scholarly journals Ground-Penetrating Radar Imaging of Near-Surface Deformation along the Songino Active Fault in the Vicinity of Ulaanbaatar, Mongolia

2021 ◽  
Vol 11 (17) ◽  
pp. 8242
Author(s):  
Maksim Bano ◽  
Nyambayar Tsend-Ayush ◽  
Antoine Schlupp ◽  
Ulziibat Munkhuu
Keyword(s):  
Surface Deformation ◽  
Active Faults ◽  
Deformation Mode ◽  
Capital City ◽  
Coseismic Deformation ◽  
Surface Geometry ◽  
Differential Gps ◽  
Essential Information ◽  
Near Surface ◽  
Ground Penetrating

The seismic activity observed in the vicinity of Ulaanbaatar (UB) capital city has been increased since 2005. Several active faults have been identified in the UB area. Most of the Mongolian population is concentrated around UB (1.5 million), which is the main political and economic center of the country. Hence, the study of seismic hazard is of first importance for the country. In this paper, we present the GPR results obtained on the Songino fault which is situated at 20 km west-southwest of UB at the northeast tip of Khustai fault. The combination of the morphotectonic, GPR and paleoseismological investigations brings essential information for seismic hazards assessments. The 2D GPR profiles are measured by using 250 and 500 MHz antennae and the topography using a differential GPS. An appropriate processing of the GPR data, including the topographic migration, allows us to bring out indirect characteristics of these faults. The objective is to identify near-surface geometry and coseismic deformation along the mapped fault. The 250 MHz GPR images of the Songino fault show the evolution of the sub-surface deformation mode induced by the arched geometry of the Songino fault. We observe a clear compressive structure at its NW section, strike slip at its central section and extensive structure in its SE part.

Near-surface structure revealed by ground penetrating radar profiling across an inland active fault ruptured one month after the 2011 Tohoku-oki earthquake, southern Fukushima, NE Japan

2020 ◽  
Author(s):  
Haruo Kimura ◽  
Hiroyuki Tsutsumi ◽  
Naotsugu Higashimaru ◽  
Kaoru Taniguchi
Keyword(s):  
Surface Structure ◽  
Ground Penetrating Radar ◽  
Active Faults ◽  
Vertical Displacement ◽  
Coseismic Deformation ◽  
Near Surface ◽  
The North ◽  
Angle Measurements ◽  
Surface Ruptures ◽  
Ground Penetrating

<p>  The 11 March 2011 Tohoku-oki earthquake (Mw = 9.0) ruptured a 500 km-long and 200 km-wide thrust of convergent boundary between the North American and Pacific plates. The earthquake caused crustal stress field changes and triggered widespread seismic activity in the northeast Japan. The southern Fukushima area was struck by many earthquakes. The largest normal faulting (Mw = 6.6) in the area ruptured the NW-trending Yunodake fault and the NNW-trending Itozawa fault on 11 April 2011. The coseismic surface ruptures were observed along active and presumed active faults identified previously. To investigate the near-surface structure of the Itozawa fault, we conducted ground penetrating radar (GPR) profiling across the fault, and we carried out two drilling surveys in hanging and foot walls of the fault. The survey line, which length was about 50 m, was located nearby a trench site (Toda and Tsutsumi, 2013). The GPR data were collected by common-offset modes using 50, 100, and 200 MHz GPR systems (pulseEKKO PRO made by Sensors and Software Inc.), and the station spacing was 0.05 m. Furthermore, we carried out wide-angle measurements, and acquired common mid-point (CMP) ensembles at the both sides of the surface rupture to estimate the electromagnetic wave velocity used in the depth conversion of the GPR sections. The GPR sections after careful data processing show detailed structure above a depth of about 10 m. We interpreted some horizons as an event showing coseismic deformation on 11 April 2011, the past seismic event reported by Toda and Tsutsumi (2013), that informing the former event, respectively. The horizons explain accumulation of vertical displacement on the Itozawa fault.</p><p> </p>

scholarly journals Fault source investigation of the 6 December 2016 MwMw 6.5 Pidie Jaya, Indonesia, earthquake based on GPS and its implications of the geological survey result

2020 ◽  
Vol 14 (4) ◽  
pp. 405-412
Author(s):  
Endra Gunawan ◽  
Takuya Nishimura ◽  
Susilo Susilo ◽  
Sri Widiyantoro ◽  
Nanang T. Puspito ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Source Parameters ◽  
Secondary Effects ◽  
Near Surface ◽  
Morphological Attributes ◽  
Ground Shaking ◽  
The North ◽  
Coulomb Failure ◽  
North And South ◽  
Fault Source

AbstractOn 6 December 2016 at 22:03 UTC, a devastating magnitude 6-class strike-slip earthquake occurred along an unidentified and unmapped fault in Pidie Jaya, northern Sumatra. We analysed the possible fault using continuous Global Positioning System (GPS) observation available in the region. In our investigation, we searched for the fault source parameters of the north- and south-dipping left-lateral faults and the west- and east-dipping right-lateral faults. We identified that the fault responsible for the earthquake was located offshore, with a southwest-northeast direction. We also computed the Coulomb failure stress and compared the result with the distribution of the aftershocks. In this study, we demonstrated that the result of the geological field survey conducted soon after the mainshock was attributed to the secondary effects of ground shaking and near-surface deformation, and not surface faulting. The newly identified offshore fault proposed by this study calls for further investigation of the corresponding submarine morphological attributes in this particular region.

scholarly journals Elucidating the Onset of Plasticity in Sliding Contacts Using Differential Computational Orientation Tomography

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
S. J. Eder ◽  
P. G. Grützmacher ◽  
M. Rodríguez Ripoll ◽  
J. F. Belak
Keyword(s):  
Grain Boundary ◽  
Large Scale ◽  
Surface Deformation ◽  
Boundary Migration ◽  
Material Design ◽  
Lattice Rotation ◽  
Time Resolved ◽  
Near Surface ◽  
Color Saturation ◽  
Dynamics Simulations

Abstract Depending on the mechanical and thermal energy introduced to a dry sliding interface, the near-surface regions of the mated bodies may undergo plastic deformation. In this work, we use large-scale molecular dynamics simulations to generate “differential computational orientation tomographs” (dCOT) and thus highlight changes to the microstructure near tribological FCC alloy surfaces, allowing us to detect subtle differences in lattice orientation and small distances in grain boundary migration. The analysis approach compares computationally generated orientation tomographs with their undeformed counterparts via a simple image analysis filter. We use our visualization method to discuss the acting microstructural mechanisms in a load- and time-resolved fashion, focusing on sliding conditions that lead to twinning, partial lattice rotation, and grain boundary-dominated processes. Extracting and laterally averaging the color saturation value of the generated tomographs allows us to produce quantitative time- and depth-resolved maps that give a good overview of the progress and severity of near-surface deformation. Corresponding maps of the lateral standard deviation in the color saturation show evidence of homogenization processes occurring in the tribologically loaded microstructure, frequently leading to the formation of a well-defined separation between deformed and undeformed regions. When integrated into a computational materials engineering framework, our approach could help optimize material design for tribological and other deformation problems. Graphic Abstract .

Imaging the internal structure of trunks via multiscale phase inversion of ground-penetrating radar data

2021 ◽  
pp. 1-53
Author(s):  
Lei Fu ◽  
Lanbo Liu
Keyword(s):  
Dielectric Constant ◽  
Internal Structure ◽  
Ground Penetrating Radar ◽  
Phase Inversion ◽  
Multiscale Approach ◽  
White Oak ◽  
Near Surface ◽  
Oak Tree ◽  
Ground Penetrating ◽  
Constant Distribution

Ground-penetrating radar (GPR) is a geophysical technique widely used in near-surface non-invasive detecting. It has the ability to obtaining a high-resolution internal structure of living trunks. Full wave inversion (FWI) has been widely used to reconstruct the dielectric constant and conductivity distribution for cross-well application. However, in some cases, the amplitude information is not reliable due to the antenna coupling, radiation pattern and other effects. We present a multiscale phase inversion (MPI) method, which largely matches the phase information by normalizing the magnitude spectrum; in addition, a natural multiscale approach by integrating the input data with different times is implemented to partly mitigate the local minimal problem. Two synthetic GPR datasets generated from a healthy oak tree trunk and from a decayed trunk are tested by MPI and FWI. Field GPR dataset consisting of 30 common shot GPR data are acquired on a standing white oak tree (Quercus alba); the MPI and FWI methods are used to reconstruct the dielectric constant distribution of the tree cross-section. Results indicate that MPI has more tolerance to the starting model, noise level and source wavelet. It can provide a more accurate image of the dielectric constant distribution compared to the conventional FWI.

Looking for the hidden morphological signature of active faults in a Low Strain Rate region: clues from the eastern Kachchh region (NW India) 

2021 ◽  
Author(s):  
Eshaan Srivastava ◽  
Nicolò Parrino ◽  
Javed Malik ◽  
Fabrizio Pepe ◽  
Pierfrancesco Burrato
Keyword(s):  
Strain Rate ◽  
Multidisciplinary Approach ◽  
Surface Deformation ◽  
Active Faults ◽  
Tectonic Geomorphology ◽  
Seismic Events ◽  
Rate Region ◽  
Ongoing Work ◽  
Morphotectonic Evolution ◽  
Low Strain Rate

<p>The Kachchh region (NW India), a pericratonic rift basin delimited by E-W trending major thrust faults, is a Low Strain Rate region[PB1] . In this area, the tectonic forcing magnitude is stronger enough to trigger infrequent significant earthquakes but not enough to overprint the climatic forcing signature. As a consequence, the active faults sources of the largest seismic events are largely poorly known and their geomorphic signature is subdued. </p><p>Instrumental and paleoseismological evidence highlights that the eastern part of Kachchh experienced a significant number of seismic events such as the 1819-06-16 Allah Bund earthquake (Mw 7.8, also known as the Rann of Kutch earthquake), the 1956-07-21 Anjar earthquake (Mw 6.1), the 2001-01-26 Bhuj earthquake (Mw 7.6) and the 2006 events (Mw 5.0 and 5.6 earthquake occurred along Island Belt Fault and Gedi fault). </p><p>In this region, the unavailability of useful outcrop information due to a significant climatic overprinting of the fault’s morphological signatures hampers the detection and parametrization of actively deforming faults.</p><p>For this reason, in this ongoing work, we propose a multidisciplinary approach, aimed at detecting active geological structures and their related [PB2] surface deformation, which mainly consists of quantitative tectonic geomorphology and paleoseismological analyses and structural interpretation and modelling. Preliminary results are a morphotectonic evolution model and 3D fault model of the study area. Finally, we stress the concept that only a multidisciplinary approach could provide useful information to understand better the highly debated active tectonic framework of the study area.</p>

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.

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