Stress Change and Fault Interaction from a Two Century‐Long Earthquake Sequence in the Central Tell Atlas, Algeria

Kariche, Jugurtha; Meghraoui, Mustapha; Ayadi, Abdelhakim; Boughacha, Mohamed Salah

doi:10.1785/0120170041

Cited by 18 publications

(5 citation statements)

References 41 publications

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“…This kind of stress increases following a given major seismic event (e.g., Al Asnam) and can dominate the stress field near the fault (Špičák, ) with possibility of its migration from a segment fault to another. This is in agreement with the model of a stress transfer by the northeast trending earthquake migration along the Tell thrust‐and‐tear faults (Kariche et al, ; Lin et al, ). Another example of second‐order sources of stress is the gravitational potential energy (Coblentz et al, ; Ghosh et al, ; Rajabi et al, ; Zoback, ), which characterizes the Alboran/Rif block (Palano et al, ).…”

Section: Discussionsupporting

confidence: 90%

“…Several focal solutions of main shocks illuminate the existence of particular NW to E‐W dextral strike‐slip faulting. The NW oriented faults are suitable for R shears, while the NE‐SW oriented faults would behave as X ‐conjugated shears along which occurs the significant stress release (Kariche et al, ). We also consider active as X‐shears faults that were reactivated during the 1999 Ain Temouchent earthquake ( M w 5.9) and the 1980 El Asnam earthquake ( M w 7.3) as reverse faults with a left‐lateral slip (Ayadi et al, ; Belabbes et al, ; Ousadou et al, ).…”

Section: Active Strike‐slip Fault Systems Of the Maghrebmentioning

confidence: 99%

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Active Faulting Geometry and Stress Pattern Near Complex Strike‐Slip Systems Along the Maghreb Region: Constraints on Active Convergence in the Western Mediterranean

et al. 2018

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The Maghreb region (from Tunisia to Gibraltar) is a key area in the western Mediterranean to study the active tectonics and stress pattern across the Africa‐Eurasia convergent plate boundary. In the present study, we compile comprehensive data set of well‐constrained crustal stress indicators (from single focal mechanism solutions, formal inversion of focal mechanism solutions, and young geologic fault slip data) based on our and published data analyses. Stress inversion of focal mechanisms reveals a first‐order transpression‐compatible stress field and a second‐order spatial variation of tectonic regime across the Maghreb region, with a relatively stable SHmax orientation from east to west. Therefore, the present‐day active contraction of the western Africa‐Eurasia plate boundary is accommodated by (1) E‐W strike‐slip faulting with reverse component along the Eastern Tell and Saharan‐Tunisian Atlas, (2) a predominantly NE trending thrust faulting with strike‐slip component in the Western Tell part, and (3) a conjugate strike‐slip faulting regime with normal component in the Alboran/Rif domain. This spatial variation of the present‐day stress field and faulting regime is relatively in agreement with the inferred stress information from neotectonic features. According to existing and newly proposed structural models, we highlight the role of main geometrically complex shear zones in the present‐day stress pattern of the Maghreb region. Then, different geometries of these major inherited strike‐slip faults and its related fractures (V‐shaped conjugate fractures, horsetail splays faults, and Riedel fractures) impose their component on the second‐ and third‐order stress regimes. Neotectonic and smoothed present‐day stress map (mean SHmax orientation) reveal that plate boundary forces acting on the Africa‐Eurasia collisional plates control the long wavelength of the stress field pattern in the Maghreb. The current tectonic deformations and the upper crustal stress field in the study area are governed by the interplay of the oblique plate convergence (i.e., Africa‐Eurasia), lithosphere‐mantle interaction, and preexisting tectonic weakness zones.

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Section: Discussionsupporting

confidence: 90%

Section: Active Strike‐slip Fault Systems Of the Maghrebmentioning

confidence: 99%

Active Faulting Geometry and Stress Pattern Near Complex Strike‐Slip Systems Along the Maghreb Region: Constraints on Active Convergence in the Western Mediterranean

et al. 2018

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“…The structural characteristics of tectonic blocks limited by active and seismogenic faults with en echelon fault geometry provide the patterns of earthquake stress transfer as for the case of a simple pure shear deformation applied to oblique plate convergence (Kariche et al., 2017). In addition to other tectonic patterns, the remaining question in Central Walker Lane is the role of fluid migration following the occurrence of large earthquakes.…”

Section: Discussionmentioning

confidence: 99%

“…Among the largest earthquakes (Mw > 6) to have occurred in the Central Walker Lane, the 1932 Cedar Mountain (Mw 7.1), the 1934 Excelsior Mountain (Mw 6.3) and the 2020 Monte Cristo (Mw 6.5) seismic sequences suggest a southward migrating pattern of seismicity (Figures 3a–3c). In comparison with the stress transfer controlled by en echelon thrust faults related to the transpressive regime with a clockwise “pinned” block rotation that characterizes the oblique convergence in the western Mediterranean region (Kariche et al., 2017), the earthquake activity in the Central Walker Lane appears to be controlled by a set of conjugate strike slip faults. The seismotectonic analysis shows a clear distinction between moderate size‐earthquakes that occurred along the en echelon ENE‐WSW sinistral strike slip faults and large earthquakes that occurred along NNW‐SSE dextral strike slip faults that are conjugate to them (Figure 1).…”

Section: Earthquake Sequence and Static Stress Change In The Central ...mentioning

confidence: 99%

The 2020 Monte Cristo (Nevada) Earthquake Sequence: Stress Transfer in the Context of Conjugate Strike‐Slip Faults

Kariche

2022

Tectonics

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On 15 May 2020 at 11:03 (UTC) a shallow earthquake with a Magnitude Mw 6.5 struck the Central Walker Lane in the Mina Deflection region. This shallow event offers the possibility to model the change in Coulomb failure function (ΔCFF) including the historical events and to analyze the effect of fluid redistribution on fault ruptures. The static stress change modeling shows that the 1932 Cedar Mountain (Mw 7.1) earthquake increased ΔCFF on the 2020 Monte Cristo left‐lateral rupture by an average value of ∼2 bar suggesting a fault interaction in the context of conjugate strike‐slip faults. Also, the ΔCFF caused by the Monte Cristo earthquake shows a 0.1–0.5 bar increase on nearby right‐lateral fault planes at 8 km depth. In contrast to the 2019 Ridgecrest sequence (Mw 6.4 and Mw 7.1), our poroelastic stress change modeling of the 2020 Monte Cristo earthquake shows no apparent correlation between the positive stress change values and fluid redistribution along the Monte Cristo conjugated ruptures. Nevertheless, the Coulomb modeling using adapted poroelastic solutions shows that the 2020 Monte Cristo mainshock increased stresses with a value of 0.2–0.9 bar south of the Mina Deflection along the White Mountains and Fish Lake Valley fault zones. The stress values combined with a strain rate of 40–50 nanostrain/yr represent a shift of 8%–15% of the recurrence time interval for a large earthquake along the White Mountains and Fish Lake Valley faults suggesting an elevated pore‐fluid effect for faults reactivation in both undrained and drained fluid conditions.

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“…We simulate the static stress transfer following the first event of the seismic sequence in an elastic half-space (Okada, 1992) using the Coulomb 3.4 software package (Lin & Stein, 2004;Toda et al, 2005). We assume a shear modulus l = 3.2 9 10 5 bar, Poisson's ratio v = 0.25, and l' = 0.4 (Beldjoudi, 2020;Dabouz & Beldjoudi, 2019;Kariche et al, 2017;Khelif et al, 2018;King et al, 1994;Lin et al, 2011;Semmane, 2005). The source parameters that are obtained from waveform modeling of the fault segments are given in Table 11.…”

Section: Coulomb Stress Transfermentioning

confidence: 99%

The 2007 Medea Seismic Sequence, North-Central Algeria: Source Parameters, Stress Tensor, and Static Stress Changes

Dabouz

Beldjoudi

Delouis

et al. 2021

Pure Appl. Geophys.

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Dense seismic networks provide the opportunity to better understand seismogenic processes in tectonically active regions. The Algerian Digital Seismic Network was strengthened following the 10 October 1980 Ms 7.3 El Asnam and 21 May 2003 Mw 6.8 Bournerdes earthquakes, such that the source parameters of small-to moderate-magnitude earthquakes in northern Algeria can now be computed. Here we examine the 2007 seismic sequence recorded in the Medea region (north-central part of Algeria). We calculate the seismic sources of three moderate events that occurred between May and August 2007 using near-field waveform modeling, and obtain moment magnitudes of 4.4, 4.1, and 4.6, with fault planes oriented N63°E, N15°E, and N219°E, respectively. We use displacement spectra to estimate the corner frequency f c and spectral flat level then use these to recalculate the seismic moment and moment magnitude. The stress tensor obtained by inverting 13 focal mechanisms from events near the 2007 sequence exhibits a well-constrained compressional axis with a subhorizontal N335°Etrending r 1 axis (plunge 7°). We calculate the static stress changes to understand the connections between these three events. The results indicate an interaction between the faults related to these events during the earthquake sequence. We conclude that these events likely occurred on the unstudied extensions of mapped faults, and that the epicentral area therefore has moderate seismogenic potential.

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Stress Change and Fault Interaction from a Two Century‐Long Earthquake Sequence in the Central Tell Atlas, Algeria

Cited by 18 publications

References 41 publications

Active Faulting Geometry and Stress Pattern Near Complex Strike‐Slip Systems Along the Maghreb Region: Constraints on Active Convergence in the Western Mediterranean

Active Faulting Geometry and Stress Pattern Near Complex Strike‐Slip Systems Along the Maghreb Region: Constraints on Active Convergence in the Western Mediterranean

The 2020 Monte Cristo (Nevada) Earthquake Sequence: Stress Transfer in the Context of Conjugate Strike‐Slip Faults

The 2007 Medea Seismic Sequence, North-Central Algeria: Source Parameters, Stress Tensor, and Static Stress Changes

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