scholarly journals COSEISMIC DEFORMATION FIELD AND FAULT SLIP DISTRIBUTION OF THE 2015 CHILE Mw8.3 EARTHQUAKE

2016 ◽  
Vol XLI-B7 ◽  
pp. 827-834
Author(s):  
Chunyan Qu ◽  
Ronghu Zuo ◽  
Xin Jian Shan ◽  
Guohong Zhang ◽  
Yingfeng Zhang ◽  
...  
Keyword(s):  
Elastic Half Space ◽  
Fault Slip ◽  
Deformation Field ◽  
Coseismic Deformation ◽  
Postseismic Deformation ◽  
Coseismic Slip ◽  
Single Plane ◽  
Rupture Length ◽  
Continental Plate ◽  
Before And After

On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m (Mw8.27)，the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation.It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate.

scholarly journals COSEISMIC DEFORMATION FIELD AND FAULT SLIP DISTRIBUTION OF THE 2015 CHILE Mw8.3 EARTHQUAKE

2016 ◽  
Vol XLI-B7 ◽  
pp. 827-834
Author(s):  
Chunyan Qu ◽  
Ronghu Zuo ◽  
Xin Jian Shan ◽  
Guohong Zhang ◽  
Yingfeng Zhang ◽  
...  
Keyword(s):  
Elastic Half Space ◽  
Fault Slip ◽  
Deformation Field ◽  
Coseismic Deformation ◽  
Postseismic Deformation ◽  
Coseismic Slip ◽  
Single Plane ◽  
Rupture Length ◽  
Continental Plate ◽  
Before And After

On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m (Mw8.27)，the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation.It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate.

scholarly journals Coseismic deformation field derived from Sentinel-1A data and slip inversion of the 2015 Chile Mw8.3 earthquake

2016 ◽  
Author(s):  
Ronghu Zuo ◽  
Chunyan Qu ◽  
XinJian Shan ◽  
Yingfeng Zhang ◽  
Guohong Zhang ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Joint Inversion ◽  
Fault Slip ◽  
Deformation Field ◽  
Seismogenic Zone ◽  
Coseismic Deformation ◽  
Dislocation Model ◽  
Coulomb Stress ◽  
Coseismic Slip ◽  
Single Plane

Abstract. We obtain the coseismic surface deformation fields caused by the Chile Mw8.3 earthquake on 16 September 2015 through analyzing Sentinel-1A/IW InSAR data from ascending and descending tracks. The results show that the main deformation field looks like a half circle convex to east with maximum coseismic displacement of about 1.33 m in descending LOS direction, 1.32 m in ascending LOS direction. Based on an elastic dislocation model in a homogeneous elastic half space, we construct a small-dip single plane fault model and invert the coseismic fault slip using ascending and descending Sentinel-1A/IW data separately and jointly. The results show that the patterns of the main slip region are similar in all datasets, but the scale of slip from ascending inversion is relatively smaller. Joint inversion can display comprehensive fault slip. The seismic moment magnitude from the joint inversion is Mw8.25, the rupture length along strike is about 340 km with a maximum slip of 8.16 m near the trench located at –31.04 N, –72.49 E, and the coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The depth where coseismic slip is near zero appears to a depth of 50 km, quantitatively indicating the down-dip limit of the seismogenic zone. From the calculated coseismic Coulomb stress change, we find aftershocks locations correlate well with the areas having increased Coulomb stress and most areas with increased Coulomb stress appeared beneath the main shock fault plane.

scholarly journals 3D Coseismic Deformation Field and Source Parameters of the 2017 Iran-Iraq Mw7.3 Earthquake Inferred from DInSAR and MAI Measurements

2019 ◽  
Vol 11 (19) ◽  
pp. 2248 ◽  
Author(s):  
Zhiheng Wang ◽  
Rui Zhang ◽  
Yuxin Liu
Keyword(s):  
Ground Deformation ◽  
Source Parameters ◽  
Field Measurements ◽  
Parameters Estimation ◽  
Deformation Field ◽  
Coseismic Deformation ◽  
United States Geological Survey ◽  
Data Sets ◽  
Coseismic Slip ◽  
Main Fault

The coseismic slip on the main fault related to the 2017 Iran-Iraq Mw7.3 earthquake has been investigated by previous studies using DInSAR (differential interferometric synthetic aperture radar) ground deformation measurements. However, DInSAR observation is not sensitive to the ground deformation in the along-track (AT) direction. Therefore, only the one-dimensional (1D) DInSAR coseismic deformation field measurements, derived in the LOS (line-of-sight) direction of radar, was applied in source parameters estimation. To further improve the accuracy of the fault slip inversion, the 3D (three-dimensional) coseismic deformation fields were reconstructed in the first place, by a combined use of the DInSAR and MAI (multiple aperture InSAR) measurements. Subsequently, the LOS and 3D deformation data sets were used as the constraint respectively, to perform a two-step inversion scheme to find an optimal geometry and slip distribution on the main fault. The comparative analysis indicated that the 3D coseismic deformation data sets improved the inversion-accuracy by 30%. Besides, the fault invention results revealed a deep dislocation on a NNW trending fault (the strike is 352.63°) extending about 60 km, along the fault dips 14.76° to the ENE. The estimated seismic moment is 8.44 × 1019 Nm (Mw7.3), which is close to the solution provided by USGS (United States Geological Survey). The slip distributed at the depth between 12 and 18 km, and the peak slip of 6.53 m appears at the depth of 14.5 km left near the epicenter. Considering the geological structure in the earthquake region and fault source-parameters, it comes to a preliminary conclusion that the ZMFF (the Zagros Mountain Front fault) should be responsible for the earthquake. In general, this paper demonstrated the superiority of using the 3D coseismic deformation fields on source parameters estimation.

Postseismic deformation of the Ms 8.1 Nepal earthquake in 2015 from GPS observations

2020 ◽  
Author(s):  
Xiaoning Su ◽  
Guojie Meng
Keyword(s):  
Temporal Distribution ◽  
Exponential Model ◽  
Deformation Field ◽  
Monte Carlo Algorithm ◽  
Coseismic Deformation ◽  
Postseismic Deformation ◽  
Model Parameters ◽  
Southern Tibet ◽  
Logarithmic Model ◽  
Deformation Models

<p>On April 25, 2015, the Nepal M<sub>S</sub> 8.1 earthquake took place in the Himalayan seismic belt on the southern margin of Tibetan Plateau. After the earthquake, the China Earthquake Administration established Immediately 13 GPS continuous stations in the southern Tibetan region. In this study, such data, the data of China’s crustal movement observation network in the southern Tibet region and the data of GPS continuous stations in Nepal are used to estimate the postseismic deformation of the GPS station. Three postseismic deformation models, i.e., a logarithmic model, an exponential model and an integrated combination, are used for fitting GPS postseismic deformation. The Markov Chain Monte Carlo algorithm, based on a Bayesian framework, is applied to invert model parameters. The results show that the integrated model for the logarithmic model and exponential model can accurately fit the postseismic deformation observed by GPS, indicating that the postseismic deformation observed by GPS may involve two different deformation mechanisms with multi-scale characteristics. Based on the analysis of the spatial-temporal distribution of the postseismic deformation field and its comparison with the coseismic deformation field, it is considered that the afterslip mainly occurs in the deep area where the coseismic rupture extends northward, while the seismic risk in the shallow area where the coseismic rupture is not broken still deserves further attention.</p>

scholarly journals Adjoint-based direct data assimilation of GNSS time series for optimizing frictional parameters and predicting postseismic deformation following the 2003 Tokachi-oki earthquake

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Masayuki Kano ◽  
Shin’ichi Miyazaki ◽  
Yoichi Ishikawa ◽  
Kazuro Hirahara
Keyword(s):  
Time Series ◽  
Data Assimilation ◽  
Evaluation Method ◽  
Temporal Evolution ◽  
Recovery Process ◽  
Postseismic Deformation ◽  
Coseismic Slip ◽  
Megathrust Earthquakes ◽  
Spatio Temporal ◽  
Gnss Time Series

Abstract Postseismic Global Navigation Satellite System (GNSS) time series followed by megathrust earthquakes can be interpreted as a result of afterslip on the plate interface, especially in its early phase. Afterslip is a stress release process accumulated by adjacent coseismic slip and can be considered a recovery process for future events during earthquake cycles. Spatio-temporal evolution of afterslip often triggers subsequent earthquakes through stress perturbation. Therefore, it is important to quantitatively capture the spatio-temporal evolution of afterslip and related postseismic crustal deformation and to predict their future evolution with a physics-based simulation. We developed an adjoint data assimilation method, which directly assimilates GNSS time series into a physics-based model to optimize the frictional parameters that control the slip behavior on the fault. The developed method was validated with synthetic data. Through the optimization of frictional parameters, the spatial distributions of afterslip could roughly (but not in detail) be reproduced if the observation noise was included. The optimization of frictional parameters reproduced not only the postseismic displacements used for the assimilation, but also improved the prediction skill of the following time series. Then, we applied the developed method to the observed GNSS time series for the first 15 days following the 2003 Tokachi-oki earthquake. The frictional parameters in the afterslip regions were optimized to A–B ~ O(10 kPa), A ~ O(100 kPa), and L ~ O(10 mm). A large afterslip is inferred on the shallower side of the coseismic slip area. The optimized frictional parameters quantitatively predicted the postseismic GNSS time series for the following 15 days. These characteristics can also be detected if the simulation variables can be simultaneously optimized. The developed data assimilation method, which can be directly applied to GNSS time series following megathrust earthquakes, is an effective quantitative evaluation method for assessing risks of subsequent earthquakes and for monitoring the recovery process of megathrust earthquakes.

Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan

2020 ◽  
Vol 224 (1) ◽  
pp. 416-434
Author(s):  
Dezheng Zhao ◽  
Chunyan Qu ◽  
Xinjian Shan ◽  
Roland Bürgmann ◽  
Wenyu Gong ◽  
...  
Keyword(s):  
Main Shock ◽  
Near Field ◽  
Active Faults ◽  
Fault Model ◽  
Body Waves ◽  
Coseismic Deformation ◽  
Coseismic Slip ◽  
Coulomb Stress Changes ◽  
Seismic Displacement ◽  
Stress Changes

SUMMARY We investigate the coseismic and post-seismic deformation due to the 6 February 2018 Mw 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults.

Coseismic slip propagation on the Tohoku plate boundary fault facilitated by slip-dependent weakening during slow fault slip

2017 ◽  
Vol 44 (17) ◽  
pp. 8749-8756 ◽  
Author(s):  
Yoshihiro Ito ◽  
Matt J. Ikari ◽  
Kohtaro Ujiie ◽  
Achim Kopf
Keyword(s):  
Plate Boundary ◽  
Fault Slip ◽  
Coseismic Slip ◽  
Boundary Fault
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