and Slope Stability Models to Assess Stratovolcano Flank Collapse in the Cascade Range

et al. 2018

View full text Add to dashboard Cite

show abstract

“…We also simulate the swelling of an heterogeneous porous medium, where we consider that the permeability is zero in the strip 0.45 ≤ x 1 ≤ 0.55 and otherwise we take κ = 1 (that is, five orders of magnitude larger than in the previous test). Zones of zero permeability are commonly encountered in simulation of heterogeneous porous skeletons and layered media [31]. Notice that in classical formulations, the inverse of κ appears in the momentum equation, and thus the problem may degenerate (see [34]).…”

Section: Numerical Testsmentioning

confidence: 99%

Locking-Free Finite Element Methods for Poroelasticity

Oyarzúa

Ruiz–Baier

2016

SIAM J. Numer. Anal.

116

113

View full text Add to dashboard Cite

We propose a new formulation along with a family of finite element schemes for the approximation of the interaction between fluid motion and linear mechanical response of a porous medium, known as Biot's consolidation problem. The steady-state version of the system is recast in terms of displacement, pressure, and volumetric stress, and both continuous and discrete formulations are analyzed as compact perturbations of invertible problems employing a Fredholm argument. In particular, the error estimates are derived independently of the Lamé constants. Numerical results indicate the satisfactory performance and competitive accuracy of the introduced methods.

show abstract

“…Local stress fields can be altered by the intrusion of magma [ Troise , ; Amelung et al , ; Currenti et al , ; Jónsson , ], in turn clamping or unclamping nearby faults [ Roman and Heron , ]. This, in turn, alters the permeability of faults, promoting or inhibiting fluid migration into them [ Hautmann et al , ; Strehlow et al , ]. Distinguishing between magmatic and hydrothermal causes of volcanic unrest, and understanding the role tectonics plays in modulating them, is important for understanding the potential hazard the unrest represents.…”

Section: Introductionmentioning

confidence: 99%

“…Joint inversion of those data yields the absolute density of the source fluid, allowing magmatic versus hydrothermal processes to be distinguished. However, in some cases, gravity and deformation signals are not produced from the same source [e.g., Johnson et al, 2010] and shallow fluid injection may be related to permeability changes induced by deeper magma intrusion [Strehlow et al, 2015]. Interpreting the two as resulting from a single source may mask other processes at work, resulting in an incomplete understanding of the system dynamics.…”

Section: Introductionmentioning

confidence: 99%

Microgravity changes at the Laguna del Maule volcanic field: Magma‐induced stress changes facilitate mass addition

et al. 2017

View full text Add to dashboard Cite

Time‐dependent, or 4‐D, microgravity changes observed at the Laguna del Maule volcanic field, Chile, since 2013, indicate significant (1.5 × 1011 kg) ongoing mass injection. Mass injection is focused along the Troncoso fault, and subparallel structures beneath the lake at 1.5–2 km depth, and is best modeled by a vertical rectangular prism source. The low‐density change (156 to 307 kg/m3) and limited depth extent suggest a mechanism of hydrothermal fluid intrusion into existing voids, or voids created by the substantial uplift, rather than deeper‐sourced dike intrusion of rhyolite or basalt magma. Although the gravity changes are broadly spatially coincident with ongoing surface deformation, existing models that explain the deformation are deeper sourced and cannot explain the gravity changes. To account for this discrepancy and the correspondence in time of the deformation and gravity changes, we explore a coupled magmatectonic interaction mechanism that allows for shallow mass addition, facilitated by deeper magma injection. Computing the strain, and mean, normal, and Coulomb stress changes on northeast trending faults, caused by the opening of a sill at 5 km depth, shows an increase in strain and mean and normal stresses along these faults, coincident with the areas of mass addition. Seismic swarms in mid‐2012 to the west and southwest of the mass intrusion area may be responsible for dynamically increasing permeability on the Troncoso fault, promoting influx of hydrothermal fluids, which in turn causes larger gravity changes in the 2013 to 2014 interval, compared to the subsequent intervals.

show abstract

Poroelastic responses of confined aquifers to subsurface strain and their use for volcano monitoring

Cited by 18 publications

References 34 publications

Combining Multiphase Groundwater Flow and Slope Stability Models to Assess Stratovolcano Flank Collapse in the Cascade Range

Combining Multiphase Groundwater Flow and Slope Stability Models to Assess Stratovolcano Flank Collapse in the Cascade Range

Locking-Free Finite Element Methods for Poroelasticity

Microgravity changes at the Laguna del Maule volcanic field: Magma‐induced stress changes facilitate mass addition

Contact Info

Product

Resources

About