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The increased need for water resources in urban sprawls and intense droughts has forced more aggressive groundwater extraction resulting in numerous urban areas undergoing land subsidence. In most cases, only some large metropolitan areas have been well-characterized for subsidence. However, there is no existing country-wide assessment of urban areas, population, and households exposed to this process. This research showcases a methodology to systematically evaluate urban localities with land subsidence higher than - 2.8 cm/year throughout Mexico. We used Interferometric Synthetic Aperture Radar (InSAR) tools with a dataset of 4611 scenes from European Space Agency's Sentinel-1 A/B SAR sensors acquired from descending orbits from September 2018 through October 2019. This dataset was processed at a supercomputer using InSAR Scientific Computing Environment and the Miami InSAR Time Series software in Python software. The quality and calibration of the resulting velocity maps are assessed through a large-scale comparison with observations from 100 continuous GPS sites throughout Mexico. Our results show that an urban area of 3797 km2, 6.9 million households, and 17% of the total population in Mexico is exposed to subsidence velocities of faster than - 2.8 cm/year, in more than 853 urban localities within 29 land subsidence regions. We also confirm previous global potential estimations of subsidence occurrence in low relief areas over unconsolidated deposits and where groundwater aquifers are under stress. The presented research demonstrates the capabilities for surveying urban areas exposed to land subsidence at a country-scale level by combining Sentinel-1 velocities with spatial national census data. Supplementary Information: The online version contains supplementary material available at 10.1007/s11069-023-06259-5.

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The Delaware Basin in west Texas and southeast New Mexico is now the largest global oil producing basin, averaging ∼400,000 m3 (∼2,500,000 barrels) per day in 2022. The shale-dominated strata targeted for production can co-produce 4-5 times more water than oil, necessitating disposal by injection of ∼1,400,000 m3 (∼8,700,000 barrels) of water per day in 2022. Through a comprehensive assimilation of regional Sentinel-1 satellite radar data and analysis of production and injection, we show how petroleum operations have caused the development of complex and accelerating patterns of surface deformation from 2015 through 2021. We observe uplift from reservoir swelling, subsidence from reservoir contraction, and the development of linear features that are indicative of faulting. Subsidence is predominantly caused by production, and an important finding of this study is that the magnitude of subsidence is linearly proportional to total production. Uplift is caused by pressurization from wastewater injection of shallow permeable strata. The patterns of uplift are complex and extend laterally well-beyond areas where injection was performed. Linear surface deformation features are observed throughout the Delaware Basin, and they are lengthening and densifying as uplift and subsidence accelerate. Many of the lineations can be linked to known strata-bounded faults and shallow seismicity in the southern Delaware Basin where they serve as permeable and anisotropic conduits for pore pressure migration. In the Northern Delaware Basin, co-seismic rupture is hosted along basement-rooted faults that may link to the linear surface features. Understanding these dynamic changes in Delaware Basin is a pressing concern for management of subsurface reservoirs and safeguarding the surface environment. Concerns include ongoing induced seismicity, hazard of drilling through over-pressured strata, maintenance of integrity for newer wellbores, mitigation of flows of brine and petroleum fluids at the surface of old wellbores, and management of the pore space resource for wastewater injection.

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Limited attention is typically paid to the cause-effect relationship between land subsidence due to aquifers overexploitation in expanding metropolises and urban growth models and patterns. This paper implements an integrated urban and satellite Interferometric Synthetic Aperture Radar (InSAR) approach to investigate subsidence, multi-decadal urban growth and peopling trends in the Metropolitan Area of Morelia (ZMM) in the Mexican state of Michoacán. Stacking of JRC's Global Human Settlement Layer, DLR's World Settlement Footprint and INEGI's National Geostatistical Framework datasets reveals a predominant edge-expansion growth model, with urban densification in 1975-2020 and some sprawling in 1990-2000. Population of the ZMM doubled in the last 30 years, reaching over 1 million inhabitants. The ENVISAT and Sentinel-1 InSAR analysis confirms that subsidence is structurally-controlled by the main normal faults within the Cuitzeo half-graben. Differential sinking and ground discontinuities are aligned with buried tectonic faults and contrasting compressible sediment thickness. Non-linearly deforming subsidence bowls develop at extraction wells in both old and newly urbanized sectors of the ZMM. Maximum vertical displacement velocities increased from -2.5 cm/year in 2003-2010 to -9.0 cm/year in 2014-2021, with subsidence migrating towards recently urbanized zones. More than 250 new groundwater wells were added to the public registry since 2000, many of which within new urban sectors. Time-lapse InSAR reveals a 4 km2 rapidly subsiding bowl that formed at the largest social housing neighbourhood of Villas del Pedregal, as building lots were progressively completed and sold, and new wells registered. With angular distortions due to the differential subsidence reaching 0.12% in 2014-2021, new buildings and roads are exposed to fracturing and surface faulting risk of comparable level as the city historic building blocks located along the main faults. By providing useful insights into the relationship between urban growth and land subsidence in the ZMM, the approach proves valuable for application to other metropolises worldwide.

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Tailings dams are usually ponds bounded by valleys or surrounding topography to store mining or other chemical industrial waste. On 25 January 2019, the collapse of a tailings dam at the Córrego do Feijao iron ore mine (Brumadinho, Minas Gerais, Brazil) released about 12 million m3 of tailings, killing over 240 people and posing a considerable and ongoing environmental threat. The stability of tailings dam monitoring is very important and in the present paper, a new InSAR (Synthetic Aperture Radar Interferometry) time series approach is proposed to derive ground displacement maps for use in dam safety monitoring. Compared with the other solutions, the unique feature of the proposed method is that: 1) the new Measurement Pixel (MP) selection criteria has the potential to include relatively more accurate MP pixels and build a more robust network, 2) the multi-level grading system makes it possible to add the MP pixels into the main network step-by-step with external control, and 3) the computing efficiency can be improved by strategically reducing the iteration times. The proposed approach was tested on both simulated and real data. Results show that the Simulated Annealing (SA) method normally has a more accurate estimation as compared to the Quasi-Newton (QN) method, despite its longer processing time. Detailed analysis of the displacement maps was conducted to determine the subsidence processes that result from dam construction.

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This study aimed to validate the interferometric synthetic aperture radar (InSAR) method by using relative and absolute Global Navigation Satellite System (GNSS) techniques. In this context, two land subsidence areas, one high (Mexico City) and one medium (Aguascalientes), were monitored between 2014 and 2018 by using Sentinel 1A satellite data. The monitoring was carried out with the Small Baseline Subset (SBAS) technique using 46 images for Mexico City and 18 images for Aguascalientes. Concordantly, the GNSS Continuously Operating Reference Station (CORS) data in the regions were analyzed with relative and Precise Point Positioning (PPP) GNSS analysis techniques. The time series obtained from three different analyses were compared and the results were evaluated in light of statistical criteria. According to the results, it is determined that the InSAR-SBAS technique can vary up to ± 20 mm from the displacement values obtained from GNSS due to various noise sources. Such deviations were limited to a few samples, and in general the differentiations were reasonable in the range of 7-8 mm. The difference between the deformation velocity estimation results obtained from the three different methods varied between 3 and 10 mm/year. In this context, these findings suggest that the InSAR-SBAS technique is an effective method for monitoring land deformation with the accuracy of sub-centimeter decided. In addition, PPP which has become an increasingly popular technique showed fast and reliable results in the range of 5-10 mm for InSAR verification. Moreover, with this study, most current results for Mexico City, which is the world's fastest subsiding metropole, were achieved. In the central region of the city, the detected 300 mm/year of subsidence rate was updated as 370 mm/year. In addition, Aguascalientes was monitored by using the Sentinel 1A satellite mission for the first time in this study. The 60 mm/year subsidence rate obtained for Aguascalientes in previous studies was updated and it was estimated that there are zones where this rate reaches up to - 115 mm/year levels. In this regard, it was concluded that the deformation rate has increased for both regions since the previous monitoring studies.

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Floods in cities are increasingly common as a consequence of multifactor watershed dynamics, including geomorphology, land-use changes and land subsidence. However, urban managers have focused on infrastructure to address floods by reducing blocked sewage infrastructure, without significant success. Using Mexico City as a case study, we generated a spatial flood risk model with geomorphology and anthropogenic variables. The results helped contrast the implications of different public policies in land use and waste disposal, and correlating them with flood hazards. Waste disposal was only related to small floods. 58% of the city has a high risk of experiencing small floods, and 24% of the city has a risk for large floods. Half of the population with the lowest income is located in the high-risk areas for large floods. These models are easy to build, generate fast results and are able to help to flood policies, by understanding flood interactions in urban areas within the watershed.

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BACKGROUND: Cervical spondylotic myelopathy is caused by cervical stenosis. Several techniques have been described for the treatment of multilevel disease, such as the anterior corpectomy with titanium mesh cage and anterior cervical plate placement, which has the advantage of performing a wider decompression and using the same bone as graft. However, it has caused controversy since the collapse of the mesh cage continues being a major limitation of this procedure. MATERIAL AND METHOD: A prospective 4-year follow-up study was conducted in 7 patients diagnosed with cervical stenosis, who were treated surgically by one level corpectomy with titanium mesh cage and anterior cervical plate placement, evaluating them by radiographs and clinical scales. RESULTS: 7 patients, 5 women and 2 males were studied. The most common level was C5 corpectomy (n=4). The Neck Disability Index (NDI) preoperative average was 30.01±24.32 and 4-year postoperative 16.90±32.05, with p=0.801. The preoperative and 4-year postoperative Nürick was 3.28± 48 and 3.14±1.21 respectively, with p=0.766. Preoperative lordosis was 14.42±8.03 and 4-year postoperative 17±11.67 degrees, with p=0.660. The immediate postoperative and 4-year postoperative subsidence was 2.69±2.8 and 6.11±1.61 millimeters respectively, with p=0.0001. CONCLUSIONS: Despite the small sample, the subsidence of the mesh cage is common in this procedure. No statistically significant changes were observed in the lordosis or Nürick scale and NDI.

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ABSTRACT Objective: To evaluate the loss of correction after treatment of spine deformities with the technique of isolated posterior vertebrectomy. Methods: Twenty-one patients were followed-up for three years after surgery with panoramic X-rays, CT scans, SF-36 and Oswestry questionnaires. We evaluated the loss of correction, CAGE subsidence and the evolution of the pelvis-T1 angle during follow-up. The correlation among the radiographic changes and functional and quality of life scores was also assessed. Results: All patients had some degree of loss of correction and subsidence of CAGE, especially in the first year of follow-up. Such losses exerted negative impact on the function, pain and self-image of the patients. Factors such as the stiffness of the fusion mass and size of implant used appear to have contributed to the occurrence of subsidence, regardless of age and bone mineral density. Conclusions: The use of spacers with larger cross-sectional diameter and more rigid rods can reduce the overloading on the anterior column of Denis, reducing the subsidence and loss of correction. Additional stabilization strategies such as the use of orthoses postoperatively can also be useful, and should be evaluated in subsequent studies.

RESUMO Objetivo: Avaliar a perda de correção após o tratamento de deformidades da coluna vertebral pela técnica de vertebrectomia posterior isolada. Métodos: Vinte e um pacientes foram acompanhados durante três anos após o tratamento cirúrgico com radiografias panorâmicas, tomografias computadorizadas e através dos questionários SF-36 e Oswestry. Foram avaliadas perda de correção, subsidência do CAGE e evolução do ângulo pelve-T1 durante o acompanhamento. Também foi avaliada a correlação entre as alterações radiológicas e os índices funcionais e de qualidade de vida. Resultados: Todos os pacientes apresentaram algum grau de perda de correção e subsidência do espaçador intersomático, especialmente no primeiro ano de acompanhamento. Tais perdas exerceram impacto negativo sobre função, dor e autoimagem dos pacientes. Fatores como a rigidez da massa de artrodese e as dimensões do implante utilizado parecem ter contribuído com a ocorrência de subsidência, a despeito de faixa etária e densidade mineral óssea. Conclusões: O uso de espaçadores com maior diâmetro seccional e hastes mais rígidas podem reduzir a sobrecarga da coluna anterior de Denis, diminuindo a ocorrência de subsidência e perda de correção. Estratégias de estabilização adicionais, como o uso de órteses no pós-operatório também podem ser úteis, e devem ser avaliadas em estudos subsequentes.

RESUMEN Objetivo: Evaluar la pérdida de corrección después del tratamiento de las deformidades de la columna vertebral mediante la técnica de vertebrectomía posterior aislada. Métodos: Veintiún pacientes fueron seguidos durante tres años después de la cirugía mediante radiografías panorámicas, tomografías computarizadas y con el uso de los cuestionarios SF-36 y Oswestry. Se evaluó la pérdida de la corrección, la subsidencia del CAGE y la evolución del ángulo pelvis-T1 durante el seguimiento. También se evaluó la corrección entre las alteraciones radiográficas y los índices funcionales y de calidad de vida. Resultados: Todos los pacientes presentaron algún grado de pérdida de corrección y subsidencia del espaciador intersomático, especialmente en el primer año de seguimiento. Estas pérdidas ejercen impacto negativo sobre la función, el dolor y la autoimagen de los pacientes. Factores como la rigidez de la masa de artrodesis y el tamaño del implante usado parecen haber contribuido a la aparición de subsidencia, independientemente de la edad y la densidad mineral ósea. Conclusiones: El uso de espaciadores con diámetro de la sección transversal mayor y barras más rígidas pueden reducir la sobrecarga de la columna anterior de Denis, reduciendo la ocurrencia de subsidencia y pérdida de la corrección. Las estrategias de estabilización adicionales, tales como el uso de ortesis en el postoperatorio también pueden ser útiles, y deben ser evaluadas en estudios posteriores.

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BACKGROUND: Ulf Fernström implanted stainless steel ball bearings following discectomy, or for painful disc disease, and termed this procedure disc arthroplasty. Today, spherical interbody spacers are clinically available, but there is a paucity of associated biomechanical testing. The primary objective of the current study was to evaluate the biomechanics of a spherical interbody implant. It was hypothesized that implantation of a spherical interbody implant, with combined subsidence into the vertebral bodies, would result in similar ranges of motion (RoM) and facet contact forces (FCFs) when compared with an intact condition. A secondary objective of this study was to determine the effect of using a polyetheretherketone (PEEK) versus a cobalt chrome (CoCr) implant on vertebral body strains. We hypothesized that the material selection would have a negligible effect on vertebral body strains since both materials have elastic moduli substantially greater than the annulus. METHODS: A finite element model of L3-L4 was created and validated by use of ROM, disc pressure, and bony strain from previously published data. Virtual implantation of a spherical interbody device was performed with 0, 2, and 4 mm of subsidence. The model was exercised in compression, flexion, extension, axial rotation, and lateral bending. The ROM, vertebral body effective (von Mises) strain, and FCFs were reported. RESULTS: Implantation of a PEEK implant resulted in slightly lower strain maxima when compared with a CoCr implant. For both materials, the peak strain experienced by the underlying bone was reduced with increasing subsidence. All levels of subsidence resulted in ROM and FCFs similar to the intact model. CONCLUSIONS: The results suggest that a simple spherical implant design is able to maintain segmental ROM and provide minimal differences in FCFs. Large areas of von Mises strain maxima were generated in the bone adjacent to the implant regardless of whether the implant was PEEK or CoCr.