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La Palma, Canary Islands, had its largest historical eruption in 2021. From January 2022 to May 2023 there were >2,100 seismic events, primarily at depths ≤20 km, prompting us to update the deformation and modeling study, using interferometric synthetic aperture radar observations and a last generation interpretation tool. We detect the evolution of the remaining magmatic body in the SW portion of the island, with arrival of new magma moving into the oceanic crust out to sea, and a pressurized zone in the central‐eastern area, at regions of structural weakness. The current source characteristics have some similarities to the early stage dynamics prior to the 2021 eruption. Operational and multidisciplinary studies must continue to monitor either their stabilization or growth and destabilization. The ability to identify magma ascent using only deformation data over short time periods allows us to characterize unrest patterns and provide new insights into volcanic processes. Plain Language Summary: Following the 2021 eruption at La Palma, Canary Islands, seismic activity has persisted that may be a precursor to future volcanic activity. Here we perform an updated deformation and modeling study that characterizes the evolution of the remaining magma in the SW area of the island. A fresh injection of magma occurs in the oceanic crust off the coast, along with a pressurized region in the central‐eastern area of the island where crustal weakness exists close to recent volcanic eruptions. The 2022–2023.4 process has similar characteristics to the evolution prior to the 2021 eruption. Ongoing studies should focus on monitoring the increase or decrease in this activity. Improved characterization of changing volcanic activity over short time periods can provide new insights into ongoing volcanic processes. Key Points: We determine the current unrest is similar to that prior to the 2021 eruption warranting attention by hazard response decision makersWe detect a shallow magmatic intrusion in the SW of the island migrating W into the submarine crust of the islandWe also detect a shallow pressurized zone located in the central eastern region of the island [ABSTRACT FROM AUTHOR]

The Himalayan belt, formed due to Cenozoic convergence between the Eurasia and Indian craton, acts as a storehouse of large amounts of strain that results in large earthquakes that occur from the western to the eastern Himalayas. Glaciers also occur over a major portion of the high-altitude Himalayan region. In this study, we attempt to understand the impact of earthquakes on and around Himalayan glaciers in terms of vertical deformation and coherence change. Eight earthquake events of various magnitudes and hypocenter depths occurring in the vicinity of Himalayan glacial bodies have been analyzed using C-band Sentinel1-A/B synthetic aperture radar (SAR). Differential interferometric SAR (DInSAR) method is applied to the pre-and co-seismic single look complex (SLC) SAR imagery to capture glacial surface deformation potentially related to earthquake occurrence. The influence radius of each earthquake (Mw>4.5) is defined using shake maps. For the lower magnitude earthquakes (Mw<4.5), influence radii are computed using the linear relationship between influence radii and magnitudes of past earthquakes. The mean glacial displacement varies from -38.9 mm to -5.4 mm for the 2020 Tibet earthquake (Mw 5.7) and the 2021 Nepal earthquake (Mw 4.1). However, small glacial and ground patches processed separately for vertical displacements reveal that the glacial mass shows much greater seismic displacement than the ground surface. This indicates potential site-specific seismicity amplification properties of glacial bodies that need additional studies. Reduction in co-seismic coherence around the glaciers is observed in some cases, indicative of possible changes in the glacial moraine deposits and/or vegetation cover. The effect of two different seismic events (the 2020 and 2021 Nepal earthquakes) with different hypocenter depths but the same magnitude at almost equal distances from the glaciers is assessed; a shallow earthquake is observed to result in a larger impact on glacial bodies in terms of vertical displacement. Earthquakes may exacerbate or induce glacial hazards such as glacial surging, ice avalanches, landslides and failure of moraine-/ice-dammed glacial lakes. This research can assist in identifying areas at risk and provide valuable insights for planning and implementing measures for disaster risk reduction in the near future. [ABSTRACT FROM AUTHOR]

La Palma, Canary Islands, underwent volcanic unrest which culminated in its largest historical eruption. We study this unrest along 2021 using Interferometric Synthetic Aperture Radar (InSAR) and a new improved interpretation methodology, comparing achieved results with the crustal structure. We reproduce the final phase of La Palma volcanic unrest, highligthing a shallow magma accumulation which begins about 3.5 months before the eruption in a crustal volume charactherized by low density and fractured rocks. Our modeling, together with our improved pictures of the crustal structure, allows us to explain the location and characteristics of the eruption and to detect failed eruption paths. These can be used to explain post-eruptive phenomena and hazards to the local population, such as detected gases anomalies in La Bombilla and Puerto Naos. Our results have implications for understanding volcanic activity in the Canaries and volcano monitoring elsewhere, helping to support decision-making and providing significant insights into urban and infrastructure planning in volcanic areas. [ABSTRACT FROM AUTHOR]

The increasing number of flood events combined with coastal urbanization has contributed to significant economic losses and damage to buildings and infrastructure. Development of higher resolution SAR flood mapping that accurately identifies flood features at all scales can be incorporated into operational flood forecasting tools, improving response and resilience to large flood events. Here, we present a comparison of several methods for characterizing flood inundation using a combination of synthetic aperture radar (SAR) remote sensing data and machine learning methods. We implement two applications with SAR GRD data, an amplitude thresholding technique applied, for the first time, to Sentinel-1A/B SAR data, and a machine learning technique, DeepLabv3+. We also apply DeepLabv3+ to a false color RGB characterization of dual polarization SAR data. Analyses at 10 m pixel spacing are performed for the major flood event associated with Hurricane Harvey and associated inundation in Houston, TX in August of 2017. We compare these results with high-resolution aerial optical images over this time period, acquired by the NOAA Remote Sensing Division. We compare the results with NDWI produced from Sentinel-2 images, also at 10 m pixel spacing, and statistical testing suggests that the amplitude thresholding technique is the most effective, although the machine learning analysis is successful at reproducing the inundation shape and extent. These results demonstrate the effectiveness of flood inundation mapping at unprecedented resolutions and its potential for use in operational emergency hazard response to large flood events. [ABSTRACT FROM AUTHOR]

We apply, for the first time, an equal-scattering-mechanism multibaseline optimization technique on quad-pol satellite images of RADARSAT-2 in order to increase the interferometric coherence. The optimized polarimetric channel results in the selection of new pixel candidates for multibaseline differential interferometric synthetic aperture radar applications, which, otherwise, are not recognized in any single-pol channel. In addition, we analyze the individual performance of this algorithm for rural and urban land covers along with the corresponding optimized scattering mechanisms. The optimized coherence improvement with respect to a single HH channel is shown to be correlated with the interferometric spatial and temporal baselines. Finally, we investigate the performance of this technique on the interferometric phase. The optimized interferograms increase the quality of the phase patterns with respect to those phases recovered in a single copolar channel, e.g., the residual orbital ramps of the RADARSAT-2 images. [ABSTRACT FROM PUBLISHER]

Abstract: We present new results for shallow aseismic creep on the Hayward fault in California using a new DInSAR technique. This method not only provides, for the first time, the ability to map the displacement field on both sides of the fault, it does so over a much shorter time period than earlier results. The results provide a good match in the near-field to both the regional continuous GPS velocities and data from an alinement network that measures long-term creep along the fault. The average slip rate for the northern segment of the Hayward fault is ∼4.4mm/yr between 2008 and 2011, slightly less than that estimated for longer time periods, suggesting that the slip rate may not be constant. If the slip rate along the fault is variable on the decadal or longer scale, current estimates of its earthquake potential and the associated hazard associated with the slip rate deficit may need to be revised from previous estimates. We demonstrate the potential impact of this method to better define the spatial and temporal complexity of aseismic slip and estimate the accumulated elastic strain along one of the most significant sources of seismic hazard in the San Francisco Bay area. [Copyright &y& Elsevier]

The Cushing Hub in Oklahoma, one of the largest oil storage facilities in the world, is federally designated as critical national infrastructure. In 2014, the formerly aseismic city of Cushing experienced a Mw 4.0 and 4.3 induced earthquake sequence due to wastewater injection. Since then, an M4+ earthquake sequence has occurred annually (October 2014, September 2015, November 2016). Thus far, damage to critical infrastructure has been minimal; however, a larger earthquake could pose significant risk to the Cushing Hub. In addition to inducing earthquakes, wastewater injection also threatens the Cushing Hub through gradual surface uplift. To characterize the impact of wastewater injection on critical infrastructure, we use Differential Interferometric Synthetic Aperture Radar (DInSAR), a satellite radar technique, to observe ground surface displacement in Cushing before and during the induced Mw 5.0 event. Here, we process interferograms of Single Look Complex (SLC) radar data from the European Space Agency (ESA) Sentinel-1A satellite. The preearthquake interferograms are used to create a time series of cumulative surface displacement, while the coseismic interferograms are used to invert for earthquake source characteristics. The time series of surface displacement reveals 4–5.5 cm of uplift across Cushing over 17 months. The coseismic interferogram inversion suggests that the 2016 Mw 5.0 earthquake is shallower than estimated from seismic inversions alone. This shallower source depth should be taken into account in future hazard assessments for regional infrastructure. In addition, monitoring of surface deformation near wastewater injection wells can be used to characterize the subsurface dynamics and implement measures to mitigate damage to critical installations. [ABSTRACT FROM AUTHOR]

This paper describes an approach to analyze ground deformation data collected by InSAR (Interferometric Synthetic Aperture Radar) imaging the volcano feeding system (VFS) beneath a caldera. The approach is applied to the Campi Flegrei caldera in southern Italy, a densely populated area at high risk for volcanic eruption. The method is a 4D tomographic inversion that considers a combination of 3D pressure sources and dislocations (strike-slip, dip-slip and tensile) acting simultaneously. This is in contrast to traditional methods that assume a priori geometries and type for the volcanic source. Another novelty is that we carry out a time-series analysis of multifrequency InSAR displacement data. The analysis of these multiplatform and multifrequency InSAR data from 2011 to 2022 reveals an inflating source at a depth of 3–4 km that is interpreted as a pressurized magmatic intrusion. The source broadens and migrates laterally over time, with a possible new magmatic pulse arriving in 2018–2020. The model also identifies a shallow region (at 400 m depth) that may be feeding fumaroles in the area. The analysis also reveals a zone of weakness (dip-slip) that could influence the path of rising magma. This method provides a more detailed dynamic 4 - dimensional image of the VFS than previously possible and could be used to improve hazard assessments in active volcanic areas. • InSAR and state-of-the-art inversion technique to improve volcano monitoring. • Ground deformation of Campi Flegrei caldera from 2011 to 2022. • 4D geodetic tomography of the volcano feeding system below the caldera. • Identification of magmatic fluids paths and fractured regions below the caldera. [ABSTRACT FROM AUTHOR]

Abstract: Rapidly accelerating ground subsidence in the south-western part of British Columbia, the third largest metropolitan area in Canada with over 2.3 million of inhabitants, is estimated using the Multidimensional Small Baseline Subset (MSBAS) advanced Differential Interferometric Synthetic Aperture Radar (DInSAR), an effective processing strategy for multi-mission, multi-temporal SAR data. The Synthetic Aperture Radar (SAR) data used in this study consists of seven independent data sets: one ascending and one descending ERS-1/2 and ENVISAT frames, together spanning July 1995–September 2010, and three RADARSAT-2 frames spanning February 2009–October 2012. During the July 1995–October 2012 period we observe fast ground subsidence with a maximum rate of about 2cm/year in the Greater Vancouver region that includes the Fraser River Delta and the cities of Burnaby, Richmond, Surrey, New Westminster and Vancouver. The rapidly accelerating subsidence is observed beneath the Vancouver International Airport, SkyTrain terminal as well as several agricultural and industrial locales. These time series suggest that the subsidence rate at the studied regions does not decrease with time, as suggested in previous studies, but remains steady or increases. These results also demonstrate the importance of acquiring and appropriately estimating longer time series, as previous studies on the same Greater Vancouver area may have misinterpreted the long term ground deformation rate and direction and underestimated the potential hazard. The long term impact of this subsidence on urban infrastructure can be significant and needs to be investigated further. [Copyright &y& Elsevier]

• New methodology constraining 3D volcanic sources using elementary sources aggregation. • It is effective in contexts where displacement is related to different sources. • No a-priori hypothesis about the causative sources is required. • The inversion process simultaneously inverts terrestrial and InSAR data. • It has been applied to the inversion of InSAR data for Mt. Etna during 2009-2013. Developments in Interferometric Synthetic Aperture Radar (InSAR) and GNSS (Global Navigation Satellite System) during the past decades have promoted significant advances in geosciences, providing high-resolution ground deformation data with dense spatio-temporal coverage. This large dataset can be exploited to produce accurate assessments of the primary processes occurring in geologically active areas. We present a new, original methodology to carry out a multi-source inversion of ground deformation data to better understand the subsurface causative processes. A nonlinear approach permits the determination of location, size and three-dimensional configuration, without any a priori assumption as to the number, nature or shape of the potential sources. The proposed method identifies a combination of pressure bodies and different types of dislocation sources (dip-slip, strike-slip and tensile) that represent magmatic sources and other processes such as earthquakes, landslides or groundwater-induced subsidence through the aggregation of elemental cells. This approach has the following features: (1) simultaneous inversion of the deformation components and/or line-of-sight (LOS) data; (2) simultaneous determination of diverse structures such as pressure bodies or dislocation sources, representing local and regional effects; (3) a fully 3D context; and (4) no initial hypothesis about the number, geometry or types of the causative sources is necessary. This methodology is applied to Mt. Etna (Southern Italy). We analyze the ground deformation field derived from a large InSAR dataset acquired during the January 2009 – June 2013 time period. The application of the inversion approach models several interesting buried structures as well as processes related to the volcano magmatic plumbing system, local subsidence within the Valle del Bove and seaward motion of eastern flank of the volcano. [ABSTRACT FROM AUTHOR]