scholarly journals The 29 March 2017 Yuzhno-Ozernovskoe Kamchatka Earthquake: Fault Activity in An Extension of the East Kamchatka Fault Zone as Constrained by InSAR Observations

2020 ◽  
Vol 110 (3) ◽  
pp. 1101-1114
Author(s):  
Magdalena S. Vassileva ◽  
Mahdi Motagh ◽  
Thomas R. Walter ◽  
Hans-Ulrich Wetzel ◽  
Sergey L. Senyukov
Keyword(s):  
Synthetic Aperture Radar ◽  
Fault Zone ◽  
Subduction Zones ◽  
Synthetic Aperture ◽  
Fault System ◽  
Coseismic Deformation ◽  
Reverse Fault ◽  
Nonlinear Inversion ◽  
Fault Geometry ◽  
Aperture Radar

ABSTRACT Recent earthquakes off the northeastern Kamchatka coast reveal that this region is seismically active, although details of the locations and complexity of the fault system are lacking. The northern part of Kamchatka has poor coverage by permanent seismic stations and ground geodetic instruments. Here, we exploit the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique to characterize the fault geometry and kinematics associated with the 29 March 2017 Mw 6.6 Yuzhno-Ozernovskoe earthquake. The aim is to contribute to identifying the active fault branches and to better understanding the complex tectonic regime in this region using the DInSAR technique, which has never before been applied to the analysis of coseismic offsets in Kamchatka. We produced coseismic deformation maps using Advanced Land Observation Satellite-2 ascending and descending and Sentinel-1A descending Synthetic Aperture Radar (SAR) scenes and detected a predominant uplift up to 20 cm and a westward motion of approximately 7 cm near the shoreline. We jointly inverted the three geodetic datasets using elastic half-space fault modeling to retrieve source geometry and fault kinematics. The best-fit solution for the nonlinear inversion suggests a north–west-dipping oblique reverse fault with right-lateral rupture. The model fault geometry is not only generally consistent with the seismic data but also reveals that a hitherto unknown fault was ruptured. The identified fault structure is interpreted as the northern extension of the east Kamchatka fault zone, implying that the region is more complex than previously thought. Important implications arise for the presence of unknown faults at the edges of subduction zones that can generate earthquakes with magnitudes greater than Mw 6.

Assessment of the Seismic Hazards of the Marikina Valley Fault from 2019 Mw 6.1 Castillejos Earthquake and Historical Events

2021 ◽  
Author(s):  
Ying-Hui Yang ◽  
Min-Chien Tsai ◽  
Jyr-Ching Hu ◽  
Qiang Chen ◽  
Mario Aurelio ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Fault System ◽  
Seismogenic Zone ◽  
Coseismic Deformation ◽  
Interferometric Synthetic Aperture Radar ◽  
Sar Images ◽  
Strong Earthquakes ◽  
Coulomb Failure ◽  
Aperture Radar

Abstract The 2019 Mw 6.1 Castillejos earthquake occurred in the Zambales range of the central Luzon Island in Philippines. No active fault was reported around the seismogenic zone according to previous investigations. This earthquake draws attention for assessment in seismic risk along the Marikina Valley fault system (MVFS) near the Manila dense metropolitan population. The Coulomb failure stress (CFS) change on the MVFS is estimated by the coseismic faulting model derived from the inversion of coseismic deformation field observed from the Differential Interferometric Synthetic Aperture Radar using both the Advanced Land Observing Satellite-2 and Sentinel-1 Synthetic Aperture Radar (SAR) images. The predicted CFS change is less than 0.5 kPa that implies insignificant Coulomb stress accumulation on the MVFS after the Mw 6.1 Castillejos event. However, the recorded 14 moderate and strong earthquakes in and around the Luzon islands caused significant CFS drop on the MVFS. This might delay the occurrence of the earthquake for 0.2–50 yr on the MVFS.

scholarly journals Source Characteristics of the 28 September 2018 Mw 7.4 Palu, Indonesia, Earthquake Derived from the Advanced Land Observation Satellite 2 Data

2019 ◽  
Vol 11 (17) ◽  
pp. 1999 ◽  
Author(s):  
Yongzhe Wang ◽  
Wanpeng Feng ◽  
Kun Chen ◽  
Sergey Samsonov
Keyword(s):  
Synthetic Aperture Radar ◽  
Main Shock ◽  
Least Square ◽  
Synthetic Aperture ◽  
Coseismic Deformation ◽  
The South ◽  
Land Observation Satellite ◽  
Step Over ◽  
Central Sulawesi ◽  
Aperture Radar

On 28 September 2018, an Mw 7.4 earthquake, followed by a tsunami, struck central Sulawesi, Indonesia. It resulted in serious damage to central Sulawesi, especially in the Palu area. Two descending paths of the Advanced Land Observation Satellite 2 (ALOS-2) synthetic aperture radar (SAR) data were processed with interferometric synthetic aperture radar (InSAR) and pixel tracking techniques to image the coseismic deformation produced by the earthquake. The deformation measurement was used to determine the fault geometry and the coseismic distributed slip model with a constrained least square algorithm based on the homogeneous elastic half-space model. We divided the fault into four segments (named AS, BS, CS and DS, from the north to the south) in the inversion. The BS segment was almost parallel to the DS segment, the CS segment linked the BS and DS segments, and these three fault segments formed a fault step-over system. The Coulomb failure stress (CFS) change on the causative fault was also calculated. Results show that the maximum SAR line-of-sight (LOS) and horizontal deformation were −1.8 m and 3.6 m, respectively. The earthquake ruptured a 210-km-long fault with variable strike angles. The ruptured pattern of the causative fault is mainly a sinistral slip. Almost-pure normal characteristics could be identified along the fault segment across the Palu bay, which could be one of the factors resulting in the tsunami. The main slip area was concentrated at the depths of 0–20 km, and the maximum slip was 3.9 m. The estimated geodetic moment of the earthquake was 1.4 × 1020 Nm, equivalent to an earthquake of Mw 7.4. The CFS results demonstrate that the fault step-over of 5.3 km width did not terminate the rupture propagation of the main shock to the south. Two M>6 earthquakes (the 23 January 2005 and the 18 August 2012) decreased CFS along CS segment and the middle part of DS segment of the 2018 main shock. This implies that the stress release during the previous two earthquakes may have played a vital role in controlling the coseismic slip pattern of the 2018 earthquake.

scholarly journals Multi-Sensor Geodetic Observations and Modeling of the 2017 Mw 6.3 Jinghe Earthquake

2019 ◽  
Vol 11 (18) ◽  
pp. 2157 ◽  
Author(s):  
Gong ◽  
Zhang ◽  
Li ◽  
Wen ◽  
Zhao ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Coseismic Deformation ◽  
Seismogenic Fault ◽  
Geodetic Inversion ◽  
Displacement Maps ◽  
Tian Shan Mountains ◽  
Sar Imagery ◽  
Tian Shan ◽  
Aperture Radar

The Mw 6.3 Jinghe earthquake struck Xingjiang Province, China, on 8 August 2017 (05:15:04 UTC); the epicenter was near the Kusongmuxieke Piedmont Fault (KPF) of the northern Tian Shan Mountains. We used multi-source and multi-track satellite Synthetic Aperture Radar (SAR) imagery and Interferometric SAR (InSAR) techniques to reconstruct the coseismic displacement field from different line-of-sight geometries. To reduce the phase artifacts, we employed multi-temporal scenes acquired by Sentinel-1, and reconstructed the coseismic deformation through a temporal averaging strategy. Together with a single interferometric pair obtained using the Phased Array type L-band Synthetic Aperture Radar 2 (PALSAR2) sensor aboard the Advanced Land Observing Satellite 2 (ALOS2), we obtained five displacement maps with slightly different viewing geometries; all of which were used to constrain a geodetic inversion to retrieve the fault geometry parameters and slip distribution. Based on the focal mechanism and regional geology, we constructed multiple fault models that differ in dip direction (south and north dipping), and various striking angles. Both models fit the InSAR displacement maps, but have slip distributions of different depths. The slip depth of the south dipping model, with a dip of ~42°, is the most consistent with the relocated earthquake sequence and regional geological structure. Through the geodetic inversion, the maximum slip (0.25 m) occurred at 14.05 km and the associated rake was 89.56°. The result implies that the seismogenic fault is a blind thrust fault north of KPF (towards the foreland). Considering the relative locations of the suggested blind fault, the KPF, and the continuing north to south (N–S) shortening of the Tian Shan Mountains, this fault could be formed by the northward propagation of the regional fold-thrust belt.

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