Fault rupture and stress changes associated with the November 27, 2005 Qeshm Island (Iran) earthquake (MW = 6.0)

Utkucu, Murat; Kızılbuğa, Serap; Arman, Hasan

doi:10.1007/s12517-018-4090-5

Cited by 3 publications

(2 citation statements)

References 49 publications

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“…Following the same methodology and inversion procedure detailed in the co-seismic slip studies of Utkucu et al, (2018) and Durmuş and Utkucu, (2021), we performed a nite-fault source inversion method, rst described by Hartzell and Heaton, (1983), to constrain the co-seismic slip distributions across the fault plane models of the rst and second mainshocks (Eq. 1 and Eq.…”

Section: Finite-fault Source Inversionmentioning

confidence: 99%

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Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) North Bandar Abbas doublet earthquakes in Fin region, SE-syntaxis of Zagros, Iran: new insights into the tectonic deformation decoupling process

Toker,

Durmuş,

Utkucu

2023

Environ Earth Sci

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The co-seismic properties of the Mw 6.0 (12:07:03 UTC) and Mw 6.4 (12:08:06 UTC) earthquakes that took place on 14 November 2021, Bandar Abbas Syntaxis, SE-Zagros Simply Folded Belt (SFB), Iran, are thoroughly examined. Understanding the earthquake ruptures and their relationship to the co-seismic deformations, critical to our knowledge about the earthquake source mechanisms, has provided a singular chance to interpret the details of the rupture procedure of these two interrelated earthquakes, to complement previous studies of seismicity. Here, using nite-fault source inversion, we rst estimated the co-seismic source models and then the co-seismic displacements during the earthquakes, differentiated into vertical/horizontal components. We inverted the observed teleseismic broadband P-velocity waveforms of the earthquakes to simultaneously estimate the nite-fault rupture process, the slip distribution, the fault geometry and the stress changes. We found that the earthquakes were typical blind thrust-fault types along NW-SE and NE-SW striking fault lengths of ~40-50 km, widths of ~25-30 km, at a depth range of ~3-16 km and ~3-15 km, respectively, with co-seismic surface folding (~7-10 km) to NE controlled by a salt décollement layer at a depth range of ~10-12 km. We also found that the earthquakes consisted of relatively fast rupture sources (V R 3.3 km/s); an initial pure thrust faulting bilateral rupture at a depth of 12 km with a maximum slip of 30 cm and a dip angle of 32 o , which was followed by a bilateral rupture with an oblique-slip left-lateral thrust faulting at a depth of 10 km, with a maximum slip of 80 cm and a dip angle of 24 o propagated towards the NE. The joint interpretation of estimated Coulomb stress changes imparted by proposed variable slip rupture models, and the salt layer indicated that the stress increased load, triggered the fault planes of both events and in uenced along-strike co-seismic strain distribution, providing evidence for the SW-NE trending activation of the stress decoupling between the ruptures, corresponding to the salt décollement. The initial pure thrust motion ruptured and mobilized the salt layer, then triggered and activated the bilateral rupture that generated the co-seismic detachment folds subparallel to the décollement. The weak salt, co-seismically ruptured and rapidly activated, compensated for co-seismic strain through lateral thickness changes from SW to NE and obliquely accommodated the folding in the shallow cover. Thus, basal ductile shear facilitated the change from pure thrust faulting in the basement to oblique thrust faulting in the cover. This nding clari es differences in rupturing properties and deformation styles of such low-angle thrust faults. Anomalous interference patterns through superimposed fault planes of the Bandar Abbas earthquakes with the salt horizon have illuminated the rupture decoupling process and stress changes of the successive thick-/thinskinned earthquakes, typical of the Zagros SFB. al., 2011) and centroid depths of high-quality...

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Section: Finite-fault Source Inversionmentioning

confidence: 99%

“…1 and Eq. 2) regarding the previous fault source models (Utkucu et al, 2018;Durmuş and Utkucu, 2021).…”

Section: Finite-fault Source Inversionmentioning

confidence: 99%

Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) North Bandar Abbas doublet earthquakes in Fin region, SE-syntaxis of Zagros, Iran: new insights into the tectonic deformation decoupling process

Toker,

Durmuş,

Utkucu

2023

Environ Earth Sci

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Coseismic slip distributions and stress interactions of the November 12, 2017, Sarpole-Zahab (Western Iran) earthquake (MW=7.3) and its aftershocks: seismotectonic implications

Durmuş

Utkucu

2021

Arab J Geosci

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Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) Bandar Abbas earthquakes, SE-Syntaxis of Zagros, Iran; New insights into the rupture decoupling process

Toker

Durmuş

Utkucu

2023

Preprint

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The co-seismic properties of the Mw 6.0 (12:07:03 UTC) and Mw 6.4 (12:08:06 UTC) earthquakes that took place on 14 November 2021, Bandar Abbas Syntaxis, SE-Zagros Simply Folded Belt (SFB), Iran, are thoroughly examined. Understanding the earthquake ruptures and their relationship to the co-seismic deformations, critical to our knowledge about the earthquake source mechanisms, has provided a singular chance to interpret the details of the rupture procedure of these two interrelated earthquakes, to complement previous studies of seismicity. Here, using finite-fault source inversion, we first estimated the co-seismic source models and then the co-seismic displacements during the earthquakes, differentiated into vertical/horizontal components. We inverted the observed teleseismic broadband P-velocity waveforms of the earthquakes to simultaneously estimate the finite-fault rupture process, the slip distribution, the fault geometry and the stress changes. We found that the earthquakes were typical blind thrust-fault types along NW-SE and NE-SW striking fault lengths of ~40-50 km, widths of ~25-30 km, at a depth range of ~3-16 km and ~3-15 km, respectively, with co-seismic surface folding (~7-10 km) to NE controlled by a salt décollement layer at a depth range of ~10-12 km. We also found that the earthquakes consisted of relatively fast rupture sources (VR 3.3 km/s); an initial pure thrust faulting bilateral rupture at a depth of 12 km with a maximum slip of 30 cm and a dip angle of 32o, which was followed by a bilateral rupture with an oblique-slip left-lateral thrust faulting at a depth of 10 km, with a maximum slip of 80 cm and a dip angle of 24o propagated towards the NE. The joint interpretation of estimated Coulomb stress changes imparted by proposed variable slip rupture models, and the salt layer indicated that the stress increased load, triggered the fault planes of both events and influenced along-strike co-seismic strain distribution, providing evidence for the SW-NE trending activation of the stress decoupling between the ruptures, corresponding to the salt décollement. The initial pure thrust motion ruptured and mobilized the salt layer, then triggered and activated the bilateral rupture that generated the co-seismic detachment folds subparallel to the décollement. The weak salt, co-seismically ruptured and rapidly activated, compensated for co-seismic strain through lateral thickness changes from SW to NE and obliquely accommodated the folding in the shallow cover. Thus, basal ductile shear facilitated the change from pure thrust faulting in the basement to oblique thrust faulting in the cover. This finding clarifies differences in rupturing properties and deformation styles of such low-angle thrust faults. Anomalous interference patterns through superimposed fault planes of the Bandar Abbas earthquakes with the salt horizon have illuminated the rupture decoupling process and stress changes of the successive thick-/thin-skinned earthquakes, typical of the Zagros SFB.

show abstract

Fault rupture and stress changes associated with the November 27, 2005 Qeshm Island (Iran) earthquake (MW = 6.0)

Cited by 3 publications

References 49 publications

Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) North Bandar Abbas doublet earthquakes in Fin region, SE-syntaxis of Zagros, Iran: new insights into the tectonic deformation decoupling process

Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) North Bandar Abbas doublet earthquakes in Fin region, SE-syntaxis of Zagros, Iran: new insights into the tectonic deformation decoupling process

Coseismic slip distributions and stress interactions of the November 12, 2017, Sarpole-Zahab (Western Iran) earthquake (MW=7.3) and its aftershocks: seismotectonic implications

Decoupled co-seismic deformation and stress changes during the 2021 (Mw 6.0, 6.4) Bandar Abbas earthquakes, SE-Syntaxis of Zagros, Iran; New insights into the rupture decoupling process

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