Coseismic Slip Model of the 2018 Mw 7.9 Gulf of Alaska Earthquake and Its Seismic Hazard Implications

2018 ◽  
Vol 90 (2A) ◽  
pp. 642-648 ◽  
Author(s):  
Bin Zhao ◽  
Yujie Qi ◽  
Dongzhen Wang ◽  
Jiansheng Yu ◽  
Qi Li ◽  
...  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinji Yamashita ◽  
Yuji Yagi ◽  
Ryo Okuwaki ◽  
Kousuke Shimizu ◽  
Ryoichiro Agata ◽  
...  

AbstractWe developed a flexible finite-fault inversion method for teleseismic P waveforms to obtain a detailed rupture process of a complex multiple-fault earthquake. We estimate the distribution of potency-rate density tensors on an assumed model plane to clarify rupture evolution processes, including variations of fault geometry. We applied our method to the 23 January 2018 Gulf of Alaska earthquake by representing slip on a projected horizontal model plane at a depth of 33.6 km to fit the distribution of aftershocks occurring within one week of the mainshock. The obtained source model, which successfully explained the complex teleseismic P waveforms, shows that the 2018 earthquake ruptured a conjugate system of N-S and E-W faults. The spatiotemporal rupture evolution indicates irregular rupture behavior involving a multiple-shock sequence, which is likely associated with discontinuities in the fault geometry that originated from E-W sea-floor fracture zones and N-S plate-bending faults.


2021 ◽  
Author(s):  
Abeer Al-Ashkar ◽  
Antoine Schlupp ◽  
Matthieu Ferry ◽  
Ulziibat Munkhuu

Abstract. We present new constraints from tectonic geomorphology and paleoseismology along the newly discovered Sharkhai fault near the capital city of Mongolia. Detailed observations from high resolution Pleiades satellite images and field investigations allowed us to map the fault in detail, describe its geometry and segmentation, characterize its kinematics, and document its recent activity and seismic behavior (cumulative displacements and paleoseismicity). The Sharkhai fault displays a surface length of ~40 km with a slightly arcuate geometry, and a strike ranging from N42° E to N72° E. It affects numerous drainages that show left-lateral cumulative displacements reaching 57 m. Paleoseismic investigations document the faulting and deposition record for the last ~3000 yr and reveal that the penultimate earthquake (PE) occurred between 1515 ± 90 BC and 945 ± 110 BC and the most recent event (MRE) occurred after 860 ± 85 AD. The resulting time interval of 2080 ± 470 years is the first constraint on the Sharkhai fault for large earthquakes. On the basis of our mapping of the surface rupture and the resulting segmentation analysis, we propose two possible scenarios for large earthquakes with likely magnitudes between 6.4 ± 0.2 and 7.1 ± 0.2. Furthermore, we apply scaling laws to infer coseismic slip values and derive preliminary estimates of long-term slip rates between 0.2 ± 0.2 and 1.0 ± 0.5 mm/y. Finally, we propose that these original observations and results from a newly discovered fault should be taken into account for the seismic hazard assessment for the city of Ulaanbaatar and help build a comprehensive model of active faults in that region.


2021 ◽  
Vol 267 ◽  
pp. 112733
Author(s):  
Bochen Zhang ◽  
Xiaoli Ding ◽  
Falk Amelung ◽  
Chisheng Wang ◽  
Wenbin Xu ◽  
...  

2020 ◽  
Vol 298 ◽  
pp. 106336
Author(s):  
Stefano Santini ◽  
Michele Dragoni

2016 ◽  
Author(s):  
Putra Maulida ◽  
Irwan Meilano ◽  
Endra Gunawan ◽  
Joni Efendi

2021 ◽  
Author(s):  
Shinji Yamashita ◽  
Yuji Yagi ◽  
Ryo Okuwaki ◽  
Kousuke Shimizu ◽  
Ryoichiro Agata ◽  
...  

2020 ◽  
Vol 92 (1) ◽  
pp. 127-139
Author(s):  
Xin Lin ◽  
Jinlai Hao ◽  
Dun Wang ◽  
Risheng Chu ◽  
Xiangfang Zeng ◽  
...  

Abstract On 24 January 2020 (UTC), a destructive Mw 6.7 earthquake struck the east Anatolian fault of eastern Turkey after a series of foreshocks, causing many casualties and significant property damage. In this study, the rupture process of this earthquake is investigated with teleseismic broadband body-wave and surface-wave records. Results indicate that this earthquake is a left-lateral strike-slip event, and the rupture extends mainly to south. The main slip patch spreads ∼30  km along strike in the shallow above 14 km with a peak slip of ∼1.2  m, and the total seismic moment is 1.69×1019  N·m. The east–west component of horizontal surface displacement predicted with our slip model ranges from ∼0.4 to −0.3  m. The predicted displacements are consistent with the observed ones obtained from satellite images. We relocate 459 foreshocks and early aftershocks to explore the relationship between foreshock and aftershock sequences and coseismic slip. It is noted that there is an anticorrelation relationship between the distributions of early aftershocks and the coseismic slip. The strain energy in the large slip patch may have been sufficiently released by the mainshock; therefore, fewer early aftershocks occurred in that patch. Although we note a similar pattern between the relocated foreshock and coseismic slip, and a migration of foreshock, our dataset may not well resolve the correlation and migration due to the incomplete relocation foreshock catalog. Based on the slip model, we calculate the coulomb stress changes on the surrounding faults caused by the mainshock. The results reveal that the mainshock promoted stress accumulation on the northern and southern ends of the Elazig–Matalya segment and may reactivate the locked fault segment, leading to a high seismic risk in these regions. Although this earthquake does not significantly increase the coulomb stress change, the seismic risk of the Matalya–Kahraman Maras–Antakya segment should draw attention.


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