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3 pages, 185 KiB

Open AccessEditorial

Editorial for the Special Issue: “Ground Deformation Patterns Detection by InSAR and GNSS Techniques”

by Mimmo Palano

Remote Sens. 2022, 14(5), 1104; https://doi.org/10.3390/rs14051104 - 24 Feb 2022

Cited by 2 | Viewed by 2604

Abstract

In the last two decades, the rapid growth in continuous Global Navigation Satellite Systems (GNSS) networks and improvements in Interferometric Synthetic Aperture Radar (InSAR) imaging allowed the acquisition of continuous and spatially extensive datasets over large regions of Earth, significantly increasing the range [...] Read more.

In the last two decades, the rapid growth in continuous Global Navigation Satellite Systems (GNSS) networks and improvements in Interferometric Synthetic Aperture Radar (InSAR) imaging allowed the acquisition of continuous and spatially extensive datasets over large regions of Earth, significantly increasing the range of geoscience applications [...] Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

Research

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12 pages, 3585 KiB

Open AccessArticle

Shrinking of Ischia Island (Italy) from Long-Term Geodetic Data: Implications for the Deflation Mechanisms of Resurgent Calderas and Their Relationships with Seismicity

by Alessandro Galvani, Giuseppe Pezzo, Vincenzo Sepe and Guido Ventura

Remote Sens. 2021, 13(22), 4648; https://doi.org/10.3390/rs13224648 - 18 Nov 2021

Cited by 9 | Viewed by 2584

Abstract

The identification of the mechanisms responsible for the deformation of calderas is of primary importance for our understanding of the dynamics of magmatic systems and the evaluation of volcanic hazards. We analyze twenty years (1997–2018) of geodetic measurements on Ischia Island (Italy), which [...] Read more.

The identification of the mechanisms responsible for the deformation of calderas is of primary importance for our understanding of the dynamics of magmatic systems and the evaluation of volcanic hazards. We analyze twenty years (1997–2018) of geodetic measurements on Ischia Island (Italy), which include the Mt. Epomeo resurgent block, and is affected by hydrothermal manifestations and shallow seismicity. The data from the GPS Network and the leveling route show a constant subsidence with values up to −15 ± 2.0 mm/yr and a centripetal displacement rate with the largest deformations on the southern flank of Mt. Epomeo. The joint inversion of GPS and levelling data is consistent with a 4 km deep source deflating by degassing and magma cooling below the southern flank of Mt. Epomeo. The depth of the source is supported by independent geophysical data. The Ischia deformation field is not related to the instability of the resurgent block or extensive gravity or tectonic processes. The seismicity reflects the dynamics of the shallow hydrothermal system being neither temporally nor spatially related to the deflation. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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15 pages, 7798 KiB

Open AccessArticle

Geodetic Model of the March 2021 Thessaly Seismic Sequence Inferred from Seismological and InSAR Data

by Vincenzo De Novellis, Diego Reale, Guido Maria Adinolfi, Eugenio Sansosti and Vincenzo Convertito

Remote Sens. 2021, 13(17), 3410; https://doi.org/10.3390/rs13173410 - 27 Aug 2021

Cited by 20 | Viewed by 3027

Abstract

In this work, we propose a geodetic model for the March 2021 Thessaly seismic sequence (TSS). We used the interferometric synthetic aperture radar (InSAR) technique and exploited a dataset of Sentinel-1 images to successfully detect the surface deformation caused by three major events [...] Read more.

In this work, we propose a geodetic model for the March 2021 Thessaly seismic sequence (TSS). We used the interferometric synthetic aperture radar (InSAR) technique and exploited a dataset of Sentinel-1 images to successfully detect the surface deformation caused by three major events of the sequence and constrain their kinematics, further strengthened by seismic data analysis. Our geodetic inversions are consistent with the activation of distinct blind faults previously unknown in this region: three belonging to the NE-dipping normal fault associated with the Mw 6.3 and Mw 6.0 events, and one belonging to the SW-dipping normal fault associated with the Mw 5.6, the last TSS major event. We performed a Coulomb stress transfer analysis and a 1D pore pressure diffusivity modeling to investigate the space–time evolution of the sequence; our results indicate that the seismic sequence developed in a sort of domino effect. The combination of the lack of historical records of large earthquakes in this area and the absence of mapped surface features produced by past faulting make seismic hazard estimation difficult for this area: InSAR data analysis and modeling have proven to be an extremely useful tool in helping to constrain the rupture characteristics. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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14 pages, 4735 KiB

Open AccessFeature PaperArticle

The 2008–2010 Subsidence of Dallol Volcano on the Spreading Erta Ale Ridge: InSAR Observations and Source Models

by Maurizio Battaglia, Carolina Pagli and Stefano Meuti

Remote Sens. 2021, 13(10), 1991; https://doi.org/10.3390/rs13101991 - 19 May 2021

Cited by 10 | Viewed by 3081

Abstract

In this work, we study the subsidence of Dallol, an explosive crater and hydrothermal area along the spreading Erta Ale ridge of Afar (Ethiopia). No volcanic products exist at the surface. However, a diking episode in 2004, accompanied by dike-induced faulting, indicates that [...] Read more.

In this work, we study the subsidence of Dallol, an explosive crater and hydrothermal area along the spreading Erta Ale ridge of Afar (Ethiopia). No volcanic products exist at the surface. However, a diking episode in 2004, accompanied by dike-induced faulting, indicates that Dallol is an active volcanic area. The 2004 diking episode was followed by quiescence until subsidence started in 2008. We use InSAR to measure the deformation, and inverse, thermoelastic and poroelastic modelling to understand the possible causes of the subsidence. Analysis of InSAR data from 2004–2010 shows that subsidence, centered at Dallol, initiated in October 2008, and continued at least until February 2010 at an approximately regular rate of up to 10 cm/year. The inversion of InSAR average velocities finds that the source causing the subsidence is shallow (depth between 0.5 and 1.5 km), located under Dallol and with a volume decrease between −0.63 and −0.26 × 10⁶ km³/year. The most likely explanation for the subsidence of Dallol volcano is a combination of outgassing (depressurization), cooling and contraction of the roof of a shallow crustal magma chamber or of the hydrothermal system. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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24 pages, 10172 KiB

Open AccessArticle

Ground Deformation Modelling of the 2020 Mw6.9 Samos Earthquake (Greece) Based on InSAR and GNSS Data

by Vassilis Sakkas

Remote Sens. 2021, 13(9), 1665; https://doi.org/10.3390/rs13091665 - 24 Apr 2021

Cited by 24 | Viewed by 4349

Abstract

Modelling of combined Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data was performed to characterize the source of the Mw6.9 earthquake that occurred to the north of Samos Island (Aegean Sea) on 30 October 2020. Pre-seismic analysis revealed an [...] Read more.

Modelling of combined Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) data was performed to characterize the source of the Mw6.9 earthquake that occurred to the north of Samos Island (Aegean Sea) on 30 October 2020. Pre-seismic analysis revealed an NNE–SSW extensional regime with normal faults along an E–W direction. Co-seismic analysis showed opening of the epicentral region with horizontal and vertical displacements of ~350 mm and ~90 mm, respectively. Line-of-sight (LOS) interferometric vectors were geodetically corrected using the GNSS data and decomposed into E–W and vertical displacement components. Compiled interferometric maps reveal that relatively large ground displacements had occurred in the western part of Samos but had attenuated towards the eastern and southern parts. Alternating motions occurred along and across the main geotectonic units of the island. The best-fit fault model has a two-segment listric fault plane (average slip 1.76 m) of normal type that lies adjacent to the northern coastline of Samos. This fault plane is 35 km long, extends to 15 km depth, and dips to the north at 60° and 40° angles for the upper and lower parts, respectively. A predominant dip-slip component and a substantial lateral one were modelled. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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18 pages, 9620 KiB

Open AccessArticle

Multi-Segment Rupture Model of the 2016 Kumamoto Earthquake Revealed by InSAR and GPS Data

by Zhongqiu He, Ting Chen, Mingce Wang and Yanchong Li

Remote Sens. 2020, 12(22), 3721; https://doi.org/10.3390/rs12223721 - 12 Nov 2020

Cited by 11 | Viewed by 3325

Abstract

The 2016 Kumamoto earthquake, including two large (Mw ≥ 6.0) foreshocks and an Mw 7.0 mainshock, occurred in the Hinagu and Futagawa fault zones in the middle of Kyushu island, Japan. Here, we obtain the complex coseismic deformation field associated with this earthquake [...] Read more.

The 2016 Kumamoto earthquake, including two large (Mw ≥ 6.0) foreshocks and an Mw 7.0 mainshock, occurred in the Hinagu and Futagawa fault zones in the middle of Kyushu island, Japan. Here, we obtain the complex coseismic deformation field associated with this earthquake from Advanced Land Observation Satellite-2 (ALOS-2) and Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) data. These InSAR data, in combination with available Global Positioning System (GPS) data, are then used to determine an optimal four-segment fault geometry with the jRi method, which considers both data misfit and the perturbation error from data noise. Our preferred slip distribution model indicates that the rupture is dominated by right-lateral strike-slip, with a significant normal slip component. The largest asperity is located on the northern segment of the Futagawa fault, with a maximum slip of 5.6 m at a 5–6 km depth. The estimated shallow slips along the Futagawa fault and northern Hinagu fault are consistent with the displacements of surface ruptures from the field investigation, suggesting a shallow slip deficit. The total geodetic moment release is estimated to be 4.89 × 10¹⁹ Nm (Mw 7.09), which is slightly larger than seismological estimates. The calculated static Coulomb stress changes induced by the preferred slip distribution model cannot completely explain the spatial distribution of aftershocks. Sensitivity analysis of Coulomb stress change implies that aftershocks in the stress shadow area may be driven by aseismic creep or triggered by dynamic stress transfer, requiring further investigation. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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19 pages, 3131 KiB

Open AccessArticle

Towards a PS-InSAR Based Prediction Model for Building Collapse: Spatiotemporal Patterns of Vertical Surface Motion in Collapsed Building Areas—Case Study of Alexandria, Egypt

by Bahaa Mohamadi, Timo Balz and Ali Younes

Remote Sens. 2020, 12(20), 3307; https://doi.org/10.3390/rs12203307 - 12 Oct 2020

Cited by 13 | Viewed by 4672

Abstract

Buildings are vulnerable to collapse incidents. We adopt a workflow to detect unusual vertical surface motions before building collapses based on PS-InSAR time series analysis and spatiotemporal data mining techniques. Sentinel-1 ascending and descending data are integrated to decompose vertical deformation in the [...] Read more.

Buildings are vulnerable to collapse incidents. We adopt a workflow to detect unusual vertical surface motions before building collapses based on PS-InSAR time series analysis and spatiotemporal data mining techniques. Sentinel-1 ascending and descending data are integrated to decompose vertical deformation in the city of Alexandria, Egypt. Collapsed building data were collected from official sources, and overlayed on PS-InSAR vertical deformation results. Time series deformation residuals are used to create a space–time cube in the ArcGIS software environment and analyzed by emerging hot spot analysis to extract spatiotemporal patterns for vertical deformation around collapsed buildings. Our results show two spatiotemporal patterns of new cold spot or new hot spot before the incidents in 66 out of 68 collapsed buildings between May 2015 and December 2018. The method was validated in detail on four collapsed buildings between January and May 2019, proving the applicability of this workflow to create a temporal vulnerability map for building collapse monitoring. This study is a step forward to create a PS-InSAR based model for building collapse prediction in the city. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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26 pages, 3695 KiB

Open AccessArticle

New Insights into Long-Term Aseismic Deformation and Regional Strain Rates from GNSS Data Inversion: The Case of the Pollino and Castrovillari Faults

by Gabriele Cambiotti, Mimmo Palano, Barbara Orecchio, Anna Maria Marotta, Riccardo Barzaghi, Giancarlo Neri and Roberto Sabadini

Remote Sens. 2020, 12(18), 2921; https://doi.org/10.3390/rs12182921 - 9 Sep 2020

Cited by 5 | Viewed by 2709

Abstract

We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides [...] Read more.

We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides a refined estimate of the upper bound of the strain accumulation process. As case study, we apply this method to a six year GNSS campaign (2003–2008) set up in the southern portion of the Pollino Range over the Castrovillari and Pollino faults. We show that regional deformation alone cannot explain the observed deformation pattern and implies high geodetic strain rate, with a WSW-ENE extension of

86 \pm 41 \times 10^{- 9} / yr

. Allowing for the possibility of fault creep, the modelling of GNSS velocities is consistent with their uncertainties and they are mainly explained by a shallow creep over the Pollino fault, with a normal/strike-slip mechanism up to 5 mm/yr. The regional strain rate decrease by about 70 percent and is characterized by WNW-ESE extension of

24 \pm 28 \times 10^{- 9} / yr

. The large uncertainties affecting our estimate of regional strain rate do not allow infering whether the tectonic regime of the area is extensional or strike-slip, although the latter is slightly more likely. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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11 pages, 4663 KiB

Open AccessArticle

Source Model for Sabancaya Volcano Constrained by DInSAR and GNSS Surface Deformation Observation

by Gregorio Boixart, Luis F. Cruz, Rafael Miranda Cruz, Pablo A. Euillades, Leonardo D. Euillades and Maurizio Battaglia

Remote Sens. 2020, 12(11), 1852; https://doi.org/10.3390/rs12111852 - 8 Jun 2020

Cited by 15 | Viewed by 5421

Abstract

Sabancaya is the most active volcano of the Ampato-Sabancaya Volcanic Complex (ASVC) in southern Perú and has been erupting since 2016. The analysis of ascending and descending Sentinel-1 orbits (DInSAR) and Global Navigation Satellite System (GNSS) datasets from 2014 to 2019 imaged a [...] Read more.

Sabancaya is the most active volcano of the Ampato-Sabancaya Volcanic Complex (ASVC) in southern Perú and has been erupting since 2016. The analysis of ascending and descending Sentinel-1 orbits (DInSAR) and Global Navigation Satellite System (GNSS) datasets from 2014 to 2019 imaged a radially symmetric inflating area, uplifting at a rate of 35 to 50 mm/yr and centered 5 km north of Sabancaya. The DInSAR and GNSS data were modeled independently. We inverted the DInSAR data to infer the location, depth, and volume change of the deformation source. Then, we verified the DInSAR deformation model against the results from the inversion of the GNSS data. Our modelling results suggest that the imaged inflation pattern can be explained by a source 12 to 15 km deep, with a volume change rate between 26 × 10⁶ m³/yr and 46 × 10⁶ m³/yr, located between the Sabancaya and Hualca Hualca volcano. The observed regional inflation pattern, concentration of earthquake epicenters north of the ASVC, and inferred location of the deformation source indicate that the current eruptive activity at Sabancaya is fed by a deep regional reservoir through a lateral magmatic plumbing system. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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22 pages, 7182 KiB

Open AccessArticle

Detection of Terrain Deformations Using InSAR Techniques in Relation to Results on Terrain Subsidence (Ciudad de Zaruma, Ecuador)

by Marcelo Cando Jácome, A. M. Martinez-Graña and V. Valdés

Remote Sens. 2020, 12(10), 1598; https://doi.org/10.3390/rs12101598 - 17 May 2020

Cited by 19 | Viewed by 5865

Abstract

In Zaruma city, located in the El Oro province, Ecuador, gold mines have been exploited since before the colonial period. According to the chroniclers of that time, 2700 tons of gold were sent to Spain. This exploitation continued in the colonial, republican, and [...] Read more.

In Zaruma city, located in the El Oro province, Ecuador, gold mines have been exploited since before the colonial period. According to the chroniclers of that time, 2700 tons of gold were sent to Spain. This exploitation continued in the colonial, republican, and current periods. The legalized mining operation, with foreign companies such as South Development Company (SADCO) and national companies such as the Associated Industrial Mining Company (CIMA), exploited the mines legally until they dissolved and gave rise to small associations, artisanal mining, and, with them, illegal mining. Illegal underground mining is generated without order and technical direction, and cuts mineralized veins in andesitic rocks, volcanic breccia, tuffs and dacitic porphyry that have been intensely weatherized from surface to more than 80 meters depth. These rocks have become totally altered soils and saprolites, which have caused the destabilization of the mining galleries and the superficial collapse of the topographic relief. The illegal miners, called "Sableros", after a period of exploitation at one site, when the gold grade decreased, abandon these illegal mines to begin other mining work at other sites near mineralized veins or near legalized mining galleries in operation. Due to this anthropic activity of illegal exploitation through the mining galleries and “piques” that remain under the colonial center of the city, sinkings have occurred in various sectors detected and reported in various technical reports since 1995. The Ecuadorian Government has been unable to control these illegal mining activities. The indicators of initial subsidence of the terrain are small movements that accumulate over a time and that can be detected with InSAR technology in large areas, improving the traditional detection performed with geodetic instrumentation such as total stations and geodetic marks. Recent subsidence at Fe y Alegría-La Immaculada School, the city’s hospital and Gonzalo Pizarro Street, indicates that there is active subsidence in these and other sectors of the city. The dynamic triggers that have possibly accelerated the rate of subsidence and landslides on the slopes are earthquakes (5 to 6 Mw) and heavy rains in deforested areas. Although several sinks and active subsidence caused by underground mining were detected in these sectors and in other sectors in previous decades, which were detailed in various reports of geological hazards prepared by specialized institutions, underground mining has continued under the colonial city center. In view of the existing risk, this article presents a forecasting methodology for the constant monitoring of long-term soil subsidence, especially in the center of the colonial city, which is a national cultural heritage and candidate for the cultural heritage of humanity. This is a proposal for the use of synthetic aperture radar interferometry (InSAR) for the subsidence analysis of topographic relief in the colonial area of the city of Zaruma by illegal mining galleries. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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14 pages, 22292 KiB

Open AccessArticle

Seismogenic Source Model of the 2019, M_w 5.9, East-Azerbaijan Earthquake (NW Iran) through the Inversion of Sentinel-1 DInSAR Measurements

by Emanuela Valerio, Mariarosaria Manzo, Francesco Casu, Vincenzo Convertito, Claudio De Luca, Michele Manunta, Fernando Monterroso, Riccardo Lanari and Vincenzo De Novellis

Remote Sens. 2020, 12(8), 1346; https://doi.org/10.3390/rs12081346 - 24 Apr 2020

Cited by 12 | Viewed by 5188

Abstract

In this work, we investigate the M_w 5.9 earthquake occurred on 7 November 2019 in the East-Azerbaijan region, in northwestern Iran, which is inserted in the tectonic framework of the East-Azerbaijan Plateau, a complex mountain belt that contains internal major fold-and-thrust belts. [...] Read more.

In this work, we investigate the M_w 5.9 earthquake occurred on 7 November 2019 in the East-Azerbaijan region, in northwestern Iran, which is inserted in the tectonic framework of the East-Azerbaijan Plateau, a complex mountain belt that contains internal major fold-and-thrust belts. We first analyze the Differential Synthetic Aperture Radar Interferometry (DInSAR) measurements obtained by processing the data collected by the Sentinel-1 constellation along ascending and descending orbits; then, we invert the achieved results through analytical modelling, in order to better constrain the geometry and characteristics of the seismogenic source. The retrieved fault model shows a rather shallow seismic structure, with a center depth at about 3 km, approximately NE–SW-striking and southeast-dipping, characterized by a left-lateral strike-slip fault mechanism (strike = 29.17°, dip = 79.29°, rake = −4.94°) and by a maximum slip of 0.80 m. By comparing the inferred fault with the already published geological structures, the retrieved solution reveals a minor fault not reported in the geological maps available in the open literature, whose kinematics is compatible with that of the surrounding structures, with the local and regional stress states and with the performed field observations. Moreover, by taking into account the surrounding geological structures reported in literature, we also use the retrieved fault model to calculate the Coulomb Failure Function at the nearby receiver faults. We show that this event may have encouraged, with a positive loading, the activation of the considered receiver faults. This is also confirmed by the distribution of the aftershocks that occurred near the considered surrounding structures. The analysis of the seismic events nucleated along the left-lateral strike-slip minor faults of the East-Azerbaijan Plateau, such as the one analyzed in this work, is essential to improve our knowledge on the seismic hazard estimation in northwestern Iran. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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17 pages, 5160 KiB

Open AccessArticle

3D Displacement Field of Wenchuan Earthquake Based on Iterative Least Squares for Virtual Observation and GPS/InSAR Observations

by Luyun Xiong, Caijun Xu, Yang Liu, Yangmao Wen and Jin Fang

Remote Sens. 2020, 12(6), 977; https://doi.org/10.3390/rs12060977 - 18 Mar 2020

Cited by 11 | Viewed by 4008

Abstract

The acquisition of a 3D displacement field can help to understand the crustal deformation pattern of seismogenic faults and deepen the understanding of the earthquake nucleation. The data for 3D displacement field extraction are usually from GPS/interferometric synthetic aperture radar (InSAR) observations, and [...] Read more.

The acquisition of a 3D displacement field can help to understand the crustal deformation pattern of seismogenic faults and deepen the understanding of the earthquake nucleation. The data for 3D displacement field extraction are usually from GPS/interferometric synthetic aperture radar (InSAR) observations, and the direct solution method is usually adopted. We proposed an iterative least squares for virtual observation (VOILS) based on the maximum a posteriori estimation criterion of Bayesian theorem to correct the errors caused by the GPS displacement interpolation process. Firstly, in the simulation examples, both uniform and non-uniform sampling schemes for GPS observation were used to extract 3D displacement. On the basis of the experimental results of the reverse fault, the normal fault with a strike-slip component, and the strike-slip fault with a reverse component, we found that the VOILS method is better than the direct solution method in both horizontal and vertical directions. When a uniform sampling scheme was adopted, the percentages of improvement for the reverse fault ranged from 3% to 9% and up to 70%, for the normal fault with a strike-slip component ranging from 4% to 8% and up to 68%, and for the strike-slip fault with a reverse component ranging from 1% to 8% and up to 22%. After this, the VOILS method was applied to extract the 3D displacement field of the 2008 Mw 7.9 Wenchuan earthquake. In the East–West (E) direction, the maximum displacement of the hanging wall was 1.69 m and 2.15 m in the footwall. As for the North–South (N) direction, the maximum displacement of the hanging wall was 0.82 m for the southwestern, 0.95 m for the northeastern, while that of the footwall was 0.77 m. In the vertical (U) direction, the maximum uplift was 1.19 m and 0.95 m for the subsidence, which was significantly different from the direct solution method. Finally, the derived vertical displacements were also compared with the ruptures from field investigations, indicating that the VOILS method can reduce the impact of the interpolated errors on parameter estimations to some extent. The simulation experiments and the case study of the 3D displacement field for the 2008 Wenchuan earthquake suggest that the VOILS method proposed in this study is feasible and effective, and the degree of improvement in the vertical direction is particularly significant. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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27 pages, 10978 KiB

Open AccessArticle

Geodetic Deformation versus Seismic Crustal Moment-Rates: Insights from the Ibero-Maghrebian Region

by Federica Sparacino, Mimmo Palano, José Antonio Peláez and José Fernández

Remote Sens. 2020, 12(6), 952; https://doi.org/10.3390/rs12060952 - 16 Mar 2020

Cited by 29 | Viewed by 5439

Abstract

Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazards. We performed such a comparison for the Southeastern Iberia—Maghreb region. Located at the western Mediterranean border along the Eurasia–Nubia plate convergence, the region has been subject to a number of [...] Read more.

Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazards. We performed such a comparison for the Southeastern Iberia—Maghreb region. Located at the western Mediterranean border along the Eurasia–Nubia plate convergence, the region has been subject to a number of large earthquakes (M ≥ 6.5) in the last millennium. To this end, on the basis of available geological, tectonic, and seismological data, we divided the study area into twenty-five seismogenic source zones. Many of these seismogenic source zones, comprising the Western Betics, the Western Rif mountains, and the High, Middle, and Saharan Atlas, are characterized by seismic/geodetic ratio values lower than 23%, evidencing their prevailing aseismic behavior. Intermediate seismic/geodetic ratio values (between 35% and 60%) have been observed for some zones belonging to the Eastern Betics, the central Rif, and the Middle Atlas, indicating how crustal seismicity accounts only for a moderate fraction of the total deformation-rate budget. High seismic/geodetic ratio values (> 95%) have been observed along the Tell Atlas, highlighting a fully seismic deformation. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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20 pages, 15143 KiB

Open AccessArticle

A Covariance-Based Approach to Merging InSAR and GNSS Displacement Rate Measurements

by Alessandro Parizzi, Fernando Rodriguez Gonzalez and Ramon Brcic

Remote Sens. 2020, 12(2), 300; https://doi.org/10.3390/rs12020300 - 16 Jan 2020

Cited by 19 | Viewed by 5337

Abstract

This paper deals with the integration of deformation rates derived from Synthetic Aperture Radar Interferometry (InSAR) and Global Navigation Satellite System (GNSS) data. The proposed approach relies on knowledge of the variance/covariance of both InSAR and GNSS measurements so that they may be [...] Read more.

This paper deals with the integration of deformation rates derived from Synthetic Aperture Radar Interferometry (InSAR) and Global Navigation Satellite System (GNSS) data. The proposed approach relies on knowledge of the variance/covariance of both InSAR and GNSS measurements so that they may be combined accounting for the spectral properties of their errors, hence preserving all spatial frequencies of the deformation detected by the two techniques. The variance/covariance description of the output product is also provided. A performance analysis is carried out on realistic simulated scenarios in order to show the boundaries of the technique. The proposed approach is finally applied to real data. Five Sentinel-1A/B stacks acquired over two different areas of interest are processed and discussed. The first example is a merged deformation map of the northern part of the Netherlands for both ascending and descending geometries. The second example shows the deformation at the junction between the North and East Anatolian Fault using three consecutive descending stacks. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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Review

Jump to: Editorial, Research, Other

27 pages, 4206 KiB

Open AccessReview

Review of Works Combining GNSS and InSAR in Europe

by Matteo Del Soldato, Pierluigi Confuorto, Silvia Bianchini, Paolo Sbarra and Nicola Casagli

Remote Sens. 2021, 13(9), 1684; https://doi.org/10.3390/rs13091684 - 27 Apr 2021

Cited by 45 | Viewed by 8375

Abstract

The Global Navigation Satellite System (GNSS) and Synthetic Aperture Radar Interferometry (InSAR) can be combined to achieve different goals, owing to their main principles. Both enable the collection of information about ground deformation due to the differences of two consequent acquisitions. Their variable [...] Read more.

The Global Navigation Satellite System (GNSS) and Synthetic Aperture Radar Interferometry (InSAR) can be combined to achieve different goals, owing to their main principles. Both enable the collection of information about ground deformation due to the differences of two consequent acquisitions. Their variable applications, even if strictly related to ground deformation and water vapor determination, have encouraged the scientific community to combine GNSS and InSAR data and their derivable products. In this work, more than 190 scientific contributions were collected spanning the whole European continent. The spatial and temporal distribution of such studies, as well as the distinction in different fields of application, were analyzed. Research in Italy, as the most represented nation, with 47 scientific contributions, has been dedicated to the spatial and temporal distribution of its studied phenomena. The state-of-the-art of the various applications of these two combined techniques can improve the knowledge of the scientific community and help in the further development of new approaches or additional applications in different fields. The demonstrated usefulness and versability of the combination of GNSS and InSAR remote sensing techniques for different purposes, as well as the availability of free data, EUREF and GMS (Ground Motion Service), and the possibility of overcoming some limitations of these techniques through their combination suggest an increasingly widespread approach. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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Other

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10 pages, 7356 KiB

Open AccessLetter

The November 2019 Seismic Sequence in Albania: Geodetic Constraints and Fault Interaction

by Alessandro Caporali, Mario Floris, Xue Chen, Bilbil Nurce, Mauro Bertocco and Joaquin Zurutuza

Remote Sens. 2020, 12(5), 846; https://doi.org/10.3390/rs12050846 - 5 Mar 2020

Cited by 17 | Viewed by 4391

Abstract

The seismic sequence of November 2019 in Albania culminating with the Mw = 6.4 event of 26 November 2019 was examined from the geodetic (InSAR and GNSS), structural, and historical viewpoints, with some ideas on possible areas of greater hazard. We present accurate [...] Read more.

The seismic sequence of November 2019 in Albania culminating with the Mw = 6.4 event of 26 November 2019 was examined from the geodetic (InSAR and GNSS), structural, and historical viewpoints, with some ideas on possible areas of greater hazard. We present accurate estimates of the coseismic displacements using permanent GNSS stations active before and after the sequence, as well as SAR interferograms with Sentinel-1 in ascending and descending mode. When compared with the displacements predicted by a dislocation model on an elastic half space using the moment tensor information of a reverse fault mechanism, the InSAR and GNSS data fit at the mm level provided the hypocentral depth is set to 8 ± 2 km. Next, we examined the elastic stress generated by the Mw = 7.2 Montenegro earthquake of 1979, with the Albania 2019 event as receiver fault, to conclude that the Coulomb stress transfer, at least for the elastic component, was too small to have influenced the 2019 Albania event. A somewhat different picture emerges from the combined elastic deformation resulting after the two (1979 and 2019) events: we investigated the fault geometries where the Coulomb stress is maximized and concluded that the geometry with highest induced Coulomb stress, of the order of ca. 2–3 bar (0.2–0.3 MPa), is that of a vertical, dextral strike slip fault, striking SW to NE. This optimal receiver fault is located between the faults activated in 1979 and 2019, and very closely resembles the Lezhe fault, which marks the transition between the Dinarides and the Albanides. Full article

(This article belongs to the Special Issue Ground Deformation Patterns Detection by InSAR and GNSS Techniques)

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