The 2015–2017 Pamir earthquake sequence: foreshocks, main shocks and aftershocks, seismotectonics, fault interaction and fluid processes

Bloch, Wasja; Metzger, Sabrina; Schurr, Bernd; Yuan, Xiaohui; Ratschbacher, Lothar; Reuter, Sanaa; Xu, Qiang; Zhao, Junmeng; Murodkulov, Shohrukh; Oimuhammadzoda, Ilhomjon

doi:10.1093/gji/ggac473

Cited by 3 publications

(1 citation statement)

References 141 publications

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“…5), and because the poroelastic ∆CFS values are much larger than a critical triggering value of +0.1 bar 2,7 in the region where most of the upperplate aftershocks occur. This contrasts the widely used ∆CFS estimation to investigate aftershock sequences based on coseismic stress changes derived from purely elastic models in all tectonic settings 2,5,7,8,41 , where stress changes are generally much smaller and which fail to explain the time-dependency. This time dependency could be explained by the exponential decay of afterslip 12,42 or non-linear viscoelastic relaxation 43 , but the estimation of ∆CFS resulting from these processes is highly sensitive to the used fault orientation and the assumed style of faulting, respectively.…”

Section: Pore-pressure Diffusion In the Upper Platementioning

confidence: 65%

Pore-pressure diffusion controls upper-plate aftershocks of the 2014 Iquique earthquake

Peña

Heidbach

Metzger

et al. 2023

Preprint

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Upper-plate aftershocks following megathrust earthquakes are particularly dangerous as they may occur close to the highly populated shore. Aftershock numbers decay with time, imposing a time-dependent seismic hazard. While coseismic stress transfer cannot explain this time-dependency, transient postseismic deformation due to afterslip, viscoelastic relaxation, and pore-pressure diffusion are potential candidates. We investigate which of these three processes is the key driver of the upper-plate aftershocks following the 2014 Mw=8.1 Iquique, northern Chile, earthquake. We first use a 4D (space and time) model to reproduce the postseismic deformation observed in geodetic data. We then analyze the spatiotemporal stress changes produced by individual postseismic processes and compare them to the distribution of upper-plate aftershocks. Our results reveal that stresses produced by coseismically-induced pore-pressure diffusion best correlate in space and time with increased upper-plate aftershock activity. Moreover, an increase in pore-pressure diffusion reduces the three principal stresses likewise. Hence, all faults, regardless of their orientation, are brought closer to failure. This may explain the diversity of faulting styles of upper-plate aftershocks. Our findings provide new insights into the link between pore-pressure diffusion and upper-plate deformation in subduction zones with implications for time-dependent seismic hazard assessment.

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Section: Pore-pressure Diffusion In the Upper Platementioning

confidence: 65%

Pore-pressure diffusion controls upper-plate aftershocks of the 2014 Iquique earthquake

Peña

Heidbach

Metzger

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

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Stress triggering and future seismic hazards implied by four large earthquakes in the Pamir from 2015 to 2023 revealed by Sentinel-1 radar interferometry

Liu,

Li,

et al. 2024

Geophysical Journal International

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Summary The Mw 6.8 Murghob earthquake is the third earthquake in an Mw 6.4+ sequence occurring in the Pamir initiated by the 2015 Sarez Mw 7.2 earthquake. It is of great significance to investigate their interactions and to assess future seismic hazards in the region. In this paper, we use Sentinel-1 radar interferometric data to retrieve coseismic deformation, invert for the slip distributions of the four events, and then investigate their interactions. The cumulative Coulomb failure stress changes (ΔCFS) suggest that the 2023 Murghob earthquake was promoted by the three prior earthquakes in the sequence. Pre-stress from historical earthquakes is a key factor in explaining the triggering mechanism of the two 2016 Mw 6.4+ earthquakes. Stress loading and unloading effects on major faults in the region indicate that future attention should be paid in 1) the segment of the Sarez-Karakul fault north of the Kokuibel Valley, 2) the segment of the Sarez-Murghab thrust fault west of the Sarez-Karakul fault, and 3) the east segments of the Pamir thrust fault system, all with a large positive ΔCFS.

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The N-S direction strike-slip activities in the Pamir hinterland under oblique convergence: the 2015 and 2023 earthquakes

He,

Wen,

Wang

et al. 2024

Geophysical Journal International

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SUMMARY The prominent Pamir plateau holds considerable significance in comprehending the processes of Asian continental collisional orogeny. However, due to harsh natural conditions and low seismic activity within the Pamir hinterland, our understanding of this region remains deficient. Recent major events and the accumulation of geodetic observations present a rare opportunity for us to get insights into the tectonic activities and orogenic processes occurring in this region. First, employing Sentinel-1 and Advanced Land Observation Satellite (ALOS)-2 Synthetic Aperture Radar (SAR) images, we acquire coseismic displacements associated with the most recent earthquakes in 2015 and 2023. Subsequently, we conduct the source models inversion with the constraints of surface displacements based on a finite-fault model. Our results reveal displacements ranging from −0.8 to 0.8 m for the 2015 Mw 7.2 Tajik earthquake and −0.25 to 0.25 m for the 2023 Mw 6.9 Murghob event, respectively. The optimal three-segment model for the 2015 event ruptured a fault length of 89 km with a surface rupture extending 59 km along the Sarez–Karakul fault (SKF), characterized predominantly by left-lateral strike-slip motion, with a maximum slip of 3.5 m. Meanwhile, our preferred uniform slip model suggests that the 2023 event ruptured an unmapped fault in the southern Pamir region with a strike angle of 31° and a dip angle of 76.8°. The distributed slip model indicates that the 2023 event ruptured a fault length of 32 km, resulting in an 8 km surface rupture. This event is characterized by left-lateral strike slip, with a peak slip of 2.2 m. Secondly, the Coulomb stress calculations demonstrate that the 2023 event was impeded by the 2015 event. Finally, interseismic Global Positioning System data revel a relative motion of 3.4–5.7 mm yr−1 in the N-S component and 3.2–3.8 mm yr−1 in the E-W component along the SKF in the Pamir hinterland, respectively. These N-S direction strike-slip activities and slip behaviours support an ongoing strong shear and extension in the Pamir regime, which is a response to the oblique convergence between the Indian and Eurasian plates.

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The 2015–2017 Pamir earthquake sequence: foreshocks, main shocks and aftershocks, seismotectonics, fault interaction and fluid processes

Cited by 3 publications

References 141 publications

Pore-pressure diffusion controls upper-plate aftershocks of the 2014 Iquique earthquake

Pore-pressure diffusion controls upper-plate aftershocks of the 2014 Iquique earthquake

Stress triggering and future seismic hazards implied by four large earthquakes in the Pamir from 2015 to 2023 revealed by Sentinel-1 radar interferometry

The N-S direction strike-slip activities in the Pamir hinterland under oblique convergence: the 2015 and 2023 earthquakes

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