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Earthquake Ground Motion Observation and Modelling

A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Remote Sensing in Geology, Geomorphology and Hydrology".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 32674

Special Issue Editors

Institute of Earth Sciences, University of Evora, 7000-645 Évora, Portugal
Interests: seismic source; ground motion prediction
Special Issues, Collections and Topics in MDPI journals
Prof. Bento Caldeira
E-Mail Website
Guest Editor
Institute of Earth Sciences, University of Evora, 7000-645 Évora, Portugal
Interests: seismic source; seismic networks
Special Issues, Collections and Topics in MDPI journals
Institute of Earth Sciences, University of Evora, 7000-645 Évora, Portugal
Interests: earthquake source seismology and seismic risk; 3D structure velocity models; strong ground motion modelling; seismotectonics and geodynamic; instrumental seismology and seismic networks; applied geophysics; geodynamic and geophysical models
Special Issues, Collections and Topics in MDPI journals
National Laboratory of Energy and Geology (LNEG)
Interests: active fault characterization; site effects studies; 3D geological modeling
National Laboratory for Civil Engineering (LNEC)
Interests: seismic groud motion modeling; ground motion prediction; seismic hazard and seismic risck assessment

Special Issue Information

Dear Colleagues,

Earthquakes remain one of the greatest natural disasters for modern society. Therefore, realistic and robust ground motion modeling for future events is one of the most challenging problems in seismology and earthquake engineering. This topic includes the study of source effects (e.g., rupture directivity, complex source dynamics), fault characterization (slip-rate, fault length, fault throw, etc.), surface deformation studies (InSAR, PSInSAR, DInSAR), propagation ground motion phenomena (including atenuation, seismic energy channeling, scattering effects, seismic elastic and viscoelastic modeling, and inversion) due to complexity in Earth structure, and local site effects (site basin effects and 3D geological modeling, liquefaction, soil classifications, topographic effects, nonlinearity). We also solicit contributions on ground motion networks. The quantitative and reliable assessment of those phenomena requires monitoring from high-quality to low-cost dense seismic networks, as well as small to medium aperture seismic arrays and big data management and analysis.

Professor José Fernando Borges
Professor Bento Caldeira
Professor Mourad Bezzeghoud
Dr. João Carvalho
Dr. Alexandra Carvalho
Guest Editors

Manuscript Submission Information

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Keywords

  • Ground motion modeling
  • Seismic source and path effects
  • Near surface structure
  • Site effect
  • Ground motion prediction equations (GMPE)
  • Vs30
  • Soil classification
  • Seismic viscoelastic modeling and inversion
  • Seismic strong motion networks

Published Papers (12 papers)

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20 pages, 36388 KiB  
Article
Source Parameter Inversion and Century-Scale Stress Triggering Analysis of the 2021 Maduo MW7.4 Earthquake Using GNSS and InSAR Displacement Fields
Remote Sens. 2023, 15(20), 5027; https://doi.org/10.3390/rs15205027 - 19 Oct 2023
Viewed by 689
Abstract
To explore the degree of constraint by Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data on the Maduo earthquake within a layered earth model structure and to gain an insight into the seismogenic mechanism and the seismic risk in [...] Read more.
To explore the degree of constraint by Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data on the Maduo earthquake within a layered earth model structure and to gain an insight into the seismogenic mechanism and the seismic risk in the surrounding area, this study employs D-InSAR technology to acquire the InSAR co-seismic deformation field of the Maduo earthquake on 22 May 2021. Utilizing both GNSS and InSAR data, the inversions constrained by single and joint data are conducted and compared to determine the co-seismic slip model and fault plane stress distribution of the Maduo earthquake. Additionally, this paper calculates the Coulomb stress changes induced by 14 M ≥ 7 strong earthquakes, considering co-seismic effects, post-seismic viscoelastic relaxation, and inter-seismic tectonic stress loading, on 19 fault segments within the Bayan Har block research area (96°E~106°E, 29°N~36°N) since 1900. The findings are as follows: (1) The maximum line-of-sight (LOS) deformation was approximately 0.9 m. The joint inversion rupture was primarily located in the Dongcao Along Lake section (~98.6°E), aligning with previous research outcomes. (2) The cumulative Coulomb stress at the Maduo earthquake’s source location was −0.1333 MPa, while the inter-seismic stress loading amounted to 0.0745 MPa. The East Kunlun Fault, Maduo–Gande Fault, Ganzi–Yushu Fault, and Dari Fault C exhibited considerable stress loading, warranting attention due to heightened seismic risk. (3) Based on three different co-seismic slip models, the stress disturbance results caused by the Maduo earthquake to the surrounding area and fault did not differ significantly. After the earthquake, the seismogenic fault still has high seismic risk. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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15 pages, 5993 KiB  
Article
Air Temperature Variations in Multiple Layers of the Indonesia Earthquake Based on the Tidal Forces
Remote Sens. 2023, 15(19), 4852; https://doi.org/10.3390/rs15194852 - 07 Oct 2023
Viewed by 533
Abstract
The air temperature changes in the Palu MW7.5 earthquake in Indonesia on 28 September 2018 were analyzed, based on the additive tectonic stress caused by celestial tidal-generating forces (ATSCTF) and air temperature data from the National Center for Environmental Prediction (NCEP). This paper [...] Read more.
The air temperature changes in the Palu MW7.5 earthquake in Indonesia on 28 September 2018 were analyzed, based on the additive tectonic stress caused by celestial tidal-generating forces (ATSCTF) and air temperature data from the National Center for Environmental Prediction (NCEP). This paper explored the variation characteristics of three-dimensional stratified of air temperature caused by seismic activity and the coupling relationship between air temperature changes and the tidal force. The background information for air temperature calculation was obtained from the tidal force changes, and the air temperature increment method was used to study the temperature evolution process of different periods in the study area. The results found that the tidal force acting on the critical state earthquake faults may be an important external factor inducing earthquakes, and there was indeed a significant air temperature increase anomaly during the Palu MW7.5 earthquake. The paper also summarized the abnormal characteristics of air temperature caused by seismic activity: the air temperature closer to the land’s surface has greater anomaly amplitude and a wider anomaly area than that of the upper air. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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28 pages, 9985 KiB  
Article
Seismic Sequence Analysis of the Arraiolos Zone, South Portugal, and Its Seismotectonic Implications: A Detailed Analysis of the Period 15 January–30 June 2018
Remote Sens. 2023, 15(18), 4494; https://doi.org/10.3390/rs15184494 - 12 Sep 2023
Viewed by 1045
Abstract
The Arraiolos Zone has been affected by the persistent superficial seismicity (focal depth < 20 km) of a weak magnitude (M < 4) and some events of a higher magnitude (M > 4), and is mainly located around the Aldeia da Serra village. [...] Read more.
The Arraiolos Zone has been affected by the persistent superficial seismicity (focal depth < 20 km) of a weak magnitude (M < 4) and some events of a higher magnitude (M > 4), and is mainly located around the Aldeia da Serra village. On 15 January 2018, at 11:51 UTC, the largest instrumental earthquake recorded in that area occurred, with a magnitude (ML 4.9) located northeast of Arraiolos, near the Aldeia da Serra village. This event was followed by a sequence of aftershocks with a magnitude (ML) ≤ 3.5. This seismic sequence was monitored by the designated temporary seismic network of Arraiolos, comprising 12 broadband seismic stations (CMG 6TD, 30 s) from the ICT (Institute of Earth Sciences, Évora) and 21 short-period stations (CDJ 2.0 Hz) from the IDL (Instituto Dom Luiz), distributed around the epicenter, within a radius of approximately 25 km. To infer the structure and kinematics of faults at depth and to constrain the crustal stress field in which the earthquakes occur, we use the polarities of the first P-wave arrivals and the S/P amplitude ratios to better constrain the focal mechanisms of 54 events selected, and apply the HASH algorithm. Overall, the good-quality (defined by the HASH parameters) focal solutions are characterized by a mixture of reverse and strike-slip mechanisms in our study area (AZS). Our seismicity and focal mechanism results suggest that the horizontal stress is more dominant than the vertical one and oriented in the NW–SE direction, parallel with the strike of the main faults. This analysis leads us to affirm that the ASZ is an active right-lateral shear zone. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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18 pages, 30401 KiB  
Article
Coseismic Faulting Model and Post-Seismic Surface Motion of the 2023 Turkey–Syria Earthquake Doublet Revealed by InSAR and GPS Measurements
Remote Sens. 2023, 15(13), 3327; https://doi.org/10.3390/rs15133327 - 29 Jun 2023
Cited by 7 | Viewed by 2180
Abstract
On 6 February 2023 (UTC), an earthquake doublet, consisting of the Mw 7.8 Pazarcik earthquake and the Mw 7.5 Elbistan earthquake, struck south-central Turkey and northwestern Syria, which was the largest earthquake that occurred in Turkey since the 1939 Erzincan earthquake. The faulting [...] Read more.
On 6 February 2023 (UTC), an earthquake doublet, consisting of the Mw 7.8 Pazarcik earthquake and the Mw 7.5 Elbistan earthquake, struck south-central Turkey and northwestern Syria, which was the largest earthquake that occurred in Turkey since the 1939 Erzincan earthquake. The faulting model of this earthquake was estimated based on the coseismic InSAR and GPS displacements. In addition, the best-fitting coseismic faulting model indicates that both the Pazarcik earthquake and the Elbistan earthquake were controlled by predominated left-lateral strike-slip motion, with slip peaks of 9.7 m and 10.8 m, respectively. The Coulomb failure stress (CFS) change suggests that the Pazarcik earthquake has a positive effect in triggering the rupture of the seismogenic fault of the Elbistan earthquake. Furthermore, these two main shocks promoted the occurrence of the Mw 6.3 strong aftershock. Additionally, it is found that the 2023 Turkey-Syria earthquake doublet increased the rupture risk of the Puturge segment of the EAF fault and the northern segment of the Dead Sea Fault (DSF). It is crucial to note that the northern segment of the DSF has not experienced a large earthquake in several centuries, highlighting the need for heightened attention to the potential seismic hazard of this segment. Finally, a deformation zone adjacent to the DSF was identified, potentially attributed to the motion of a blind submarine fault. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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29 pages, 12199 KiB  
Article
Sentinel-1 Interferometry and UAV Aerial Survey for Mapping Coseismic Ruptures: Mts. Sibillini vs. Mt. Etna Volcano
Remote Sens. 2023, 15(10), 2514; https://doi.org/10.3390/rs15102514 - 10 May 2023
Cited by 1 | Viewed by 1857
Abstract
The survey and structural analysis of surface coseismic ruptures are essential tools for characterizing seismogenic structures. In this work, a procedure to survey coseismic ruptures using satellite interferometric synthetic aperture radar (InSAR) data, directing the survey using Unmanned Aerial Vehicles (UAV), is proposed [...] Read more.
The survey and structural analysis of surface coseismic ruptures are essential tools for characterizing seismogenic structures. In this work, a procedure to survey coseismic ruptures using satellite interferometric synthetic aperture radar (InSAR) data, directing the survey using Unmanned Aerial Vehicles (UAV), is proposed together with a field validation of the results. The Sentinel-1 A/B Interferometric Wide (IW) Swath TOPSAR mode offers the possibility of acquiring images with a short revisit time. This huge amount of open data is extremely useful for geohazards monitoring, such as for earthquakes. Interferograms show the deformation field associated with earthquakes. Phase discontinuities appearing on wrapped interferograms or loss-of-coherence areas could represent small ground displacements associated with the fault’s ruptures. Low-altitude flight platforms such as UAV permit the acquisition of high resolution images and generate 3D spatial geolocalized clouds of data with centimeter-level accuracy. The generated topography maps and orthomosaic images are the direct products of this technology, allowing the possibility of analyzing geological structures from many viewpoints. We present two case studies. The first one is relative to the 2016 central Italian earthquakes, astride which the InSAR outcomes highlighted quite accurately the field displacement of extensional faults in the Mt. Vettore–M. Bove area. Here, the geological effect of the earthquake is represented by more than 35 km of ground ruptures with a complex pattern composed by subparallel and overlapping synthetic and antithetic fault splays. The second case is relative to the Mt. Etna earthquake of 26 December 2018, following which several ground ruptures were detected. The analysis of the unwrapped phase and the application of edge detector filtering and other discontinuity enhancers allowed the identification of a complex pattern of ground ruptures. In the Pennisi and Fiandaca areas different generation of ruptures can be distinguished, while previously unknown ruptures pertaining to the Acireale and Ragalna faults can be identify and analyzed. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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20 pages, 12775 KiB  
Article
Source Model and Triggered Aseismic Faulting of the 2021 Mw 7.3 Maduo Earthquake Revealed by the UAV-Lidar/Photogrammetry, InSAR, and Field Investigation
Remote Sens. 2022, 14(22), 5859; https://doi.org/10.3390/rs14225859 - 18 Nov 2022
Cited by 3 | Viewed by 2050
Abstract
Multi-source datasets, including the UAV-Lidar/Photogrammetry, InSAR, and field investigation data, have been used for revealing the complex surface displacement pattern and focal mechanism of the 2021 Maduo Mw 7.3 earthquake. First, a co-seismic surface deformation field was extracted from the Synthetic Aperture Radar [...] Read more.
Multi-source datasets, including the UAV-Lidar/Photogrammetry, InSAR, and field investigation data, have been used for revealing the complex surface displacement pattern and focal mechanism of the 2021 Maduo Mw 7.3 earthquake. First, a co-seismic surface deformation field was extracted from the Synthetic Aperture Radar (SAR) images captured by ALOS-2 and Sentinel-1 satellites. Second, the SAR pixel offset tracking results were adopted to detect the initial location of the seismogenic fault. Then, the Lidar digital elevation model with high spatial resolution and field investigation were employed to refine and verify the location of the seismogenic fault. It was found that bifurcated strike-slip rupture should account for the 2021 Maduo earthquake. As indicated by the estimated faulting model based on the InSAR data, the maximal fault slip was ~6.2 m, occurring in the southeast of the main seismogenic fault, and five remarkable slip concentrations controlled the surface displacement of the 2021 Maduo earthquake. Furthermore, the co- and post-seismic InSAR deformation, dilatation, shear strain, Coulomb failure stress, and aftershock sequence suggest that the co-seismic rupture of the two main seismogenic faults have triggered the aseismic slip along the Changmahe fault. Lastly, according to the Coulomb failure stress change due to the historical earthquakes and the 2021 Maduo earthquake, the 1937 M 7.8 earthquake predominantly controlled the Coulomb failure stress change along the Kunlun fault, and the Xidatan-Alake Lake and Maqin segments had a higher risk of future earthquake than the other segments. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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17 pages, 4456 KiB  
Article
Haiti Earthquake (Mw 7.2): Magnetospheric–Ionospheric–Lithospheric Coupling during and after the Main Shock on 14 August 2021
Remote Sens. 2022, 14(21), 5340; https://doi.org/10.3390/rs14215340 - 25 Oct 2022
Cited by 3 | Viewed by 1410
Abstract
In the last few decades, the efforts of the scientific community to search earthquake signatures in the atmospheric, ionospheric and magnetospheric media have grown rapidly. The increasing amount of good quality data from both ground stations and satellites has allowed for the detections [...] Read more.
In the last few decades, the efforts of the scientific community to search earthquake signatures in the atmospheric, ionospheric and magnetospheric media have grown rapidly. The increasing amount of good quality data from both ground stations and satellites has allowed for the detections of anomalies with high statistical significance such as ionospheric plasma density perturbations and/or atmospheric temperature and pressure changes. However, the identification of a causal link between the observed anomalies and their possible seismic trigger has so far been prevented by difficulties in the identification of confounders (such as solar and atmospheric activity) and the lack of a global analytical lithospheric–atmospheric–magnetospheric model able to explain (and possibly forecast) any anomalous signal. In order to overcome these problems, we have performed a multi-instrument analysis of a low-latitude seismic event by using high-quality data from both ground bases and satellites and preserving their statistical significance. An earthquake (Mw = 7.2) occurred in the Caribbean region on 14 August 2021 under both solar quiet and fair weather conditions, thus proving an optimal case study to reconstruct the link between the lithosphere, atmosphere, ionosphere, and magnetosphere. The good match between the observations and novel magnetospheric–ionospheric–lithospheric coupling (M.I.L.C.) modeling of the event confirmed that the fault break generated an atmospheric gravity wave that was able to mechanically perturb the ionospheric plasma density, in turn triggering a variation in the magnetospheric field line resonance frequency. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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18 pages, 8054 KiB  
Article
Source Model and Simulated Strong Ground Motion of the 2021 Yangbi, China Shallow Earthquake Constrained by InSAR Observations
Remote Sens. 2021, 13(20), 4138; https://doi.org/10.3390/rs13204138 - 15 Oct 2021
Cited by 6 | Viewed by 1861
Abstract
On 21 May 2021, an Mw 6.1 earthquake, causing considerable seismic damage, occurred in Yangbi County, Yunnan Province of China. To better understand the surface deformation pattern, source characteristics, seismic effect on nearby faults, and strong ground motion, we processed the ascending and [...] Read more.
On 21 May 2021, an Mw 6.1 earthquake, causing considerable seismic damage, occurred in Yangbi County, Yunnan Province of China. To better understand the surface deformation pattern, source characteristics, seismic effect on nearby faults, and strong ground motion, we processed the ascending and descending SAR images using the interferometric synthetic aperture radar (InSAR) technique to capture the radar line-of-sight (LOS) directional and 2.5-dimensional deformation. The source model was inverted from the LOS deformation observations. We further analyzed the Coulomb failure stress (CFS) transfer and peak ground acceleration (PGA) simulation based on the preferred source model. The results suggest that the 2021 Yangbi earthquake was dextral faulting with the maximum slip of 0.9 m on an unknown blind shallow fault, and the total geodetic moment was 1.4 × 1018 Nm (Mw 6.06). Comprehensive analysis of the CFS transfer and geological tectonics suggests that the Dian–Xibei pull-apart basin is still suffering high seismic hazards. The PGA result demonstrates that the seismic intensity of this event reached up to VIII. The entire process from InSAR deformation to source modeling and strong ground motion simulation suggests that the InSAR technique will play an important role in the assessment of earthquake disasters in the case of the shortening of the SAR imaging interval. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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17 pages, 17132 KiB  
Article
Insights from the P Wave Travel Time Tomography in the Upper Mantle Beneath the Central Philippines
Remote Sens. 2021, 13(13), 2449; https://doi.org/10.3390/rs13132449 - 23 Jun 2021
Cited by 5 | Viewed by 2013
Abstract
In this paper, we present a high resolution 3-D tomographic model of the upper mantle obtained from a large number of teleseismic travel time data from the ISC in the central Philippines. There are 2921 teleseismic events and 32,224 useful relative travel time [...] Read more.
In this paper, we present a high resolution 3-D tomographic model of the upper mantle obtained from a large number of teleseismic travel time data from the ISC in the central Philippines. There are 2921 teleseismic events and 32,224 useful relative travel time residuals picked to compute the velocity structure in the upper mantle, which was recorded by 87 receivers and satisfied the requirements of teleseismic tomography. Crustal correction was conducted to these data before inversion. The fast-marching method (FMM) and a subspace method were adopted in the forward step and inversion step, respectively. The present tomographic model clearly images steeply subducting high velocity anomalies along the Manila trench in the South China Sea (SCS), which reveals a gradual changing of the subduction angle and a gradual shallowing of the subduction depth from the north to the south. It is speculated that the change in its subduction depth and angle indicates the cessation of the SCS spreading from the north to the south, which also implies that the northern part of the SCS opened earlier than the southern part. Subduction of the Philippine Sea (PS) plate is exhibited between 14° N and 9° N, with its subduction direction changing from westward to eastward near 13° N. In the range of 11° N–9° N, the subduction of the Sulu Sea (SS) lies on the west side of PS plate. It is notable that obvious high velocity anomalies are imaged in the mantle transition zone (MTZ) between 14° N and 9° N, which are identified as the proto-SCS (PSCS) slabs and paleo-Pacific (PP) plate. It extends the location of the paleo-suture of PSCS-PP eastward from Borneo to the Philippines, which should be considered in studying the mechanism of the SCS and the tectonic evolution in SE Asia. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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29 pages, 21778 KiB  
Article
Destructive M6.2 Petrinja Earthquake (Croatia) in 2020—Preliminary Multidisciplinary Research
Remote Sens. 2021, 13(6), 1095; https://doi.org/10.3390/rs13061095 - 13 Mar 2021
Cited by 49 | Viewed by 11389
Abstract
On 28 December 2020, seismic activity in the wider Petrinja area strongly intensified after a period of relative seismological quiescence that had lasted more than 100 years (since the well-known M5.8 Kupa Valley earthquake of 1909, which is known based on the discovery [...] Read more.
On 28 December 2020, seismic activity in the wider Petrinja area strongly intensified after a period of relative seismological quiescence that had lasted more than 100 years (since the well-known M5.8 Kupa Valley earthquake of 1909, which is known based on the discovery of the Mohorovičić discontinuity). The day after the M5 foreshock, a destructive M6.2 mainshock occurred. Outcomes of preliminary seismological, geological and SAR image analyses indicate that the foreshocks, mainshock and aftershocks were generated due to the (re)activation of a complex fault system—the intersection of longitudinal NW–SE right-lateral and transverse NE–SW left-lateral faults along the transitional contact zone of the Dinarides and the Pannonian Basin. According to a survey of damage to buildings, approximately 15% of buildings were very heavily damaged or collapsed. Buildings of special or outstanding historical or cultural heritage significance mostly collapsed or became unserviceable. A preliminary analysis of the earthquake ground motion showed that in the epicentral area, the estimated peak ground acceleration PGA values for the bedrock ranged from 0.29 to 0.44 g. In the close Petrinja epicentral area that is characterized by the superficial deposits, significant ground failures were reported within local site effects. Based on that finding and building damage, we assume that the resulting peak ground acceleration (PGAsite) values were likely between 0.4 and 0.6 g depending on the local site characteristics and the distance from the epicentre. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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25 pages, 21778 KiB  
Article
Imaging of the Upper Mantle Beneath Southeast Asia: Constrained by Teleseismic P-Wave Tomography
Remote Sens. 2020, 12(18), 2975; https://doi.org/10.3390/rs12182975 - 13 Sep 2020
Cited by 4 | Viewed by 3289
Abstract
It is of great significance to construct a three-dimensional underground velocity model for the study of geodynamics and tectonic evolution. Southeast Asia has attracted much attention due to its complex structural features. In this paper, we collected relative travel time residuals data for [...] Read more.
It is of great significance to construct a three-dimensional underground velocity model for the study of geodynamics and tectonic evolution. Southeast Asia has attracted much attention due to its complex structural features. In this paper, we collected relative travel time residuals data for 394 stations distributed in Southeast Asia from 2006 to 2019, and 14,011 seismic events were obtained. Then, teleseismic tomography was applied by using relative travel time residuals data to invert the velocity where the fast marching method (FMM) and subspace method were used for every iteration. A novel 3D P-wave velocity model beneath Southeast Asia down to 720 km was obtained using this approach. The tomographic results suggest that the southeastern Tibetan Plateau, the Philippines, Sumatra, and Java, and the deep part of Borneo exhibit high velocity anomalies, while low velocity anomalies were found in the deep part of the South China Sea (SCS) basin and in the shallow part of Borneo and areas near the subduction zone. High velocity anomalies can be correlated to subduction plates and stable land masses, while low velocity anomalies can be correlated to island arcs and upwelling of mantle material caused by subduction plates. We found a southward subducting high velocity body in the Nansha Trough, which was presumed to be a remnant of the subduction of the Dangerous Grounds into Borneo. It is further inferred that the Nansha Trough and the Dangerous Grounds belong to the same tectonic unit. According to the tomographic images, a high velocity body is located in the deep underground of Indochina–Natuna Island–Borneo–Palawan, depth range from 240 km to 660 km. The location of the high velocity body is consistent with the distribution range of the ophiolite belt, so we speculate that the high velocity body is the remnant of thee Proto-South China Sea (PSCS) and Paleo-Tethys. This paper conjectures that the PSCS was the southern branch of Paleo-Tethys and the gateway between Paleo-Tethys and the Paleo-Pacific Ocean. Due to the squeeze of the Australian plate, PSCS closed from west to east in a scissor style, and was eventually extinct under Borneo. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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15 pages, 5965 KiB  
Technical Note
Co-Seismic Inversion and Post-Seismic Deformation Mechanism Analysis of 2019 California Earthquake
Remote Sens. 2021, 13(4), 608; https://doi.org/10.3390/rs13040608 - 08 Feb 2021
Cited by 3 | Viewed by 2226
Abstract
In July 2019, a series of seismic events, including a magnitude (Mw) 7.1 mainshock and Mw 6.4 foreshock, occurred in Eastern California. Studying these seismic events can significantly improve our understanding of the Eastern California tectonic environment. Sentinel-1A and ALOS-2 PALSAR images were [...] Read more.
In July 2019, a series of seismic events, including a magnitude (Mw) 7.1 mainshock and Mw 6.4 foreshock, occurred in Eastern California. Studying these seismic events can significantly improve our understanding of the Eastern California tectonic environment. Sentinel-1A and ALOS-2 PALSAR images were utilized to obtain co-seismic deformation fields, including mainshock and foreshock deformation. The Okada elastic dislocation model and ascending and descending orbit results were used to invert the co-seismic slip distribution and obtain a co-seismic focal mechanism solution. Using ascending Sentinel-1A images, a time-series deformation was obtained for 402 d after the earthquake, and the deformation evolution mechanism was analyzed. The maximum uplift caused by the co-seismic mechanism reached 1.5 m in the line of sight (LOS), and the maximum subsidence reached 1 m in the LOS. For 402 d after the earthquake, the area remained active, and its deformation was dominated by after-slip. The co-seismic inversion results illustrated that California earthquakes were mainly strike-slip. The co-seismic inversion magnitude was approximately Mw 7.08. The Coulomb stress change illustrated that the seismic moment caused by the co-seismic slip was 4.24 × 1026 N × m, which is approximately Mw 7.06. This finding is consistent with the co-seismic slip distribution inversion results. Full article
(This article belongs to the Special Issue Earthquake Ground Motion Observation and Modelling)
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