The 6 June 2003 Bardwell, Kentucky, Earthquake Sequence: Evidence for a Locally Perturbed Stress Field in the Mississippi Embayment

Horton, Steve; Kim, Youn-Jung; Withers, Mitch

doi:10.1785/0120040052

Cited by 23 publications

(13 citation statements)

References 58 publications

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“…80 • , Ellis 1994), many stress orientations inferred from focal mechanism data within the seismic zone lie subparallel to the strike of the rift (e.g. Ellis 1994;Horton et al 2005). The truncation of seismicity by the relatively aseismic rift margin is similar to the behaviour at the CSZ.…”

Section: Discussionmentioning

confidence: 95%

Stress channelling and partitioning of seismicity in the Charlevoix seismic zone, Québec, Canada

Baird¹,

McKinnon²,

Godin³

2009

Geophysical Journal International

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S U M M A R YThe Charlevoix seismic zone (CSZ) in the St Lawrence valley of Québec is historically the most active in eastern Canada. The structurally complex region comprises rift faults formed during the opening of the Iapetus Ocean, superimposed by a 350 Ma meteorite impact structure, resulting in a circular highly fractured zone. Although seismicity is localized along two steeply dipping planar rift-parallel zones, previous work indicates that most of the large-scale rift faults bound the low magnitude background seismicity rather than generate earthquakes themselves. In order to gain insight into the mechanics of the partitioning of this seismicity, a 2-D model of the CSZ was built using the stress analysis code FLAC. The rift faults are represented by frictional discontinuities. The heavily fractured impact structure is represented by an elastic continuum of reduced modulus. Boundary displacements are used to generate a regional stress field with the major horizontal component in the direction of tectonic loading. Given a high strength, the rift faults have little effect on the stress patterns. Stress trajectories naturally flow around the crater of reduced elastic modulus, leaving the fractured area with lower stresses than the background level. However, when the rift faults have low strength, they are unable to support stress trajectories inclined to them, due to the resolved shear stress exceeding their strength. This prevents trajectories from flowing out of the rift, effectively channelling higher magnitude stresses into the region of the impact structure between the faults. Low-strength bounding faults can thus explain the localization of seismicity into linear bands, rather than distributed seismicity throughout the impact structure. It also explains how the rift faults act as boundaries to regions of low magnitude seismicity. These results indicate that the interplay between faults of varying strength and zones of differing elastic modulus can give rise to complicated stress patterns, and can explain many of the seismicity patterns observed in the CSZ. This has implications for other intraplate seismic zones, as it shows an example of how regional weak faults can modify stress conditions around local structures and drive seismicity. The results are particularly relevant for other regions located within rifted crust, such as the New Madrid seismic zone, which possibly display evidence of stress channelling.

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Section: Discussionmentioning

confidence: 95%

Stress channelling and partitioning of seismicity in the Charlevoix seismic zone, Québec, Canada

Baird¹,

McKinnon²,

Godin³

2009

Geophysical Journal International

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“…Prejean et al [26] found that the local stress field of Long Valley Caldera rotated systematically form NE in the north part to SW in the south part, and the numerical simulation shows that this perturbation correlated with tectonic activities of large scale. Stephen et al [27] studied the M w4.2 Bardwell earthquake occurred on June 6, 2003 in America, they found that in a small area of 60 km around the source, strong stress field perturbation was observed. Kato et al [28] found that the stress field rotated 20 • counter clockwise spatially.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Moment Tensor Inversion of Moderate Earthquakes and the Locally Perturbed Stress Field in the Jiashi Source Region

Zhao¹,

Chen²,

Zheng³

et al. 2008

Chinese J of Geophysics

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Moment tensors of 52 moderate sized earthquakes occurred in Jiashi source region, Xinjiang, from 1997 to 2004 were determined in time domain by using the long period waveforms recorded by regional broadband stations. The results demonstrate significant variations of the orientation and plunge of P, T and N axis from west to east in the source region. Therefore, we further divided the whole region into two parts, which are called the western part and the eastern part, and performed the stress tensor inversion respectively. The results show that in the eastern part, the maximum principal axis σ1 is almost horizontal and trends N321°E, the minimum principal axis σ3 trends 68° with a plunge of 40°, and σ2 trends 213°; with a plunge about 40°;. Till 2004, the stress within the western part remains stable, with the σ1 and σ3 nearly horizontal and trending to N12°E and N282°E respectively, the middle axis σ2 almost vertical. Thus the maximum principal stress σ1 significantly rotates counter clockwise from N10°E in the west part to N39°W in the east part across the whole studied region. Compared with the stress field in the eastern part, the western part is under a stronger horizontal extension effect. This lateral perturbation of stress field is consistent with the pattern of crustal deformation rate from GPS observation, as well as the topography map at the structure boundary between Tarim basin and Tienshan. We infer that both the sharp deformation in the deep crust and the large‐scale NNW trending Puchang and Selibuya fault structures may play a crucial role in resulting in the local stress perturbation pattern.

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“…Although central and eastern North America constitute an intraplate setting, several large earthquakes have occurred there over the past three centuries (Bent, 1995(Bent, , 1996Du et al, 2003;Ebel, 2009;Horner et al, 1978;Horton et al, 2005;Hough & Page, 2011;Kim, 2003;Kim & Chapman, 2005;Kim et al, 2006;Ma et al, 2008;Neely et al, 2018;Sbar et al, 1975;Yang & Aggarwal, 1981). Most notable are the New Madrid earthquakes and their aftershocks that shook the Midwest between 1811 and 1812 and the 1886 Charleston earthquake in South Carolina.…”

Section: Introductionmentioning

confidence: 99%

Role of Large‐Scale Tectonic Forces in Intraplate Earthquakes of Central and Eastern North America

Ghosh

Holt

Bahadori

2019

Geochem Geophys Geosyst

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Central and eastern United States (CEUS) have experienced large intraplate earthquakes. Yet, at present there is no comprehensive model to explain stresses, strain, and seismicity in this intraplate setting. Models to explain the intraplate stresses in CEUS include glacio‐isostatic adjustment, ridge push effects, local stresses along preexisting fracture zones, and large‐scale convection. In this paper, we present a self‐consistent model of the dynamics of CEUS that explains the stress field responsible for these intraplate earthquakes. The earthquakes represent slow, ongoing deformation associated with forces arising from a combination of lithosphere topography and structure, together with the effects of density‐driven mantle flow. Using GPS data, we calculate strain rates that are likely to arise from tectonic effects and conclude that intraplate strain rates associated with tectonic effects are unlikely to exceed 1 × 10−9 year−1. We test several models of lateral viscosity variations by comparing model stress orientation output with earthquake moment tensors, SHmax directions from stress inversion, and P axes of earthquakes. A model that satisfies stress and earthquake constraints and also strain rate magnitude constraints requires high viscosity (1025 Pa·s) craton and old oceanic lithosphere of the western Atlantic block and weaker (5 × 1024 Pa·s) accreted Appalachian terrane. Other strength contrasts within the lithosphere are likely present. Incorporation of these into future models using constraints from seismology, along with refined geodetic measurements and improved estimates of crust and upper mantle densities, is needed to further refine long‐term dynamic models and better evaluate the hazards associated with this very slow, ongoing permanent deformation within the eastern and central United States.

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The 6 June 2003 Bardwell, Kentucky, Earthquake Sequence: Evidence for a Locally Perturbed Stress Field in the Mississippi Embayment

Cited by 23 publications

References 58 publications

Stress channelling and partitioning of seismicity in the Charlevoix seismic zone, Québec, Canada

Stress channelling and partitioning of seismicity in the Charlevoix seismic zone, Québec, Canada

Moment Tensor Inversion of Moderate Earthquakes and the Locally Perturbed Stress Field in the Jiashi Source Region

Role of Large‐Scale Tectonic Forces in Intraplate Earthquakes of Central and Eastern North America

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