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Mark Simons - One of the best experts on this subject based on the ideXlab platform.
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Accounting for uncertain Fault Geometry in earthquake source inversions – II: application to the Mw 6.2 Amatrice earthquake, central Italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 Mw 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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accounting for uncertain Fault Geometry in earthquake source inversions ii application to the mw 6 2 amatrice earthquake central italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 M_w 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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Accounting for uncertain Fault Geometry in earthquake source inversion
2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Inferences of the history of Fault slip are subject to biases induced by unavoidable imperfections in the assumed forward model. For example, we commonly simplify assumed model of crustal properties and the Geometry of the Fault. The impacts of these choices are rarely investigated or quantified. Here, we explore the impact of uncertainties related to the choice of a Fault Geometry. To do so, we develop an augmented misfit covariance matrix which approximates the uncertainty related to the choice of a given Fault Geometry, following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We validate this approach with the simplified case of a Fault that extends infinitely along strike, investigating the impact of uncertainty in Fault dip and location. We apply our methodology to the 2016 Mw 6.2 Amatrice earthquake, Central Italy. These different tests show that introducing uncertainties in Fault Geometry in the static inversion results in more sensible slip models. In practice, this augmented misfit covariance matrix reduces the confidence in the data points which are more sensitive to geometrical uncertainties as well as allowing for correlated misfits that are expected from the use of imperfect forward models. For most events, the uncertainties in both Fault Geometry and crustal structure will have a significant impact on the retrieved models, but the effect is expected to be stronger for large earthquakes (M>7) as epistemic uncertainties tend to scale with the amplitude of slip.
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accounting for uncertain Fault Geometry in earthquake source inversions i theory and simplified application
Geophysical Journal International, 2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:The ill-posed nature of earthquake source estimation derives from several factors including the quality and quantity of available observations and the fidelity of our forward theory. Observational errors are usually accounted for in the inversion process. Epistemic errors, which stem from our simplified description of the forward problem, are rarely dealt with despite their potential to bias the estimate of a source model. In this study, we explore the impact of uncertainties related to the choice of a Fault Geometry in source inversion problems. The Geometry of a Fault structure is generally reduced to a set of parameters, such as position, strike and dip, for one or a few planar Fault segments. While some of these parameters can be solved for, more often they are fixed to an uncertain value. We propose a practical framework to address this limitation by following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We develop a sensitivity analysis to small perturbations of Fault dip and position. The uncertainties of our fixed Fault Geometry are included in the inverse problem under the formulation of the misfit covariance matrix that combines both prediction and observation uncertainties. We validate this approach with the simplified case of a Fault that extends infinitely along strike, using both Bayesian and optimization formulations of a static slip inversion. If epistemic errors are ignored, predictions are overconfident in the data and slip parameters are not reliably estimated. In contrast, inclusion of uncertainties in Fault Geometry allows us to infer a robust posterior slip model. Epistemic uncertainties can be many orders of magnitude larger than observational errors for great earthquakes (Mw > 8). Not accounting for uncertainties in Fault Geometry may partly explain observed shallow slip deficits for continental earthquakes. Similarly, ignoring the impact of epistemic errors can also bias estimates of near-surface slip and predictions of tsunamis induced by megathrust earthquakes.
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the complete 3 d surface displacement field in the epicentral area of the 1999 mw7 1 hector mine earthquake california from space geodetic observations
Geophysical Research Letters, 2001Co-Authors: Yuri Fialko, Mark Simons, Duncan Carr AgnewAbstract:We use Interferometric Synthetic Aperture Radar (InSAR) data to derive continuous maps for three orthogonal components of the co-seismic surface displacement field due to the 1999 M_w7.1 Hector Mine earthquake in southern California. Vertical and horizontal displacements are both predominantly antisymmetric with respect to the Fault plane, consistent with predictions of linear elastic models of deformation for a strike-slip Fault. Some deviations from symmetry apparent in the surface displacement data may result from complexity in the Fault Geometry.
Théa Ragon - One of the best experts on this subject based on the ideXlab platform.
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Accounting for uncertain Fault Geometry in earthquake source inversions – II: application to the Mw 6.2 Amatrice earthquake, central Italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 Mw 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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accounting for uncertain Fault Geometry in earthquake source inversions ii application to the mw 6 2 amatrice earthquake central italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 M_w 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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Accounting for uncertain Fault Geometry in earthquake source inversion
2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Inferences of the history of Fault slip are subject to biases induced by unavoidable imperfections in the assumed forward model. For example, we commonly simplify assumed model of crustal properties and the Geometry of the Fault. The impacts of these choices are rarely investigated or quantified. Here, we explore the impact of uncertainties related to the choice of a Fault Geometry. To do so, we develop an augmented misfit covariance matrix which approximates the uncertainty related to the choice of a given Fault Geometry, following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We validate this approach with the simplified case of a Fault that extends infinitely along strike, investigating the impact of uncertainty in Fault dip and location. We apply our methodology to the 2016 Mw 6.2 Amatrice earthquake, Central Italy. These different tests show that introducing uncertainties in Fault Geometry in the static inversion results in more sensible slip models. In practice, this augmented misfit covariance matrix reduces the confidence in the data points which are more sensitive to geometrical uncertainties as well as allowing for correlated misfits that are expected from the use of imperfect forward models. For most events, the uncertainties in both Fault Geometry and crustal structure will have a significant impact on the retrieved models, but the effect is expected to be stronger for large earthquakes (M>7) as epistemic uncertainties tend to scale with the amplitude of slip.
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accounting for uncertain Fault Geometry in earthquake source inversions i theory and simplified application
Geophysical Journal International, 2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:The ill-posed nature of earthquake source estimation derives from several factors including the quality and quantity of available observations and the fidelity of our forward theory. Observational errors are usually accounted for in the inversion process. Epistemic errors, which stem from our simplified description of the forward problem, are rarely dealt with despite their potential to bias the estimate of a source model. In this study, we explore the impact of uncertainties related to the choice of a Fault Geometry in source inversion problems. The Geometry of a Fault structure is generally reduced to a set of parameters, such as position, strike and dip, for one or a few planar Fault segments. While some of these parameters can be solved for, more often they are fixed to an uncertain value. We propose a practical framework to address this limitation by following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We develop a sensitivity analysis to small perturbations of Fault dip and position. The uncertainties of our fixed Fault Geometry are included in the inverse problem under the formulation of the misfit covariance matrix that combines both prediction and observation uncertainties. We validate this approach with the simplified case of a Fault that extends infinitely along strike, using both Bayesian and optimization formulations of a static slip inversion. If epistemic errors are ignored, predictions are overconfident in the data and slip parameters are not reliably estimated. In contrast, inclusion of uncertainties in Fault Geometry allows us to infer a robust posterior slip model. Epistemic uncertainties can be many orders of magnitude larger than observational errors for great earthquakes (Mw > 8). Not accounting for uncertainties in Fault Geometry may partly explain observed shallow slip deficits for continental earthquakes. Similarly, ignoring the impact of epistemic errors can also bias estimates of near-surface slip and predictions of tsunamis induced by megathrust earthquakes.
Kaj M. Johnson - One of the best experts on this subject based on the ideXlab platform.
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inferred Fault Geometry and slip distribution of the 2010 jiashian taiwan earthquake is consistent with a thick skinned deformation model
Earth and Planetary Science Letters, 2011Co-Authors: Kuo En Ching, Kaj M. Johnson, Ruey Juin Rau, Ray Y Chuang, Longchen Kuo, Pei Ling LeuAbstract:Abstract We invert measurements of coseismic displacements from 139 continuously recorded GPS sites from the 2010, Jiashian, Taiwan earthquake to solve for Fault Geometry and slip distribution using an elastic uniform stress drop inversion. The earthquake occurred at a depth of ~ 23 km in an area between the Western Foothills fold-and-thrust belt and the crystalline high mountains of the Central Range, providing an opportunity to examine the deep Fault structure under Taiwan. The inferred rupture plane is oblique to the prominent orientation of thrust Faults and parallel to several previously recognized NW-striking transfer zones that appear to connect stepping thrusts. We find that a Fault striking 318°–344° with dip of 26°–41° fits the observations well with oblique reverse-sinistral slip under a low stress drop of about 0.5 MPa. The derived geodetic moment of 2.92 × 10 18 N-m is equivalent to a M w = 6.24 earthquake. Coseismic slip is largely concentrated within a circular patch with a 10-km radius at the depth between 10 and 24 km and maximum slip of 190 mm. We suggest this earthquake ruptured the NW-striking Chishan transfer Fault zone, which we interpret as a listric NE-dipping lateral ramp with oblique slip connecting stepping thrust Faults (ramps). The inferred slip on the lateral ramp is considerably deeper than the 7–15 km deep detachment identified in previous studies of western Taiwan. We infer an active basal detachment under western Taiwan at a depth of at least ~ 20–23 km based on these inversion results. The earthquake may have nucleated at the base of the lateral ramp near the intersection with the basal detachment. Coulomb stress change calculations suggest that this earthquake moved several NE-striking active thrust Faults in western Taiwan nearer to failure.
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mechanical constraints on inversion of coseismic geodetic data for Fault slip and Geometry example from insar observation of the 6 october 2008 mw 6 3 dangxiong yangyi tibet earthquake
Journal of Geophysical Research, 2011Co-Authors: Jianbao Sun, Kaj M. Johnson, Zhengkang Shen, Zhongquan Cao, Roland BurgmannAbstract:[1] Modern geodetic techniques, such as the global positioning system (GPS) and Interferometric Synthetic Aperture Radar (InSAR), provide high-precision deformation measurements of earthquakes. Through elastic models and mathematical optimization methods, the observations can be related to a slip distribution model. The classic linear, kinematic, and static slip inversion problem requires specification of a smoothing norm of slip parameters and a residual norm of the data and a choice about the relative weight between the two norms. Inversions for unknown Fault Geometry are nonlinear and, therefore, the Fault Geometry is often assumed to be known for the slip inversion problem. We present a new method to invert simultaneously for Fault slip and Fault Geometry assuming a uniform stress drop over the slipping area of the Fault. The method uses a full Bayesian inference method as an engine to estimate the posterior probability distribution of stress drop, Fault Geometry parameters, and Fault slip. We validate the method with a synthetic data set and apply the method to InSAR observations of a moderate-sized normal Faulting event, the 6 October 2008 Mw 6.3 Dangxiong-Yangyi (Tibet) earthquake. The results show a 45.0 ± 0.2° west dipping Fault with a maximum net slip of ∼1.13 m, and the static stress drop and rake angle are estimated as ∼5.43 MPa and ∼92.5°, respectively. The stress drop estimate falls within the typical range of earthquake stress drops known from previous studies.
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imaging the ramp decollement Geometry of the chelungpu Fault using coseismic gps displacements from the 1999 chi chi taiwan earthquake
Tectonophysics, 2004Co-Authors: Kaj M. Johnson, Paul SegallAbstract:Abstract We use coseismic GPS data from the 1999 Chi-Chi, Taiwan earthquake to estimate the subsurface shape of the Chelungpu Fault that ruptured during the earthquake. Studies prior to the earthquake suggest a ramp–decollement Geometry for the Chelungpu Fault, yet many finite source inversions using GPS and seismic data assume slip occurred on the down-dip extension of the Chelungpu ramp, rather than on a sub-horizontal decollement. We test whether slip occurred on the decollement or the down-dip extension of the ramp using well-established methods of inverting GPS data for Geometry and slip on Faults represented as elastic dislocations. We find that a significant portion of the coseismic slip did indeed occur on a sub-horizontal decollement located at ∼8 km depth. The slip on the decollement contributes 21% of the total modeled moment release. We estimate the Fault Geometry assuming several different models for the distribution of elastic properties in the earth: homogeneous, layered, and layered with lateral material contrast across the Fault. It is shown, however, that heterogeneity has little influence on our estimated Fault Geometry. We also investigate several competing interpretations of deformation within the E/W trending rupture zone at the northern end of the 1999 ground ruptures. We demonstrate that the GPS data require a 22- to 35-km-long lateral ramp at the northern end, contradicting other investigations that propose deformation is concentrated within 10 km of the Chelungpu Fault. Lastly, we propose a simple tectonic model for the development of the lateral ramp.
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Fault Geometry and slip distribution of the 1999 Chi-Chi, Taiwan earthquake imaged from inversion of GPS data
Geophysical Research Letters, 2001Co-Authors: Kaj M. Johnson, Ya-ju Hsu, Paul SegallAbstract:GPS measurements of coseismic displacements from the 1999, Chi-Chi, Taiwan earthquake are modeled using elastic dislocation theory. We find that a single Fault plane cannot fit the data, but rather a curved Fault surface consisting of multiple segments dipping 20–25° best fits the observations. The model Fault exhibits reverse and left-lateral slip on a 75 km long N-S trending segment and reverse and right-lateral slip on a 25 km E-W trending segment at the northern end of the rupture. The 21° dipping E-W segment is inconsistent with previous interpretations of high angle tear Faulting.
Paul Segall - One of the best experts on this subject based on the ideXlab platform.
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imaging the ramp decollement Geometry of the chelungpu Fault using coseismic gps displacements from the 1999 chi chi taiwan earthquake
Tectonophysics, 2004Co-Authors: Kaj M. Johnson, Paul SegallAbstract:Abstract We use coseismic GPS data from the 1999 Chi-Chi, Taiwan earthquake to estimate the subsurface shape of the Chelungpu Fault that ruptured during the earthquake. Studies prior to the earthquake suggest a ramp–decollement Geometry for the Chelungpu Fault, yet many finite source inversions using GPS and seismic data assume slip occurred on the down-dip extension of the Chelungpu ramp, rather than on a sub-horizontal decollement. We test whether slip occurred on the decollement or the down-dip extension of the ramp using well-established methods of inverting GPS data for Geometry and slip on Faults represented as elastic dislocations. We find that a significant portion of the coseismic slip did indeed occur on a sub-horizontal decollement located at ∼8 km depth. The slip on the decollement contributes 21% of the total modeled moment release. We estimate the Fault Geometry assuming several different models for the distribution of elastic properties in the earth: homogeneous, layered, and layered with lateral material contrast across the Fault. It is shown, however, that heterogeneity has little influence on our estimated Fault Geometry. We also investigate several competing interpretations of deformation within the E/W trending rupture zone at the northern end of the 1999 ground ruptures. We demonstrate that the GPS data require a 22- to 35-km-long lateral ramp at the northern end, contradicting other investigations that propose deformation is concentrated within 10 km of the Chelungpu Fault. Lastly, we propose a simple tectonic model for the development of the lateral ramp.
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Fault Geometry and slip distribution of the 1999 Chi-Chi, Taiwan earthquake imaged from inversion of GPS data
Geophysical Research Letters, 2001Co-Authors: Kaj M. Johnson, Ya-ju Hsu, Paul SegallAbstract:GPS measurements of coseismic displacements from the 1999, Chi-Chi, Taiwan earthquake are modeled using elastic dislocation theory. We find that a single Fault plane cannot fit the data, but rather a curved Fault surface consisting of multiple segments dipping 20–25° best fits the observations. The model Fault exhibits reverse and left-lateral slip on a 75 km long N-S trending segment and reverse and right-lateral slip on a 25 km E-W trending segment at the northern end of the rupture. The 21° dipping E-W segment is inconsistent with previous interpretations of high angle tear Faulting.
Anthony Sladen - One of the best experts on this subject based on the ideXlab platform.
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Accounting for uncertain Fault Geometry in earthquake source inversions – II: application to the Mw 6.2 Amatrice earthquake, central Italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 Mw 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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accounting for uncertain Fault Geometry in earthquake source inversions ii application to the mw 6 2 amatrice earthquake central italy
Geophysical Journal International, 2019Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Our understanding of earthquake sources is limited by the availability and the quality of observations and the fidelity of our physical models. Uncertainties in our physical models will naturally bias our inferences of subsurface Fault slip. These uncertainties will always persist to some level as we will never have a perfect knowledge of the Earth’s interior. The choice of the forward physics is thus ambiguous, with the frequent need to fix the value of several parameters such as crustal properties or Fault Geometry. Here, we explore the impact of uncertainties related to the choice of both Fault Geometry and elastic structure, as applied to the 2016 M_w 6.2 Amatrice earthquake, central Italy. This event, well instrumented and characterized by a relatively simple Fault morphology, allows us to explore the role of uncertainty in basic Fault parameters, such as Fault dip and position. We show that introducing uncertainties in Fault Geometry in a static inversion reduces the sensitivity of inferred models to different geometric assumptions. Accounting for uncertainties thus helps infer more realistic and robust slip models. We also show that uncertainties in Fault Geometry and Earth’s elastic structure significantly impact estimated source models, particularly if near-Fault observations are available.
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Accounting for uncertain Fault Geometry in earthquake source inversion
2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:Inferences of the history of Fault slip are subject to biases induced by unavoidable imperfections in the assumed forward model. For example, we commonly simplify assumed model of crustal properties and the Geometry of the Fault. The impacts of these choices are rarely investigated or quantified. Here, we explore the impact of uncertainties related to the choice of a Fault Geometry. To do so, we develop an augmented misfit covariance matrix which approximates the uncertainty related to the choice of a given Fault Geometry, following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We validate this approach with the simplified case of a Fault that extends infinitely along strike, investigating the impact of uncertainty in Fault dip and location. We apply our methodology to the 2016 Mw 6.2 Amatrice earthquake, Central Italy. These different tests show that introducing uncertainties in Fault Geometry in the static inversion results in more sensible slip models. In practice, this augmented misfit covariance matrix reduces the confidence in the data points which are more sensitive to geometrical uncertainties as well as allowing for correlated misfits that are expected from the use of imperfect forward models. For most events, the uncertainties in both Fault Geometry and crustal structure will have a significant impact on the retrieved models, but the effect is expected to be stronger for large earthquakes (M>7) as epistemic uncertainties tend to scale with the amplitude of slip.
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accounting for uncertain Fault Geometry in earthquake source inversions i theory and simplified application
Geophysical Journal International, 2018Co-Authors: Théa Ragon, Anthony Sladen, Mark SimonsAbstract:The ill-posed nature of earthquake source estimation derives from several factors including the quality and quantity of available observations and the fidelity of our forward theory. Observational errors are usually accounted for in the inversion process. Epistemic errors, which stem from our simplified description of the forward problem, are rarely dealt with despite their potential to bias the estimate of a source model. In this study, we explore the impact of uncertainties related to the choice of a Fault Geometry in source inversion problems. The Geometry of a Fault structure is generally reduced to a set of parameters, such as position, strike and dip, for one or a few planar Fault segments. While some of these parameters can be solved for, more often they are fixed to an uncertain value. We propose a practical framework to address this limitation by following a previously implemented method exploring the impact of uncertainties on the elastic properties of our models. We develop a sensitivity analysis to small perturbations of Fault dip and position. The uncertainties of our fixed Fault Geometry are included in the inverse problem under the formulation of the misfit covariance matrix that combines both prediction and observation uncertainties. We validate this approach with the simplified case of a Fault that extends infinitely along strike, using both Bayesian and optimization formulations of a static slip inversion. If epistemic errors are ignored, predictions are overconfident in the data and slip parameters are not reliably estimated. In contrast, inclusion of uncertainties in Fault Geometry allows us to infer a robust posterior slip model. Epistemic uncertainties can be many orders of magnitude larger than observational errors for great earthquakes (Mw > 8). Not accounting for uncertainties in Fault Geometry may partly explain observed shallow slip deficits for continental earthquakes. Similarly, ignoring the impact of epistemic errors can also bias estimates of near-surface slip and predictions of tsunamis induced by megathrust earthquakes.
