Remote Sensing

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13 pages, 31129 KiB

Open AccessFeature PaperArticle

Source Parameter Estimation of the 2009 Ms6.0 Yao’an Earthquake, Southern China, Using InSAR Observations

by Wei Qu, Bing Zhang, Zhong Lu, Jin Woo Kim, Qin Zhang, Yuan Gao, Ming Hao, Wu Zhu and Feifei Qu

Remote Sens. 2019, 11(4), 462; https://doi.org/10.3390/rs11040462 - 23 Feb 2019

Cited by 8 | Viewed by 3939

Abstract

On 9 July 2009, an Ms6.0 earthquake occurred in mountainous area of Yao’an in Yunnan province of Southern China. Although the magnitude of the earthquake was moderate, it attracted the attention of many Earth scientists because of its threat to the safety of [...] Read more.

On 9 July 2009, an Ms6.0 earthquake occurred in mountainous area of Yao’an in Yunnan province of Southern China. Although the magnitude of the earthquake was moderate, it attracted the attention of many Earth scientists because of its threat to the safety of the population and its harm to the local economy. However, the source parameters remain poorly understood due to the sparse distribution of seismic and GNSS (Global Navigation Satellite System) stations in this mountainous region. Therefore, in this study, the two L-band ALOS (Advanced Land Observing Satellite-1) PALSAR (Phased Array type L-band Synthetic Aperture Radar) images from an ascending track is used to investigate the coseismic deformation field, and further determine the location, fault geometry and slip distribution of the earthquake. The results show that the Yao’an earthquake was a strike-slip event with a down-dip slip component. The slip mainly occurred at depths of 3–8 km, with a maximum slip of approximately 70 cm at a depth of 6 km, which is shallower than the reported focal depth of ~10 km. An analysis of the seismic activity and tectonics of the Yao’an area reveals that the 9 July 2009 Yao’an earthquake was the result of regional stress accumulation, which eventually led to the rupture of the northwestern most part of the Maweijing fault. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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16 pages, 11368 KiB

Open AccessArticle

A Fine Velocity and Strain Rate Field of Present-Day Crustal Motion of the Northeastern Tibetan Plateau Inverted Jointly by InSAR and GPS

by Xiaogang Song, Yu Jiang, Xinjian Shan, Wenyu Gong and Chunyan Qu

Remote Sens. 2019, 11(4), 435; https://doi.org/10.3390/rs11040435 - 20 Feb 2019

Cited by 29 | Viewed by 4515

Abstract

Interferometric synthetic aperture radar (InSAR) data from 6 Envisat ASAR descending tracks; spanning the 2003–2010 period; was used to measure interseismic strain accumulation across the Northeastern Tibetan Plateau. Mean line-of-sight (LOS) ratemaps are computed by stacking atmospheric-corrected and orbital-corrected interferograms. The ratemaps from [...] Read more.

Interferometric synthetic aperture radar (InSAR) data from 6 Envisat ASAR descending tracks; spanning the 2003–2010 period; was used to measure interseismic strain accumulation across the Northeastern Tibetan Plateau. Mean line-of-sight (LOS) ratemaps are computed by stacking atmospheric-corrected and orbital-corrected interferograms. The ratemaps from one track with different atmospheric-corrected results or two parallel; partially overlapping tracks; show a consistent pattern of left-lateral motion across the fault; which demonstrates the MERIS and ECMWF atmospheric correction works satisfactorily for small stain measurement of this region; even with a limited number of interferograms. By combining the measurements of InSAR and GPS; a fine crustal deformation velocity and strain rate field was estimated on discrete points with irregular density depending on the fault location; which revealed that the present-day slip rate on the Haiyuan fault system varies little from west to east. A change (2–3 mm/year) in line-of-sight (LOS) deformation rate across the fault is observed from the Jinqianghe segment to its eastern end. Inversion from the cross-fault InSAR profiles gave a shallow locking depth of 3–6 km on the main rupture of the 1920 earthquake. We therefore infer that the middle-lower part of the seismogenic layer on the 1920 rupture is not yet fully locked since the 1920 large earthquake. Benefit from high spatial resolution InSAR data; a low strain accumulation zone with high strain rates on its two ends was detected; which corresponds to the creeping segment; i.e., the Laohushan fault segment. Contrary to the previous knowledge of squeezing structure; an abnormal tension zone is disclosed from the direction map of principal stress; which is consistent with the recent geological study. The distribution of principal stress also showed that the expanding frontier of the northeastern plateau has crossed the Liupan Shan fault zone; even arrived at the northeast area of the Xiaoguan Shan. This result agrees with the deep seismic reflection profile. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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17 pages, 25837 KiB

Open AccessArticle

Co- and post-seismic Deformation Mechanisms of the M_W 7.3 Iran Earthquake (2017) Revealed by Sentinel-1 InSAR Observations

by Chengsheng Yang, Bingquan Han, Chaoying Zhao, Jiantao Du, Dongxiao Zhang and Sainan Zhu

Remote Sens. 2019, 11(4), 418; https://doi.org/10.3390/rs11040418 - 18 Feb 2019

Cited by 22 | Viewed by 5329

Abstract

The extraction of high-accuracy co- and post-seismic deformation fields and inversions of seismic slip distributions is significant in the comprehension of seismogenic mechanisms. On 12 November 2017, a M_W 7.3 earthquake occurred on the border between Iran and Iraq. To construct the [...] Read more.

The extraction of high-accuracy co- and post-seismic deformation fields and inversions of seismic slip distributions is significant in the comprehension of seismogenic mechanisms. On 12 November 2017, a M_W 7.3 earthquake occurred on the border between Iran and Iraq. To construct the co-seismic deformation field, Sentinel-1A synthetic aperture radar (SAR) images from three tracks were used. Based on a prior knowledge, least-squares iterative approximation was employed to construct the three-dimensional (3D) co-seismic deformation field. to derive a time series of 2D post-seismic deformation, the multidimensional small baseline subset (MSBAS) technique was use. Co-seismic deformation fields were asymmetric; the maximum relative displacement was nearly 90cm in the radar line-of-sight between two centers of co-seismic deformation. The 3D co-seismic deformation field showed southwestward horizontal motion and continuous subsidence-to-uplift variation from northeast to southwest. The two-dimensional (2D) post-seismic deformation time series showed a gradual decaying trend and good correspondence with the aftershock distribution. The main mechanism of post-seismic deformation was an afterslip of the post-seismic faults. We used the elastic half-space model to invert co-seismic deformation fields and obtain source parameters of the slip model. The maximum and average slips were 2.5 and 0.72 m, respectively. The average slip angle was 126.38° and the moment magnitude was M_W 7.34. The results of this study will contribute to research on regional tectonic activities. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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21 pages, 9628 KiB

Open AccessArticle

Crustal Deformation on the Northeastern Margin of the Tibetan Plateau from Continuous GPS Observations

by Xiaoning Su, Lianbi Yao, Weiwei Wu, Guojie Meng, Lina Su, Renwei Xiong and Shunying Hong

Remote Sens. 2019, 11(1), 34; https://doi.org/10.3390/rs11010034 - 26 Dec 2018

Cited by 47 | Viewed by 4766

Abstract

We installed 10 continuous Global Positioning System (GPS) stations on the northeast margin of the Tibetan Plateau at the end of 2012, in order to qualitatively investigate strain accumulation across the Liupanshan Fault (LPSF). We integrated our newly built stations with 48 other [...] Read more.

We installed 10 continuous Global Positioning System (GPS) stations on the northeast margin of the Tibetan Plateau at the end of 2012, in order to qualitatively investigate strain accumulation across the Liupanshan Fault (LPSF). We integrated our newly built stations with 48 other existing GPS stations to provide new insights into three-dimensional tectonic deformation. We employed white plus flicker noise model as a statistical model to obtain realistic velocities and corresponding uncertainties in the ITRF2014 and Ordos-fixed reference frame. The total velocity decrease from northwest to southeast in the Longxi Block (LXB) was 5.3 mm/yr within the range of 200 km west of the LPSF on the horizontal component. The first-order characteristic of the vertical crustal deformation was uplift for the northeastern margin of the Tibetan Plateau. The uplift rates in the LXB and the Ordos Block (ORB) were 1.0 and 2.0 mm/yr, respectively. We adopted an improved spherical wavelet algorithm to invert for multiscale strain rates and rotation rates. Multiscale strain rates showed a complex crustal deformation pattern. A significant clockwise rotation of about 30 nradians/yr (10⁻⁹ radians/year) was identified around the Dingxi. Localized strain accumulation was determined around the intersectional region between the Haiyuan Fault (HYF) and the LPSF. The deformation pattern across the LFPS was similar to that of the Longmengshan Fault (LMSF) before the 2008 Wenchuan M_S 8.0 earthquake. Furthermore, according to the distributed second invariant of strain rates at different spatial scale, strain partitioning has already spatially localized along the Xiaokou–Liupanshan–Longxian–Baoji fault belt (XLLBF). The tectonic deformation and localized strain buildup together with seismicity imply a high probability for a potential earthquake in this zone. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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19 pages, 7519 KiB

Open AccessArticle

Crustal Deformation Prior to the 2017 Jiuzhaigou, Northeastern Tibetan Plateau (China), Ms 7.0 Earthquake Derived from GPS Observations

by Weiwei Wu, Xiaoning Su, Guojie Meng and Chentao Li

Remote Sens. 2018, 10(12), 2028; https://doi.org/10.3390/rs10122028 - 13 Dec 2018

Cited by 6 | Viewed by 3633

Abstract

The 2017 Jiuzhaigou Ms 7.0 earthquake occurred on the northeastern margin of the Tibetan Plateau, with no noticeable rupture surface recognized. We characterized the pre-seismic deformation of the earthquake from GPS (Global Positioning System) data at eight continuous and 73 campaign sites acquired [...] Read more.

The 2017 Jiuzhaigou Ms 7.0 earthquake occurred on the northeastern margin of the Tibetan Plateau, with no noticeable rupture surface recognized. We characterized the pre-seismic deformation of the earthquake from GPS (Global Positioning System) data at eight continuous and 73 campaign sites acquired over the 2009–2017 period. With respect to the Eurasian plate, the velocity field showed a noticeable decrease, from west of the epicenter of the Jiuzhaigou earthquake to the western edge of the Longmenshan fault, in the southeast direction. The total northwest west–southeast east shortening rate in the vicinity of the epicentral area was in the range of 1.5 mm/y to 3.1 mm/y. With a GPS velocity transect across the Huya fault (HYF), where the epicenter was located, we estimated the activity of the HYF, showing a dominant left-lateral slip rate of 3.3 ± 0.2 mm/y. We calculated strain rates using a spherical wavelet-based multiscale approach that solved for the surface GPS velocity according to multiscale wavelet basis functions while accounting for spatially variable spacing of observations. Multiscale components of the two-dimensional strain rate tensor showed a complex crustal deformation pattern. Our estimates of strain rate components at the scale of seven and eight revealed extensional strain rate on the northern extension of the HYF. The Jiuzhaigou earthquake occurred at the buffer zone between extensional and compressional deformation, and with significant maximum shear rates being 100–140 nanostrain/y. In addition, a maximum shear strain rate of 60–120 nanostrain/y appeared around the epicenter of the 2013 Ms 6.6 Minxian–Zhangxian earthquake. These findings imply that inherent multiscale strain rates could be separated to identify strain accumulation related to medium- and large-sized earthquakes. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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29 pages, 14619 KiB

Open AccessArticle

Spatiotemporal Evolution of Postseismic Deformation Following the 2001 Mw7.8 Kokoxili, China, Earthquake from 7 Years of Insar Observations

by Dezheng Zhao, Chunyan Qu, Xinjian Shan, Roland Bürgmann, Wenyu Gong and Guohong Zhang

Remote Sens. 2018, 10(12), 1988; https://doi.org/10.3390/rs10121988 - 8 Dec 2018

Cited by 14 | Viewed by 3300

Abstract

The 2001 Mw7.8 Kokoxili earthquake, which occurred in the north Tibetan Plateau, ruptured ~400 km of the westernmost portion of the Kunlun fault and produced significant time-dependent postseismic deformation over a large area around the rupture zone and nearby regions. To analyze the [...] Read more.

The 2001 Mw7.8 Kokoxili earthquake, which occurred in the north Tibetan Plateau, ruptured ~400 km of the westernmost portion of the Kunlun fault and produced significant time-dependent postseismic deformation over a large area around the rupture zone and nearby regions. To analyze the postseismic deformation features along different sections of the coseismic surface rupture, we describe the total cumulative postseismic deformation near the center of the rupture and produce velocity maps for the whole observation period and six sub-periods, using InSAR observations (ENVISAT/ASAR, 2003–2010) on five descending tracks. The results indicate that the postseismic deformation is asymmetrically distributed across the fault over a very broad area of ~300 km × 500 km. The south side of the fault exhibits larger displacements and a wider area of deformation that is steadily decaying from near-field to far-field, while the north side displays a narrow, rapidly diminishing deformation field. The maximum cumulative displacement in 2003–2010 reaches up to ~45–60 mm and the LOS peak-to-trough average velocity offset in 2003–2010 reaches ~13–16 mm/yr at ~92.5°E. The short-term postseismic velocity estimates in the six sub-periods reflect significant spatial variation and temporal differences on different sections. Motions to the south of the two ends of the rupture zone show more rapid velocity decay compared to near the main central rupture zone. The time- and distance-dependent timeseries of postseismic surface displacement reveal exponential decay in the near-field and a nearly linear trend in the far-field of the fault. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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19 pages, 9982 KiB

Open AccessArticle

Ground Deformation and Source Geometry of the 30 October 2016 M_w 6.5 Norcia Earthquake (Central Italy) Investigated Through Seismological Data, DInSAR Measurements, and Numerical Modelling

by Emanuela Valerio, Pietro Tizzani, Eugenio Carminati, Carlo Doglioni, Susi Pepe, Patrizio Petricca, Claudio De Luca, Christian Bignami, Giuseppe Solaro, Raffaele Castaldo, Vincenzo De Novellis and Riccardo Lanari

Remote Sens. 2018, 10(12), 1901; https://doi.org/10.3390/rs10121901 - 28 Nov 2018

Cited by 28 | Viewed by 3832

Abstract

We investigate the M_w 6.5 Norcia (Central Italy) earthquake by exploiting seismological data, DInSAR measurements, and a numerical modelling approach. In particular, we first retrieve the vertical component (uplift and subsidence) of the displacements affecting the hangingwall and the footwall blocks of [...] Read more.

We investigate the M_w 6.5 Norcia (Central Italy) earthquake by exploiting seismological data, DInSAR measurements, and a numerical modelling approach. In particular, we first retrieve the vertical component (uplift and subsidence) of the displacements affecting the hangingwall and the footwall blocks of the seismogenic faults identified, at depth, through the hypocenters distribution analysis. To do this, we combine the DInSAR measurements obtained from coseismic SAR data pairs collected by the ALOS-2 sensor from ascending and descending orbits. The achieved vertical deformation map displays three main deformation patterns: (i) a major subsidence that reaches the maximum value of about 98 cm near the epicentral zones nearby the town of Norcia; (ii) two smaller uplift lobes that affect both the hangingwall (reaching maximum values of about 14 cm) and the footwall blocks (reaching maximum values of about 10 cm). Starting from this evidence, we compute the rock volumes affected by uplift and subsidence phenomena, highlighting that those involved by the retrieved subsidence are characterized by significantly higher deformation values than those affected by uplift (about 14 times). In order to provide a possible interpretation of this volumetric asymmetry, we extend our analysis by applying a 2D numerical modelling approach based on the finite element method, implemented in a structural-mechanic framework, and exploiting the available geological and seismological data, and the ground deformation measurements retrieved from the multi-orbit ALOS-2 DInSAR analysis. In this case, we consider two different scenarios: the first one based on a single SW-dipping fault, the latter on a main SW-dipping fault and an antithetic zone. In this context, the model characterized by the occurrence of an antithetic zone presents the retrieved best fit coseismic surface deformation pattern. This result allows us to interpret the subsidence and uplift phenomena caused by the M_w 6.5 Norcia earthquake as the result of the gravitational sliding of the hangingwall along the main fault plane and the frictional force acting in the opposite direction, consistently with the double couple fault plane mechanism. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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31 pages, 16534 KiB

Open AccessArticle

Effects of Spatiotemporal Filtering on the Periodic Signals and Noise in the GPS Position Time Series of the Crustal Movement Observation Network of China

by Peng Yuan, Weiping Jiang, Kaihua Wang and Nico Sneeuw

Remote Sens. 2018, 10(9), 1472; https://doi.org/10.3390/rs10091472 - 14 Sep 2018

Cited by 24 | Viewed by 4935

Abstract

Analysis of Global Positioning System (GPS) position time series and its common mode components (CMC) is very important for the investigation of GPS technique error, the evaluation of environmental loading effects, and the estimation of a realistic and unbiased GPS velocity field for [...] Read more.

Analysis of Global Positioning System (GPS) position time series and its common mode components (CMC) is very important for the investigation of GPS technique error, the evaluation of environmental loading effects, and the estimation of a realistic and unbiased GPS velocity field for geodynamic applications. In this paper, we homogeneously processed the daily observations of 231 Crustal Movement Observation Network of China (CMONOC) Continuous GPS stations to obtain their position time series. Then, we filtered out the CMC and evaluated its effects on the periodic signals and noise for the CMONOC time series. Results show that, with CMC filtering, peaks in the stacked power spectra can be reduced at draconitic harmonics up to the 14th, supporting the point that the draconitic signal is spatially correlated. With the colored noise suppressed by CMC filtering, the velocity uncertainty estimates for both of the two subnetworks, CMONOC-I (≈16.5 years) and CMONOC-II (≈4.6 years), are reduced significantly. However, the CMONOC-II stations obtain greater reduction ratios in velocity uncertainty estimates with average values of 33%, 38%, and 54% for the north, east, and up components. These results indicate that CMC filtering can suppress the colored noise amplitudes and improve the precision of velocity estimates. Therefore, a unified, realistic, and three-dimensional CMONOC GPS velocity field estimated with the consideration of colored noise is given. Furthermore, contributions of environmental loading to the vertical CMC are also investigated and discussed. We find that the vertical CMC are reduced at 224 of the 231 CMONOC stations and 170 of them are with a root mean square (RMS) reduction ratio of CMC larger than 10%, confirming that environmental loading is one of the sources of CMC for the CMONOC height time series. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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11 pages, 4073 KiB

Open AccessArticle

The Locking Depth of the Cholame Section of the San Andreas Fault from ERS2-Envisat InSAR

by Guillaume Bacques, Marcello De Michele, Daniel Raucoules and Hideo Aochi

Remote Sens. 2018, 10(8), 1244; https://doi.org/10.3390/rs10081244 - 7 Aug 2018

Cited by 1 | Viewed by 5604

Abstract

The Cholame section of the San Andreas Fault (SAF), which has been considered locked since 1857, has been little studied using geodetic methods. In this study, we propose to use Interferometric Synthetic Aperture Radar (InSAR) to contribute to the improvement of the knowledge [...] Read more.

The Cholame section of the San Andreas Fault (SAF), which has been considered locked since 1857, has been little studied using geodetic methods. In this study, we propose to use Interferometric Synthetic Aperture Radar (InSAR) to contribute to the improvement of the knowledge of this section of the SAF. In particular, the objective of this work is to provide a description of the transition between the Parkfield and Cholame-Carrizo segments further southeast by producing an estimate of the locking depth of the Cholame segment by combining ERS2 (European Remote Sensing) and Envisat Advanced SAR (ASAR) satellites data. Our results indicate that the locking depth between the Parkfield and the Cholame-Carrizo segments deepens to the southeast. We then use these results as a hint to refine the tectonic loading on this section of the SAF. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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20 pages, 4745 KiB

Open AccessArticle

The Use of Massive Deformation Datasets for the Analysis of Spatial and Temporal Evolution of Mauna Loa Volcano (Hawai’i)

by Susi Pepe, Luca D’Auria, Raffaele Castaldo, Francesco Casu, Claudio De Luca, Vincenzo De Novellis, Eugenio Sansosti, Giuseppe Solaro and Pietro Tizzani

Remote Sens. 2018, 10(6), 968; https://doi.org/10.3390/rs10060968 - 17 Jun 2018

Cited by 12 | Viewed by 6443

Abstract

In this work, we exploited large DInSAR and GPS datasets to create a 4D image of the magma transfer processes at Mauna Loa Volcano (Island of Hawai’i) from 2005 to 2015. The datasets consist of 23 continuous GPS time series and 307 SAR [...] Read more.

In this work, we exploited large DInSAR and GPS datasets to create a 4D image of the magma transfer processes at Mauna Loa Volcano (Island of Hawai’i) from 2005 to 2015. The datasets consist of 23 continuous GPS time series and 307 SAR images acquired from ascending and descending orbits by ENVISAT (ENV) and COSMO-SkyMed (CSK) satellites. Our results highlight how the joint use of SAR data acquired from different orbits (thus with different look angles and wavelengths), together with deformation data from GPS networks and geological information can significantly improve the constraints on the geometry and location of the sources responsible for the observed deformation. The analysis of these datasets has been performed by using an innovative method that allows building a complex source configuration. The results suggest that the deformation pattern observed from 2005 to 2015 has been controlled by three deformation sources: the ascent of magma along a conduit, the opening of a dike and the slip along the basal decollement. This confirms that the intrusion of the magma within a tabular system (rift dikes) may trigger the sliding of the SE portion of the volcanic edifice along the basal decollement. This case study confirms that it is now possible to exploit large geodetic datasets to improve our knowledge of volcano dynamics. The same approach could also be easily applied in other geodynamical contexts such as geothermal reservoirs and regions with complex tectonics. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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19 pages, 7228 KiB

Open AccessArticle

Influences of Environmental Loading Corrections on the Nonlinear Variations and Velocity Uncertainties for the Reprocessed Global Positioning System Height Time Series of the Crustal Movement Observation Network of China

by Peng Yuan, Zhao Li, Weiping Jiang, Yifang Ma, Wu Chen and Nico Sneeuw

Remote Sens. 2018, 10(6), 958; https://doi.org/10.3390/rs10060958 - 15 Jun 2018

Cited by 22 | Viewed by 4898

Abstract

Mass redistribution of the atmosphere, oceans, and terrestrial water storage generates crustal displacements which can be predicted by environmental loading models and observed by the Global Positioning System (GPS). In this paper, daily height time series of 235 GPS stations derived from a [...] Read more.

Mass redistribution of the atmosphere, oceans, and terrestrial water storage generates crustal displacements which can be predicted by environmental loading models and observed by the Global Positioning System (GPS). In this paper, daily height time series of 235 GPS stations derived from a homogeneously reprocessed Crustal Movement Observation Network of China (CMONOC) and corresponding loading displacements predicted by the Deutsche GeoForschungsZentrum (GFZ) are compared to assess the effects of loading corrections on the nonlinear variations of GPS time series. Results show that the average root mean square (RMS) of vertical displacements due to atmospheric, nontidal oceanic, hydrological, and their combined effects are 3.2, 0.6, 2.7, and 4.0 mm, respectively. Vertical annual signals of loading and GPS are consistent in amplitude but different in phase systematically. The average correlation coefficient between loading and GPS height time series is 0.6. RMS of the GPS height time series are reduced by 20% on average. Moreover, an investigation of 208 CMONOC stations with observing time spans of ~4.6 years shows that environmental loading corrections lead to an overestimation of the GPS velocity uncertainty by about 1.4 times on average. Nevertheless, by using a common mode component filter through principal component analysis, the dilution of velocity precision due to environmental loading corrections can be compensated. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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20 pages, 12215 KiB

Open AccessArticle

InSAR-Constrained Interseismic Deformation and Potential Seismogenic Asperities on the Altyn Tagh Fault at 91.5–95°E, Northern Tibetan Plateau

by Chuanjin Liu, Lingyun Ji, Liangyu Zhu and Chaoying Zhao

Remote Sens. 2018, 10(6), 943; https://doi.org/10.3390/rs10060943 - 14 Jun 2018

Cited by 30 | Viewed by 5189

Abstract

The present-day kinematic features of the different segments of the Altyn Tagh Fault (ATF) have been well-studied using geodetic data. However, on the eastern segment of the ATF at 91.5–95°E, high spatial resolution deformation has not been previously reported. Here, we processed 185 [...] Read more.

The present-day kinematic features of the different segments of the Altyn Tagh Fault (ATF) have been well-studied using geodetic data. However, on the eastern segment of the ATF at 91.5–95°E, high spatial resolution deformation has not been previously reported. Here, we processed 185 interferometric synthetic aperture radar (InSAR) images from three descending tracks of the C band ERS-1/2 and Envisat satellites spanning 1995–2011 and obtained the average deformation velocity field. Results show a left-lateral motion of ~4 mm/year along the fault-parallel direction across the ATF at 91.5–95°E, which is consistent with Global Positioning System (GPS) observations. The slip deficit rate distribution at shallow depths was resolved through the InSAR deformation velocity using a discretized fault plane. The slip deficit is capable of an Mw 7.9 earthquake, considering the elapsed time of the latest M 7.0 event. Two potential asperities that could be nucleation sites or rupture areas of future earthquakes were delineated based on the coupling coefficient and seismicity distributions along the fault plane. The larger asperity extends more than 100 km along the ATF at depths of 8–12 km. Our InSAR observations support the undeformed blocks model of the Indo-Eurasian collisional mechanism at the northern margin of the Tibetan plateau. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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24 pages, 12471 KiB

Open AccessArticle

InSAR-Based Mapping to Support Decision-Making after an Earthquake

by Marta Béjar-Pizarro, José A. Álvarez Gómez, Alejandra Staller, Marco P. Luna, Raúl Pérez-López, Oriol Monserrat, Kervin Chunga, Aracely Lima, Jorge Pedro Galve, José J. Martínez Díaz, Rosa María Mateos and Gerardo Herrera

Remote Sens. 2018, 10(6), 899; https://doi.org/10.3390/rs10060899 - 7 Jun 2018

Cited by 21 | Viewed by 7852

Abstract

It has long been recognized that earthquakes change the stress in the upper crust around the fault rupture and can influence the behaviour of neighbouring faults and volcanoes. Rapid estimates of these stress changes can provide the authorities managing the post-disaster situation with [...] Read more.

It has long been recognized that earthquakes change the stress in the upper crust around the fault rupture and can influence the behaviour of neighbouring faults and volcanoes. Rapid estimates of these stress changes can provide the authorities managing the post-disaster situation with valuable data to identify and monitor potential threads and to update the estimates of seismic and volcanic hazard in a region. Here we propose a methodology to evaluate the potential influence of an earthquake on nearby faults and volcanoes and create easy-to-understand maps for decision-making support after large earthquakes. We apply this methodology to the Mw 7.8, 2016 Ecuador earthquake. Using Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) and continuous GPS data, we measure the coseismic ground deformation and estimate the distribution of slip over the fault rupture. We also build an alternative source model using the Global Centroid Moment Tensor (CMT) solution. Then we use these models to evaluate changes of static stress on the surrounding faults and volcanoes and produce maps of potentially activated faults and volcanoes. We found, in general, good agreement between our maps and the seismic and volcanic events that occurred after the Pedernales earthquake. We discuss the potential and limitations of the methodology. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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17 pages, 2676 KiB

Open AccessArticle

Experimental Study of the Thermal Infrared Emissivity Variation of Loaded Rock and Its Significance

by Jianwei Huang, Shanjun Liu, Xiang Gao, Zhengcang Yang, Qiang Ni and Lixin Wu

Remote Sens. 2018, 10(6), 818; https://doi.org/10.3390/rs10060818 - 24 May 2018

Cited by 26 | Viewed by 4978

Abstract

Previous studies have shown that thermal infrared radiation (TIR) changes with stress for loaded rocks. TIR changes were mainly attributed to temperature change without considering the change in surface emissivity. And it remains unclear whether there was a change in emissivity during the [...] Read more.

Previous studies have shown that thermal infrared radiation (TIR) changes with stress for loaded rocks. TIR changes were mainly attributed to temperature change without considering the change in surface emissivity. And it remains unclear whether there was a change in emissivity during the rock loading process. Therefore, based on the spectral radiance observations in this paper, an experimental study involving the emissivity variation in the 8.0–13.0 μm range for elastic loaded quartz sandstone under outdoor conditions was conducted. The experiments yield the following results. First, a variation in the stress condition led to the emissivity change in addition to the temperature change. The spectral radiance change was the combined result of the temperature changes and emissivity changes. Second, the emissivity changes linearly with the stress change, and the amplitude is relatively large in the 8.0–10.0 μm range. The waveband features of emissivity variation are the main factor leading to the waveband features of stress-induced radiance change. Third, the explanations for the changes in temperature and emissivity during loading process are analyzed. And the significance and difficulty for further satellite remote sensing purpose is discussed. The experimental results provide an experimental foundation for crustal stress field monitoring. Full article

(This article belongs to the Special Issue Remote Sensing of Tectonic Deformation)

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