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1. Detailed spatiotemporal evolution of microseismicity and repeating earthquakes following the 2012 Mw 7.6 Nicoya earthquake: Nicoya Aftershock and Repeating Events

   https://doi.org/10.1002/2016JB013632  

   Yao, Dongdong ; Walter, Jacob I. ; Meng, Xiaofeng ; Hobbs, Tiegan E. ; Peng, Zhigang ; Newman, Andrew V. ; Schwartz, Susan Y. ; Protti, Marino ( January 2017 , Journal of Geophysical Research: Solid Earth)
2. Repeating Earthquakes at the Edge of the Afterslip of the 2016 Ecuadorian M W 7.8 Pedernales Earthquake

   https://doi.org/10.1029/2021JB021746  

   Chalumeau, Caroline ; Agurto‐Detzel, Hans ; De Barros, Louis ; Charvis, Philippe ; Galve, Audrey ; Rietbrock, Andreas ; Alvarado, Alexandra ; Hernandez, Stephen ; Beck, Susan ; Font, Yvonne ; et al ( May 2021 , Journal of Geophysical Research: Solid Earth)

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3. Postseismic Deformation Following the 2015 M w 7.8 Gorkha (Nepal) Earthquake: New GPS Data, Kinematic and Dynamic Models, and the Roles of Afterslip and Viscoelastic Relaxation

   https://doi.org/10.1029/2020JB019852  

   Liu‐Zeng, J. ; Zhang, Z. ; Rollins, C. ; Gualandi, A. ; Avouac, J. ‐P. ; Shi, H. ; Wang, P. ; Chen, W. ; Zhang, R. ; Zhang, P. ; et al ( September 2020 , Journal of Geophysical Research: Solid Earth)

   We report Global Positioning System (GPS) measurements of postseismic deformation following the 2015 M_w7.8 Gorkha (Nepal) earthquake, including previously unpublished data from 13 continuous GPS stations installed in southern Tibet shortly after the earthquake. We use variational Bayesian Independent Component Analysis (vbICA) to extract the signal of postseismic deformation from the GPS time series, revealing a broad displacement field extending >150 km northward from the rupture. Kinematic inversions and dynamic forward models show that these displacements could have been produced solely by afterslip on the Main Himalayan Thrust (MHT) but would require a broad distribution of afterslip extending similarly far north. This would require the constitutive parameter(a − b)σto decrease northward on the MHT to ≤0.05 MPa (an extreme sensitivity of creep rate to stress change) and seems unlikely in light of the low interseismic coupling and high midcrustal temperatures beneath southern Tibet. We conclude that the northward reach of postseismic deformation more likely results from distributed viscoelastic relaxation, possibly in a midcrustal shear zone extending northward from the seismogenic MHT. Assuming a shear zone 5–20 km thick, we estimate an effective shear‐zone viscosity of ~3·10¹⁶–3·10¹⁷ Pa·s over the first 1.12 postseismic years. Near‐field deformation can be more plausibly explained by afterslip itself and implies(a − b)σ ~ 0.5–1 MPa, consistent with other afterslip studies. This near‐field afterslip by itself would have re‐increased the Coulomb stress by ≥0.05 MPa over >30% of the Gorkha rupture zone in the first postseismic year, and deformation further north would have compounded this reloading.

    

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4. The July 2019 Ridgecrest, California, Earthquake Sequence Recorded by Creepmeters: Negligible Epicentral Afterslip and Prolonged Triggered Slip at Teleseismic Distances

   https://doi.org/10.1785/0220190293  

   Bilham, Roger ; Castillo, Bryan ( January 2020 , Seismological Research Letters)

   Abstract We report sequential triggered slip at 271–384 km distances on the San Andreas, Superstition Hills, and Imperial faults with an apparent travel-time speed of 2.2 ± 0.1  km/s, following the passage of surface waves from the 4 July 2019 (17:33:49 UTC) Mw 6.4 and 6 July 2019 (03:19:53 UTC) Mw 7.1 Ridgecrest earthquakes. Slip on remote faults was not triggered instantaneously but developed over several minutes, increasing in duration with distance. Maximum slip amplitudes varied from 10  μm to 5 mm within minutes of slip nucleation, but on the southernmost San Andreas fault slip continued for two months and was followed on 16 September 2019 by a swarm of microearthquakes (Mw≤3.8) near Bombay Beach. These observations add to a growing body of evidence that fault creep may result in delayed triggered seismicity. Displacements across surface faults in the southern epicentral region and on the Garlock fault in the months following the Ridgecrest earthquakes were negligible (<1.1  mm), and they are interpreted to characterize surface strain adjustments in the epicentral region, rather than to result from discrete slip on surface faults. 

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5. Afterslip on Conjugate Faults of the 2020 Mw 6.3 Nima Earthquake in the Central Tibetan Plateau: Evidence from InSAR Measurements

   https://doi.org/10.1785/0120220247  

   Hong, Shunying ; Liu, Mian ; Zhou, Xin ; Meng, Guojie ; Dong, Yanfang ( May 2023 , Bulletin of the Seismological Society of America)

   ABSTRACT Afterslip could help to reveal seismogenic fault structure. The 2020 Mw 6.3 Nima earthquake happened in a pull-apart basin within the Qiangtang block, central Tibetan plateau. Previous studies have explained the coseismic and early (<6 mo) postseismic deformation by rupture and afterslip on a normal fault bounding the western side of the basin. Here, we resolved the 19-month Interferometric Synthetic Aperture Radar-measured sequences of postseismic displacements that revealed a second postseismic displacement center ~12 km to the east of the main fault. Fitting the postseismic displacement requires afterslip on both the main fault and an antithetic fault that probably forms a y-shaped pair of conjugate faults in a negative flower structure. Stress-driven afterslip models suggest that the required afterslip on the antithetic fault could be triggered by coseismic rupture of the main fault or by a simultaneous rupture on the antithetic fault. The afterslip on both faults occurred mainly up-dip to the coseismic slip and has released moment ~15%–19% of that by the coseismic rupture. These results provide insights into active extension in the central Tibetan plateau and highlight the complex nature of fault rupture and afterslip. 

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