New insight into the 24 January 2020, Mw 6.8 Elazığ earthquake (Turkey): An evidence for rupture-parallel pull-apart basin activation along the East Anatolian Fault Zone constrained by Geodetic and Seismological data

2021 ◽  
Vol 64 (4) ◽  
pp. SE439
Author(s):  
T Serkan Irmak ◽  
Mustafa Toker ◽  
Evrim Yavuz ◽  
Erman Şentürk ◽  
Muhammed Ali Güvenaltın
Keyword(s):  
Fault Zone ◽  
Surface Deformation ◽  
Waveform Inversion ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
Deformation Pattern ◽  
Pull Apart Basin ◽  
Insight Into ◽  
East Anatolian Fault Zone ◽  
East Anatolian Fault

In this study, we investigated the main features of the causative fault of the 24 January 2020, Mw 6.8 Elazığ earthquake (Turkey) using seismological and geodetic data sets to provide new insight into the East Anatolian Fault Zone (EAFZ). We first constrained the co-seismic surface deformation and the rupture geometry of the causative fault segment using Interferometric Synthetic Aperture Radar (InSAR) interferograms (Sentinel-1A/B satellites) and teleseismic waveform inversion, respectively. Also, we determined the centroid moment tensor (CMT) solutions of focal mechanisms of the 27 aftershocks using the regional waveform inversion method. Finally, we evaluated the co-seismic slip distribution and the CMT solutions of the causative fault as well as of adjacent segments using the 27 focal solutions of the aftershocks, superimposed on the surface deformation pattern. The CMT solution of the 24 January 2020Elazığ earthquake reveals a pure strike-slip focal mechanism, consistent with the structural pattern and left-lateral motion of the EAFZ. The rupture process of the Elazığ event indicated that the rupture is started at 12 km around the hypocenter, and then propagated bilaterally along the NE-SW but mainly toward the southwest. The rupture slip has initially propagated toward the southwest (first 10 s) and northeast (4 s), and again toward the southwest (9 s). Maximum displacement is calculated as 1.3 m about 20 km southwest of the hypocenter at 6 km depth (centroid depth). The rupture stopped to down-dip around 20 km depth toward the southwest. The distribution of the slip vectors indicates that the rupture continued mostly through a normal oblique movement. Most of the moment release was released SW of the hypocenter and the rupture reached up to around 50 km. The focal mechanisms of analyzed 27 aftershocks show strike-slip, but mostly normal and normal oblique-slip faulting with an orientation of the tensional axes (NNE-SSW), indicating a normal oblique-slip, “transtensional” stress regime, parallel-subparallel to the strike of the EAFZ, consistent with SW-rupture directivity and co- seismic deformation pattern. Finally, based on the co-seismic surface deformation compatible with the distributional pattern of normal focal solutions, normal and normal oblique-slip focals of the aftershocks evidence the rupture-parallel pull-apart basin activation as a segment boundary of the left-lateral strike-slip movement of the EAFZ.

Source Process of the 24 January 2020 Mw 6.7 East Anatolian Fault Zone, Turkey, Earthquake

2020 ◽  
Vol 91 (6) ◽  
pp. 3120-3128
Author(s):  
Jiao Xu ◽  
Chengli Liu ◽  
Xiong Xiong
Keyword(s):  
Fault Zone ◽  
Fault Plane ◽  
Historical Earthquakes ◽  
Source Process ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
Coseismic Slip ◽  
Insight Into ◽  
East Anatolian Fault Zone ◽  
East Anatolian Fault

Abstract The 24 January 2020 Mw 6.7 earthquake in eastern Turkey was due to the reactivation of the strike-slip faulting between the Arabian and Anatolian plates. To gain insight into the source regime and its relationship with historical earthquakes, we determined the coseismic slip distribution of this event by joint analyses of Interferometric Synthetic Aperture Radar and teleseismic observations. Inversion results indicate that the main rupture asperity occurred in the southwest of the epicenter with a maximum slip of ∼1.9  m, showing a bilateral source process with an average rupture velocity of ∼1.6  km/s, and small slip extended to the surface near the epicenter. The estimated seismic moment is 1.4×1019  N·m, associated with a ∼50  km long and ∼15  km wide fault plane. The aftershocks distribution is obviously complementary with the coseismic rupture zone. That is, the majority of aftershocks clustered in the transitional regions from the large to small slip areas. The 2020 earthquake only ruptured part of the locked zone and could increase the seismic activity in the East Anatolian fault zone during the interseismic phase. Two verified seismic gaps remain unbroken and hazardous.

Evidence of Fault Immaturity from Shallow Slip Deficit and Lack of Postseismic Deformation of the 2017 Mw 6.5 Jiuzhaigou Earthquake

2020 ◽  
Vol 110 (1) ◽  
pp. 154-165 ◽  
Author(s):  
Yuexin Li ◽  
Roland Bürgmann ◽  
Bin Zhao
Keyword(s):  
Wenchuan Earthquake ◽  
Fault Zone ◽  
Surface Deformation ◽  
Strike Slip ◽  
Stress Change ◽  
Depth Interval ◽  
Postseismic Deformation ◽  
Jiuzhaigou Earthquake ◽  
2008 Wenchuan Earthquake ◽  
Slip Deficit

ABSTRACT The Mw 6.5 Jiuzhaigou earthquake occurred on 8 August 2017 36 km west-southwest of Yongle, Sichuan, China. We use both ascending and descending Interferometric Synthetic Aperture Radar (InSAR) data from Sentinel-1 and coseismic offsets of four Global Positioning System sites to obtain the coseismic surface deformation field and invert for the fault geometry and slip distribution. Most slip of the left-lateral strike-slip earthquake occurred in the 3–10 km depth interval with a maximum slip of about 1 m and a large shallow slip deficit (SSD). An eight-month InSAR time-series analysis documents a lack of resolvable postseismic deformation, and inversions for the distribution of postseismic slip demonstrate the lack of shallow afterslip. We argue that the observations of a pronounced SSD and no early afterslip of the Jiuzhaigou earthquake are indicative of an immature fault and that all incipient young strike-slip faults likely feature a SSD. We would expect a complex rupture geometry with distributed coseismic failure in the uppermost part of the brittle crust during the fault-zone development. As faults mature, they straighten out, develop a localized fault-zone core, and the SSD diminishes. By calculating the static Coulomb stress change and nine-year viscoelastic stress change caused by the Wenchuan earthquake, we also show that the 2008 Wenchuan earthquake did not significantly affect the time of occurrence of the 2017 Jiuzhaigou earthquake.

scholarly journals Rupture kinematics of 2020 January 24 Mw 6.7 Doğanyol-Sivrice, Turkey earthquake on the East Anatolian Fault Zone imaged by space geodesy

2020 ◽  
Vol 223 (2) ◽  
pp. 862-874 ◽  
Author(s):  
Diego Melgar ◽  
Athanassios Ganas ◽  
Tuncay Taymaz ◽  
Sotiris Valkaniotis ◽  
Brendan W Crowell ◽  
...  
Keyword(s):  
Fault Zone ◽  
Satellite System ◽  
High Rate ◽  
Slip Model ◽  
Slip Region ◽  
Global Navigation Satellite ◽  
Rupture Kinematics ◽  
Source Duration ◽  
East Anatolian Fault Zone ◽  
East Anatolian Fault

SUMMARY Here, we present the results of a kinematic slip model of the 2020 Mw 6.7 Doğanyol-Sivrice, Turkey Earthquake, the most important event in the last 50 yr on the East Anatolian Fault Zone. Our slip model is constrained by two Sentinel-1 interferograms and by 5 three-component high-rate GNSS (Global Navigation Satellite System) recordings close to the earthquake source. We find that most of the slip occurs predominantly in three regions, two of them at between 2 and 10 km depth and a deeper slip region extending down to 20 km depth. We also relocate the first two weeks of aftershocks and find a distribution of events that agrees with these slip features. The HR-GNSS recordings suggest a predominantly unilateral rupture with the effects of a directivity pulse clearly seen in the waveforms and in the measure peak ground velocities. The slip model supports rupture propagation from northeast to southwest at a relatively slow speed of 2.2 km s−1 and a total source duration of ∼20 s. In the absence of near-source seismic stations, space geodetic data provide the best constraint on the spatial distribution of slip and on its time evolution.

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