Improving InSAR geodesy using global atmospheric models

Spatial and temporal variations of pressure, temperature and water vapor content in the atmosphere introduce significant confounding delays in Interferometric Synthetic Aperture Radar (InSAR) observations of ground deformation and bias estimatesof regional strain rates. Producing robust estimates of tropospheric delays remains one of the key challenges in increasing the accuracy of ground deformation measurements using InSAR. Recent studies revealed the efficiency of global atmospheric reanalysis to mitigate the impact of tropospheric delays, motivating further exploration of their potential. Here, we explore the effectiveness of these models in several geographic and tectonic settings on both single interferograms and time series analysis products. Both hydrostatic and wet contributions to the phase delay are important to account for. We validate these path delay corrections by comparing with estimates of vertically integrated atmospheric water vapor content derived from the passive multi-spectral imager MERIS, onboard the ENVISAT satellite. Generally, the performance of the prediction depends on the vigor of atmospheric turbulence. We discuss (1) how separating atmospheric and orbital contributions allows one to better measure long wavelength deformation, (2) how atmospheric delays affect measurements of surface deformation following earthquakes and (3) we show that such a method allows us to reduce biases in multi-year strain rate estimates by reducing the influence of unevenly sampled seasonal oscillations of the tropospheric delay

25 years of satellite InSAR monitoring of ground instability and coastal geohazards in the archaeological site of Capo Colonna, Italy

For centuries the promontory of Capo Colonna in Calabria region, southern Italy, experienced land subsidence and coastline retreat to an extent that the archaeological ruins of the ancient Greek sanctuary are currently under threat of cliff failure, toppling and irreversible loss. Gas extraction in nearby wells is a further anthropogenic element to account for at the regional scale. Exploiting an unprecedented satellite Synthetic Aperture Radar (SAR) time series including ERS-1/2, ENVISAT, TerraSAR-X, COSMO-SkyMed and Sentinel-1A data stacks acquired between 1992 and 2016, this paper presents the first and most complete Interferometric SAR (InSAR) baseline assessment of land subsidence and coastal processes affecting Capo Colonna. We analyse the regional displacement trends, the correlation between vertical displacements with gas extraction volumes, the impact on stability of the archaeological heritage, and the coastal geohazard susceptibility. In the last 25 years, the land has subsided uninterruptedly, with highest annual line-of-sight deformation rates ranging between -15 and -20 mm/year in 2011-2014. The installation of 40 pairs of corner reflectors along the northern coastline and within the archaeological park resulted in an improved imaging capability and higher density of measurement points. This proved to be beneficial for the ground stability assessment of recent archaeological excavations, in an area where field surveying in November 2015 highlighted new events of cliff failure. The conceptual model developed suggests that combining InSAR results, geomorphological assessments and inventorying of wave-storms will contribute to unveil the complexity of coastal geohazards in Capo Colonna. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

InSAR Monitoring of Italian Coastline Revealing Natural and Anthropogenic Ground Deformation Phenomena and Future Perspectives

In this work, we use X and C-band SAR data provided by the COSMO-SkyMed and ENVISAT missions to detect and measure some ground deformation phenomena along six coastal areas of Italy. In particular, we exploit multi-temporal interferometric synthetic aperture radar (InSAR), i.e., small baseline subsets (SBAS) and interferometric point target analysis (IPTA) methods, to retrieve the deformation rate maps and time series for each investigated area. Multi-temporal InSAR analysis revealed local subsidence and uplifting effects in Ravenna Coastal Areas, Fiumicino, Campi Flegrei, Sibari Plain, Augusta Bay, and Taranto Gulf. Our work is meant as a demonstrator to show how InSAR-based analysis can provide a detailed understanding of the coastal hazards. Such analysis also opens up new monitoring scenarios such as the possibility of designing a near real-time surveillance service based on Sentinel-1 SAR data.Publishedid 31522T. Deformazione crostale attivaJCR Journa

Source model of the 2007 M_w 8.0 Pisco, Peru earthquake: Implications for seismogenic behavior of subduction megathrusts

We use Interferometric Synthetic Aperture Radar, teleseismic body waves, tsunami waveforms recorded by tsunameters, field observations of coastal uplift, subsidence, and runup to develop and test a refined model of the spatiotemporal history of slip during the M_w 8.0 Pisco earthquake of 15 August 2007. Our preferred solution shows two distinct patches of high slip. One patch is located near the epicenter while another larger patch ruptured 60 km further south, at the latitude of the Paracas peninsula. Slip on the second patch started 60 s after slip initiated on the first patch. We observed a remarkable anticorrelation between the coseismic slip distribution and the aftershock distribution determined from the Peruvian seismic network. The proposed source model is compatible with regional runup measurements and open ocean tsunami records. From the latter data set, we identified the 12 min timing error of the tsunami forecast system as being due to a mislocation of the source, caused by the use of only one tsunameter located in a nonoptimal azimuth. The comparison of our source model with the tsunami observations validate that the rupture did not extend to the trench and confirms that the Pisco event is not a tsunami earthquake despite its low apparent rupture velocity (<1.5 km/s). We favor the interpretation that the earthquake consists of two subevents, each with a conventional rupture velocity (2–4 km/s). The delay between the two subevents might reflect the time for the second shock to nucleate or, alternatively, the time it took for afterslip to increase the stress level on the second asperity to a level necessary for static triggering. The source model predicts uplift offshore and subsidence on land with the pivot line following closely the coastline. This pattern is consistent with our observation of very small vertical displacement along the shoreline when we visited the epicentral area in the days following the event. This earthquake represents, to our knowledge, one of the best examples of a link between the geomorphology of the coastline and the pattern of surface deformation induced by large interplate ruptures

Land subsidence over oilfields in the Yellow River Delta

Subsidence in river deltas is a complex process that has both natural and human causes. Increasing human activities like aquaculture and petroleum extraction are affecting the Yellow River delta, and one consequence is subsidence. The purpose of this study is to measure the surface displacements in the Yellow River delta region and to investigate the corresponding subsidence source. In this paper, the Stanford Method for Persistent Scatterers (StaMPS) package was employed to process Envisat ASAR images collected between 2007 and 2010. Consistent results between two descending tracks show subsidence with a mean rate up to 30 mm/yr in the radar line of sight direction in Gudao Town (oilfield), Gudong oilfield and Xianhe Town of the delta, each of which is within the delta, and also show that subsidence is not uniform across the delta. Field investigation shows a connection between areas of non-uniform subsidence and of petroleum extraction. In a 9 km2 area of the Gudao Oilfield, a poroelastic disk reservoir model is used to model the InSAR derived displacements. In general, good fits between InSAR observations and modeled displacements are seen. The subsidence observed in the vicinity of the oilfield is thus suggested to be caused by fluid extraction

Seven years of postseismic deformation following the 2003 Mw = 6.8 Zemmouri earthquake (Algeria) from InSAR time series

International audience[1] We study the postseismic surface deformation of the Mw 6.8, 2003 Zemmouri earthquake (northern Algeria) using the Multi-Temporal Small Baseline InSAR technique. InSAR time series obtained from 31 Envisat ASAR images from 2003 to 2010 reveal sub-cm coastline ground movements between Cap Matifou and Dellys. Two regions display subsidence at a maximum rate of 2 mm/yr in Cap Djenet and 3.5 mm/yr in Boumerdes. These regions correlate well with areas of maximum coseismic uplifts, and their association with two rupture segments. Inverse modeling suggest that subsidence in the areas of high coseismic uplift can be explained by afterslip on shallow sections (<5 km) of the fault above the areas of coseismic slip, in agreement with previous GPS observations. The earthquake impact on soft sediments and the ground water table southwest of the earthquake area, characterizes ground deformation of non-tectonic origin. The cumulative postseismic moment due to 7 years afterslip is equivalent to an Mw 6.3 earthquake. Therefore, the postseismic deformation and stress buildup has significant implications on the earthquake cycle models and recurrence intervals of large earthquakes in the Algiers area

INSAR Principles B

reserved5A. Ferretti; A. Monti Guarnieri; C. Prati; F. Rocca; D. MassonnetFerretti, Alessandro; MONTI-GUARNIERI, ANDREA VIRGILIO; Prati, CLAUDIO MARIA; Rocca, Fabio; D., Massonne

Advanced Geoscience Remote Sensing

Nowadays, advanced remote sensing technology plays tremendous roles to build a quantitative and comprehensive understanding of how the Earth system operates. The advanced remote sensing technology is also used widely to monitor and survey the natural disasters and man-made pollution. Besides, telecommunication is considered as precise advanced remote sensing technology tool. Indeed precise usages of remote sensing and telecommunication without a comprehensive understanding of mathematics and physics. This book has three parts (i) microwave remote sensing applications, (ii) nuclear, geophysics and telecommunication; and (iii) environment remote sensing investigations