Post-Seismic Viscoelastic Deformation And Stress

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The calculation of these stress changes has become an important tool for seismic hazard evaluation, but the combined influence of coseismic slip, interseismic stress accumulation and transient postseismic processes including poroelastic effects and viscoelastic relaxation on the velocity and stress field in the crust has not been systematically

The abovementioned postseismic studies associated with the Gorkha earthquake concentrated on early afterslip, without taking viscoelastic deformation into consideration, which makes the dominant contribution to the mid-far-field deformation during the mid-long-term postseismic phase.

regional tectonic deforma-tion (B ̈urgmann & Dresen 2008 ). The post-seismic deformation recorded by geodeticobservations is partially due to the viscoelas-tic relaxation of the deep ductile layer under the perturbations of the coseismic stress, and has been used to constrain the rheolog- ical properties andbehavioursin areas surrounding the In order to reveal the stress-triggering mechanism of the 2022 Menyuan earthquake and quantitatively analyze the stress evolution of the Haiyuan Fault Zone over the century, we comprehensively consider the influence of co-seismic, post-seismic and inter-seismic effects of the earthquake cycle. Viscoelastic relaxation caused by the coseismic slip makes an important contribution to the postseismic deformation and is crucial for evaluating the regional rheology, stress transfer over the long-term, and for evaluating the impact of an earthquake on further seismic potential (Tian et al., 2020; Tang et al., 2023; Zhao et al., 2017).

pyrocko/fomosto-psgrn-pscmp

The truth lies in between, and determining TA and the importance of afterslip relative to viscoelastic relaxation in controlling short-term post

These post-seismic observations were previously explained by post-seismic afterslip on the downdip extension of the 1960 rupture plane. In this study, we demonstrate that the post-seismic observations can be explained alternatively by volumetric viscoelastic relaxation of the asthenosphere mantle. Abstract and Figures The objective of this study was to examine co- and post-seismic deformation following the 2011 Mw9.0 Tohoku-Oki earthquake and its impact on Northeast Asia. Post-seismic viscoelastic deformation and stress transfer after the 1960M9.5 Valdivia, Chile earthquake: effects on the 2010M8.8 Maule, Chile earthquake Min Ding1and Jian Lin2,3

After the 1960 M9.5 Valdivia, Chile earthquake, three types of geodetic observations were made during four time periods at nearby locations. These post-seismic observations were previously explained by post-seismic afterslip on the downdip extension of the 1960 rupture plane. In this study, we demonstrate that the post-seismic observations can be explained alternatively by References (52) Abstract This chapter deals with the mechanism of stress relaxation due to the viscous flow after the occurrence of an earthquake, leading to post-seismic deformation. FORTRAN code for calculating of co- and post-seismic deformation in multi-layered viscoelastic half-space based on the viscoelastic-gravitational

These so-called post-seismic deformations include contributions mainly from afterslip and viscoelastic relaxation, quantification of their relative influence is of importance for understanding the evolution of post-seismic crustal stress, strain and aftershocks.

Investigations of the co- and postseismic processes of the 2011 Tohoku-oki earthquake provide essential information on the seismic cycle in the Japan Trench. Although almost all of the source region lies beneath the seafloor, recent seafloor geophysical instruments have enabled to detect the near-field signals of both the coseismic rupture and the postseismic Sketch of inelastic properties of the lithosphere responsible for post-seismic transients. Post-seismic deformation may be due to a combination of poroelastic response, fault creep and viscous shear. The shear flow in the mantle and lower crust might be governed by a power-law viscosity for high stress and by a Newtonian viscosity at lower stress. In the former

Models incorporating viscous shear zones give more stationary interseismic deformation than layered half-space, Maxwell viscoelastic models

Postseismic deformation due to the 2021

Postseismic deformation following large earthquakes has been routinely observed and explained as the response of the lithosphere to coseismic stress redistribution (Bürgmann and Dresen, 2008). The main mechanisms proposed for postseismic deformation include viscoelastic relaxation of coseismically induced stress changes in the ductile lower crust and The occurrence of faulting in the lithosphere is responsible for an instantaneous deformation of the Earth’s surface, which is called co-seismic deformation. In response to the induced elastic stress in the mantle, creep occurs in this deep portion of the planet, or in the ductile portion of the crust, via viscoelastic stress relaxation. Immediately after the occurrence of the earthquake

1 Introduction Following a great megathrust earthquake, continuing slip (afterslip) or relocking of different parts of the subduction fault and relaxation of coseismicially induced stresses in the viscoelastic mantle (viscoelastic relaxation) continue to drive crustal deformation [Wang et al., 2012]. Properly assessing these processes helps us understand fault mechanics Post-seismic viscoelastic deformation and stress transfer after the 1960 M9.5 Valdivia, Chile earthquake: Effects on the 2010 M8.8 Maule, Chile earthquake Similarly, postseismic viscoelastic relaxation represents lower-crustal and upper-mantle responses to stress perturbation of earthquakes, supplying information about lithospheric rheology and strength (Bürgmann and Dresen, 2008; Wang and Barbot, 2023).

This zone is also a region of anomalously low seismicity and low Vp/Vs ratio [Kim et al., 2005; Wu et al., 2007]. The Chi-Chi earthquake induced co-seismic stress changes of the order of a few MPa in that zone of presumably low viscosity (Figure 3), which might therefore have experienced detectable viscoelastic relaxation.

Our findings suggest that the slip on the fault and stress relaxation at depth jointly control the deformation pattern. Notably, the stress relaxation at depth has a significant impact on the assessment of deep slip. The shallow slip may be related to aftershocks. These findings demonstrate that neglecting centennial postseismic deformation introduces systematic biases in fault parameter estimation. Our study advances understanding of long-term viscoelastic processes and provides critical constraints for seismic hazard assessment in intracontinental strike-slip systems. Megathrust earthquakes impose changes of differential stress and pore pressure in the lithosphere-asthenosphere system that are transiently relaxed during the postseismic period primarily due to afterslip, viscoelastic and poroelastic processes. Especially during the early postseismic phase, however, the relative contribution of these processes to the observed

Geophysical Journal International

Wang, R., F. Lorenzo-Martin and F. Roth (2006), PSGRN/PSCMP – a new code for calculating co- and post-seismic deformation, geoid and gravity changes based on the viscoelastic-gravitational dislocation theory, Computers and Geosciences, 32, 527-541. Exploring the deformation mechanism of the 2021 Mw 7.4 Maduo Earthquake is crucial for better understanding the seismic hazard of the faults with low strain rates inside the Bayan Har block. This study leverages deformation information derived from Sentient-1 A/B images and GPS data to investigate in detail the co- and postseismic deformation mechanisms Here, we construct a 3D viscoelastic finite element model to calculate crustal stress evolution on the Kunlun fault, especially the two seismic gaps. The effects of far-field tectonic loading, inter-seismic fault creep in ductile shear

The analysis of Coulomb stress changes has become an important tool for seismic hazard evaluation because such stress changes may trigger or delay subsequent earthquakes. Processes that can cause significant Coulomb stress changes include coseismic slip and transient postseismic processes such as poroelastic effects and viscoelastic relaxation. Two aseismic deformation processes are commonly invoked to explain the transient geodetic surface displacements that follow a major earthquake: afterslip and viscoelastic relaxation. Both induce time dependent stress variations in the crust, potentially affecting aftershock occurrence. However, the two mechanisms‘ relative impacts on crustal deformation

The contribution of stress-driven af-terslip andviscoelastic relaxationmechanismsin the post-seismic deformation of thePishanearthquake wascalculated by theproce-dures introducedin Diao et al. ( 2021 ). Large subduction earthquakes induce complex postseismic deformation, primarily driven by afterslip and viscoelastic relaxation, in addition to interplate relocking processes. However, these

Postseismic LOS deformation displayed logarithmic behavior, and the temporal evolution of the post-seismic deformation is consistent with the aftershock sequence. The early postseismic deformation measured with Sentinel-1 interferometry is therefore indicative of afterslip reaching to the Earth’s surface, suggesting that at least part of the shallow coseismic slip deficit inferred for the Maduo earthquake (Figures 3 and 4) is due to the velocity-strengthening conditions above the seismogenic

Post-seismic deformation, representing the surface strain history in response to lithospheric stress perturbations, provides important insights into the lithospheric rheology and active structures. Here, we construct a new 3-D post-seismic deformation model for the Wenchuan earthquake, invoking viscoelastic relaxation and afterslip. PURPOSE: RELAX computes nonlinear time-dependent viscoelastic deformation with powerlaw rheology and rate-strengthening friction in a cubic grid due to coseismic stress changes, initial stress, surface loads, and/or moving faults.

We emphasize the role of the transient rheology extending to large depths in the upper mantle in controlling the deformation. We also study the role of the elastic plate serving as a stress guide against asthenospheric resistance in the postseismic deformation and the resultant parameter scaling relationships. SUMMARY Satellite-derived gravity data offer a novel perspective for understanding the physics of megathrust earthquakes at subduction zones. Nonetheless, their temporal resolution and observational errors make it difficult to discern the different phases of the seismic cycle, as the elastostatic deformation (coseismic) and the stress relaxation by viscous

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