scholarly journals Correction to “Pore pressure and poroelasticity effects in Coulomb stress analysis of earthquake interactions” by Massimo Cocco and James R. Rice

2003 ◽  
Vol 108 (B2) ◽  
Author(s):  
M. Cocco ◽  
J. R. Rice
Keyword(s):  
Stress Analysis ◽  
Pore Pressure ◽  
Coulomb Stress ◽  
Coulomb Stress Analysis

scholarly journals Coulomb stress analysis for several filling and operational scenarios at the Grand Ethiopian Renaissance Dam impoundment

2021 ◽  
Vol 80 (7) ◽  
Author(s):  
Austin Madson ◽  
Yongwei Sheng
Keyword(s):  
Coulomb Stress ◽  
Engineering Structures ◽  
Main Driver ◽  
Potential Reservoir ◽  
Coulomb Stress Analysis ◽  
Storage Change ◽  
Total Maximum ◽  
Western Ethiopia ◽  
Maximum Stresses

AbstractIncreased demand for power generation coupled with changing seasonal water uncertainty has caused a worldwide increase in the construction of large hydrologic engineering structures. That said, the soon-to-be-completed Grand Ethiopian Renaissance Dam (GERD) will impound the Blue Nile River in Western Ethiopia and its reservoir will encompass ~ 1763 km2 and store ~ 67 Gt (km3) of surface water. The impoundment will undergo maximum seasonal load changes of ~ 28 to ~ 36 Gt during projected seasonal hydroelectric operations. The GERD impoundment will cause significant subsurficial stresses, and could possibly trigger seismicity in the region. This study examines Coulomb stress and hydrologic load centroid movements for several GERD impoundment and operational scenarios. The maximum subsurficial Coulomb stress applied on optimally oriented fault planes from the full impoundment is ~ 186 kPa and over 30% of our model domain incurs Coulomb stresses ≥ 10 kPa, regardless of the impoundment period length. The main driver behind Coulomb stress and load centroid motion during impoundment is the annual, accumulated daily reservoir storage change. The maximum Coulomb stresses from the highest amplitude season of five long-term operational scenarios are around 36, 33, 29, 41, and 24% of the total maximum stresses from the entire GERD impoundment. Variations in annual Coulomb stresses during modeled GERD operations are attributed to the seasonal load per unit area, and partially to the initial seasonal water level. The spatial patterns and amplitudes of these stress tensors are closely linked to both the size and timing of GERD inflow/outflow rates, and an improved understanding of the magnitude and extent of these stresses provides useful information to water managers to better understand potential reservoir triggered seismic events from several different operational and impoundment strategies.

scholarly journals Slip distribution effect in spatial coulomb stress analysis (Case study: Palu earthquake on September 28, 2018)

2021 ◽  
Vol 873 (1) ◽  
pp. 012033
Author(s):  
Kevin Hanyu Clinton Wulur ◽  
Iman Suardi ◽  
Sesar Prabu Dwi Sriyanto ◽  
Yusuf Hadi Perdana
Keyword(s):  
Fault Plane ◽  
Body Wave ◽  
Slip Distribution ◽  
Inversion Method ◽  
Coulomb Stress ◽  
The North ◽  
Wave Inversion ◽  
Dip Angle ◽  
Coulomb Stress Analysis

Abstract On September 28, 2018, the Palu-Koro fault released the accumulated stress that caused the earthquake. An earthquake with magnitude 7.5 caused large and massive damage around Palu. There were many aftershocks along the Palu-Koro fault. This research aims to calculate a model of spatial Coulomb stress based on this event to find a correlation between mainshock and the aftershocks. The slip distribution was used as an input of the spatial stress Coulomb modeling to increase the accuracy. We use the Teleseismic Body-Wave Inversion method to calculate slip distribution along the fault plane. As a result, this earthquake was generated by the Palu-Koro fault movement with Mw 7.48, strike 350°, dip angle 67°, and rake -9°. There are three asperity zones along the fault plane located in the north and southern parts of the fault plane. The location of the most energy discharge is in the south asperity zone of the fault plane model with a maximum slip value of 1.65 meters. The spatial Coulomb stress change of this event shows that aftershocks concentration are in areas experiencing increased stress after the earthquake.

2D finite-element modelling of the interaction between poroelastic effects and viscoelastic relaxation during the seismic cycle

2021 ◽  
Author(s):  
Jill Peikert ◽  
Andrea Hampel ◽  
Meike Bagge
Keyword(s):  
Pore Pressure ◽  
Lower Crust ◽  
Fluid Pressure ◽  
Coulomb Stress ◽  
Viscoelastic Relaxation ◽  
Pore Fluid Pressure ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Stress Changes ◽  
Pressure Changes

<p>The analysis of the Coulomb stress changes has become an important tool for seismic hazard evaluation because such stress changes may trigger or delay next earthquakes. Processes that can cause significant Coulomb stress changes include coseismic slip, earthquake-induced poroelastic effects as well as transient postseismic processes such as viscoelastic relaxation. In this study, we investigate the spatial and temporal evolution of pore fluid pressure changes and fluid flow during the seismic cycle, their dependency on the permeability in the crust and the interaction with postseismic viscoelastic relaxation. To achieve this, we use 2D finite-element models for intra-continental normal and thrust faults, which include coseismic slip, poroelastic effects, postseismic viscoelastic relaxation and interseismic stress accumulation. In different experiments, we vary (1) the permeability of the upper and lower crust while keeping the viscosity structure constant and (2) the viscosity of the lower crust and lithospheric mantle, while we keep the permeabilities constant. (1) The modelling results show that the highest changes in pore fluid pressure during and after the earthquake occur within a distance of ~ 1 km around the lower fault tip at the transition between upper and lower crust. The evolution of pore pressure and fluid flow depends primarily on the permeability in the upper crust. With decreasing permeability, the possibility of the pore fluids to flow decreases and thus, in the postseismic phase, the duration of the poroelastic relaxation increases, from a few days to several years, until the pore pressure reaches the initial pressure of the preseismic phase. In contrast, the influence of variations of the permeability in the lower crust on the pore pressure changes is negligible. For high upper-crustal permeabilities, postseismic vertical velocities are high and decreases rapidly with time, from around 120 mm/a after the first year by two orders of magnitude after 10 years, whereas for low permeabilities they remain consistently low over the years after the earthquake. (2) Models with low viscosity of the lower crust show that the timescales of poroelastic effects and viscoelastic relaxation overlap and affect the postseismic velocity already in the early postseismic phase and that both processes decay within a few years after the earthquake. For higher viscosities, the velocity is initially dominated by pore pressure changes during the first few years, whereas viscoelastic relaxation lasts for decades. Both processes also show differences in their spatial scale. Poroelastic effects occur within a few kilometers around the fault, whereas viscoelastic relaxation acts on tens to hundreds of kilometers. As both processes can cause Coulomb stress changes on faults in the vicinity of the earthquake source fault, it is important to understand the spatial and temporal evolution, the effects on the individual faults and the interaction of both processes during the earthquake cycle. Future work will therefore include the calculation and examination of Coulomb stress changes on intra-continental normal and thrust faults using 3D models that include poroelastic effects and viscoelastic relaxation.</p>

scholarly journals Petroleum geomechanics modelling in the Eastern Mediterranean basin: analysis and application of fault stress mechanics

2018 ◽  
Vol 73 ◽  
pp. 57 ◽  
Author(s):  
Nikolaos Markou ◽  
Panos Papanastasiou
Keyword(s):  
Stress Analysis ◽  
Pore Pressure ◽  
Shear Failure ◽  
Eastern Mediterranean ◽  
Prediction Method ◽  
Earth Model ◽  
Gas Field ◽  
Wide Range ◽  
The Stability

A fault stress analysis of a typical gas field in the Eastern Mediterranean is presented. The objective of this study is to provide estimates of thein situstresses and pore pressure for populating a regional Mechanical Earth Model and to characterize the stability of faults under current and changing reservoir conditions. The fault stability analysis is based on the Mohr-Coulomb frictional faulting theory. The verticalin situstress is estimated using seismic and density data and the bounds of the horizontal stresses were determined for different fault regimes. The pore pressure for determining the effectivein situstresses is estimated using the Bowers pore pressure prediction method. Fault stress analysis is performed in a series of calculations and the results are plotted on Mohr diagrams for shear failure. The fault stress analysis is performed on a wide range of alternative azimuth orientations forSHmaxin order to capture the uncertainty on the actual orientation. Sensitivity with respect to reservoir pore pressure change suggests that pressure reduction in the reservoir improves the fault stress stability, ignoring in the current analysis any stress arching effects. Pore pressure increase decreases the normal stress on the fault leading to increasing risk of shear failure of the critically stressed faults. The case study examines eight faults on the Aphrodite gas field with the objective to characterize if the faults are active or remain dormant under current stress conditions and how the stability may change in reservoir injection or depletion conditions.

Effective-Stress Finite Element Analysis of Spudcan Penetration

2012 ◽  
Author(s):  
Jiang Tao Yi ◽  
Fook Hou Lee ◽  
Siang Huat Goh ◽  
Yu Ping Li ◽  
Xi Ying Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Pore Pressure ◽  
Effective Stress ◽  
Excess Pore Pressure ◽  
Element Analysis ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Excess Pore

The numerical modeling of spudcan penetration involves technical challenges posed by large soil deformation coupled with significant material non-linearity. The Lagrangian approach commonly used for solid stress analysis often does not work well with large deformations, resulting in premature termination of the analysis. Recently, the Arbitrary Langrangian Eulerian (ALE) and the Eulerian methods have been used in spudcan analysis to overcome problems caused by the soil flow and large deformation. However, most of the reported studies are based on total stress analysis and therefore shed no light on the excess pore pressures generated during spudcan installation. As a result, much remains unknown about the long-term behaviour of spudcans in the ground, which is affected by the dissipation of excess pore pressures. This paper reports an effective-stress finite element analysis of spudcan installation in an over-consolidated (OC) soft clay. The Eulerian analysis was conducted using ABAQUS/ Explicit, with the effective stress constitutive models coded via the material subroutine VUMAT. The results demonstrated the feasibility of conducting effective-stress finite element analysis for undrained spudcan penetration in OC clays. The paper discusses the flow mechanism, stable cavity depths and bearing capacity factors when spudcan installation occurs in various OC soils. It was found that the pore pressure build-up concentrates in a bulb-shaped zone surrounding the spudcan. The size of the pore pressure bulb increases with increasing penetration. The maximum excess pore pressure, which is generated near the spudcan tip, is predominantly controlled by the undrained shear strength at the tip level.

Sign in / Sign up

Export Citation Format

Share Document