Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)

We present in this comment a Multi-Temporal SAR Interferometry (MT-InSAR) analysis showing that the results published by Milillo et al. (2019) in the Remote Sensing Journal, presenting the evidence of space geodetic observations relevant to displacements occurring before the collapse of the Morandi...

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Main Authors: Riccardo Lanari, Diego Reale, Manuela Bonano, Simona Verde, Yasir Muhammad, Gianfranco Fornaro, Francesco Casu, Michele Manunta
Format: Article
Language:English
Published: MDPI AG 2020-12-01
Series:Remote Sensing
Subjects:
Online Access:https://www.mdpi.com/2072-4292/12/24/4011
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author Riccardo Lanari
Diego Reale
Manuela Bonano
Simona Verde
Yasir Muhammad
Gianfranco Fornaro
Francesco Casu
Michele Manunta
author_facet Riccardo Lanari
Diego Reale
Manuela Bonano
Simona Verde
Yasir Muhammad
Gianfranco Fornaro
Francesco Casu
Michele Manunta
author_sort Riccardo Lanari
collection DOAJ
description We present in this comment a Multi-Temporal SAR Interferometry (MT-InSAR) analysis showing that the results published by Milillo et al. (2019) in the Remote Sensing Journal, presenting the evidence of space geodetic observations relevant to displacements occurring before the collapse of the Morandi Bridge, happened in Genova (Italy) on the 14 August 2018, are questionable. In particular, we focus on the InSAR results obtained by Milillo et al. (2019) by processing the 3 m × 3 m resolution COSMO-SkyMed (CSK) data collected from ascending and descending orbits on the area of interest. These results, thanks to the high spatial resolution and the short revisit time characterizing this multi-orbit SAR dataset, represent the cornerstone of their analysis. The main findings of their study allow Milillo et al. to conclude that the InSAR processing of this COSMO-SkyMed dataset reveals the increased deformation magnitude over time of points located near the strands of the deck next to the collapsed pier, between 12 March 2017 and August 2018. In this comment, we show the results obtained by the IREA-CNR SAR team after processing the same ascending and descending CSK dataset, but by using two alternative and independent processing techniques: the Small BAseline Subset (SBAS) and the Advanced Tomographic SAR (TomoSAR) approaches, respectively. Our analysis shows that, although both the SBAS and the TomoSAR analyses allow achieving denser coherent pixel maps relevant to the Morandi bridge, nothing of the pre-collapse large displacements reported in Milillo et al. (2019) appears in our results, leading us to deeply disagree with the findings of their InSAR analysis.
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spelling doaj.art-306f945b0a4a4672a6192199a24506d82023-11-20T23:52:36ZengMDPI AGRemote Sensing2072-42922020-12-011224401110.3390/rs12244011Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)Riccardo Lanari0Diego Reale1Manuela Bonano2Simona Verde3Yasir Muhammad4Gianfranco Fornaro5Francesco Casu6Michele Manunta7Institute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyInstitute for the Electromagnetic Sensing of the Environment—National Research Council (IREA-CNR), Via Diocleziano 328, 80124 Naples, ItalyWe present in this comment a Multi-Temporal SAR Interferometry (MT-InSAR) analysis showing that the results published by Milillo et al. (2019) in the Remote Sensing Journal, presenting the evidence of space geodetic observations relevant to displacements occurring before the collapse of the Morandi Bridge, happened in Genova (Italy) on the 14 August 2018, are questionable. In particular, we focus on the InSAR results obtained by Milillo et al. (2019) by processing the 3 m × 3 m resolution COSMO-SkyMed (CSK) data collected from ascending and descending orbits on the area of interest. These results, thanks to the high spatial resolution and the short revisit time characterizing this multi-orbit SAR dataset, represent the cornerstone of their analysis. The main findings of their study allow Milillo et al. to conclude that the InSAR processing of this COSMO-SkyMed dataset reveals the increased deformation magnitude over time of points located near the strands of the deck next to the collapsed pier, between 12 March 2017 and August 2018. In this comment, we show the results obtained by the IREA-CNR SAR team after processing the same ascending and descending CSK dataset, but by using two alternative and independent processing techniques: the Small BAseline Subset (SBAS) and the Advanced Tomographic SAR (TomoSAR) approaches, respectively. Our analysis shows that, although both the SBAS and the TomoSAR analyses allow achieving denser coherent pixel maps relevant to the Morandi bridge, nothing of the pre-collapse large displacements reported in Milillo et al. (2019) appears in our results, leading us to deeply disagree with the findings of their InSAR analysis.https://www.mdpi.com/2072-4292/12/24/4011bridge collapseinfrastructures monitoringInSARdeformation time seriesSBASTomoSAR
spellingShingle Riccardo Lanari
Diego Reale
Manuela Bonano
Simona Verde
Yasir Muhammad
Gianfranco Fornaro
Francesco Casu
Michele Manunta
Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
Remote Sensing
bridge collapse
infrastructures monitoring
InSAR
deformation time series
SBAS
TomoSAR
title Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
title_full Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
title_fullStr Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
title_full_unstemmed Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
title_short Comment on “Pre-Collapse Space Geodetic Observations of Critical Infrastructure: The Morandi Bridge, Genoa, Italy” by Milillo et al. (2019)
title_sort comment on pre collapse space geodetic observations of critical infrastructure the morandi bridge genoa italy by milillo et al 2019
topic bridge collapse
infrastructures monitoring
InSAR
deformation time series
SBAS
TomoSAR
url https://www.mdpi.com/2072-4292/12/24/4011
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