Is the Sevier Desert Reflection of West-Central Utah a Normal Fault?: Comment and Reply

Forum discussion on an article originally by Anders et al. Allmendinger and Royse critique Anders et al.'s argument, to which Anders et al. responds. Critique abstract: The continuing discussion of the Sevier Desert region, almost 20 years after MacDonald’s (1976) classic paper, provides a measure of the significance of the region as well as the non-uniqueness of seismic reflection data interpretation. The article by Anders and Christie-Blick (1994) and the nearly simultaneous publication of similar ideas by Hamilton (1994) raise important questions. The interpretation of a Sevier Desert detachment has always been a hypothesis to be tested rather than a fact. In our opinion, however, Anders and Christie-Blick and Hamilton have ignored a variety of basic geologic data requiring the presence of a major low-angle normal fault on the east side of the Sevier Desert basin. Response abstract: We concur with Allmendinger and Royse’s assessment of the detachment interpretation for the Sevier Desert reflection as a ‘‘hypothesis to be tested.’’ We reported on an attempt to do just that: to look for evidence for fault-related deformation in samples from two boreholes that intersect this feature. The absence of evidence for cataclasis in the inferred hanging-wall block or ductile deformation in the footwall naturally raises some interesting issues for the tectonic interpretation of the Sevier Desert. In drawing attention to these issues, we have not ‘‘ignored’’ any basic geologic data, nor are we aware of any data that ‘‘require’’ the presence of a major low-angle normal fault

How strong are salt marshes? Geotechnical properties of coastal wetland soils

Funder: British Geological Survey; Id: http://dx.doi.org/10.13039/501100002760This paper compares two marshes of contrasting sedimentology at Tillingham marsh, eastern England, and Warton marsh, North West England. Soil shear strength and compressibility are determined by applying geotechnical methods to determine marsh resistance to shear- and vertical effective- stresses. This research was able to isolate the influence of roots on substrate shear strength in a three-dimensional sample. In response to vertical effective stress, both the expected displacement magnitude and the vertical recovery potential of a marsh substrate are affected by past stress conditions on the marsh, particularly those resulting from desiccation. The substrate response to vertical effective stress also influences substrate shear strength through the effect of consolidation on the void ratio (or bulk density)

Effect of vegetation cover and sediment type on 3D subsurface structure and shear strength in saltmarshes

Funder: Queen Mary; Id: http://dx.doi.org/10.13039/100009148Abstract: The vulnerability of saltmarshes to lateral erosion at their margin depends on the local biogeomorphological properties of the substrate. In particular, the 3D architecture of pore and root systems is expected to influence shear strength, with repercussions for the wider‐scale stability of saltmarshes. We apply X‐ray computed microtomography (μCT) to visualize and quantify subsurface structures in two UK saltmarshes at Tillingham Farm, Essex (silt/clay rich substrate) and Warton Sands (sand‐rich substrate), with four types of ground cover: bare ground, Spartina spp, Salicornia spp and Puccinellia spp. We extracted μCT structural parameters that characterize pore and root morphologies at each station, and compared them with field measurements of shear strength using a principal component analysis and correlation tests. The 3D volumes show that species‐dependent variations in root structures, plant colonization events and bioturbation activity control the morphology of macropores, while sediment cohesivity determines the structural stability and persistence of these pore structures over time, even after the vegetation has died. Areas of high porosity and high mean pore thickness were correlated to lower values of shear strength, especially at Tillingham Farm, where well‐connected vertical systems of macropores were associated with current or previous colonization by Spartina spp. However, while well‐connected systems of macropores may lower the local deformation threshold of the sediment, they also encourage drainage, promote vegetation growth and reduce the marsh vulnerability to hydrodynamic forces. The highest values of shear strength at both sites were found under Puccinellia spp, and were associated with a high density of mesh‐like root structures that bind the sediment and resist deformation. Future studies of marsh stability should ideally consider time series of vegetation cover, especially in silt/clay‐dominated saltmarshes, in order to consider the potential effect of preserved buried networks of macropores on water circulation, marsh functioning and cliff‐face erosion

Clinical outcomes after implantation of a sutureless aortic bioprosthesis with concomitant mitral valve surgery: the SURE-AVR registry

Background: Early treatment of aortic valve stenosis is recommended in eligible symptomatic patients with severe aortic valve stenosis who would otherwise have a poor prognosis. The sutureless aortic valve bioprosthesis offers an alternative to standard aortic valve replacement with a sutured valve, but limited data are available in patients who have undergone multiple valve procedures involving the new, sutureless technology. We sought to investigate outcomes in high operative risk patients with previous or concomitant valve surgery who were implanted with a sutureless valve. Methods: SURE-AVR is an ongoing, prospective, multinational registry of patients undergoing aortic valve replacement. In-hospital and post-discharge outcomes up to 5 years were collected. Results: The study population comprised 78 patients (mean \ub1 SD: age 73.6 \ub1 7.6 years, logistic EuroSCORE 18.0 \ub1 17.5) enrolled at 13 sites who presented for concomitant or previous mitral valve repair (n\ua0= 45) or replacement (n\ua0= 33), with or without additional concomitant procedures, and were implanted with a sutureless valve. Mean \ub1 SD overall aortic cross-clamp time was 109 \ub1 41 min and cardiopulmonary bypass time was 152 \ub1 49 min. Mean \ub1 SD aortic pressure gradients decreased from 37.6 \ub1 17.7 mmHg preoperatively to 13.0 \ub1 5.7 mmHg at hospital discharge, and peak aortic pressure gradient from 61.5 \ub1 28.7 to 23.4 \ub1 10.6 mmHg. Early events included 1 death, 1 transient ischaemic attack, and 1 bleed (all 1.3%); a permanent pacemaker implantation was required in 6 patients (7.7%), and 2 reoperations (not valve related) (2.6%) took place. Over a median follow-up of 55.5 months (Q1 13.4, Q3 68.6), 12 patients died (6 cardiovascular and 6 non-cardiovascular, both 2.1% per patient-year). Five-year survival was 81.3%. Late paravalvular leak occurred in 2 patients (0.7% per patient-year) and permanent pacemaker implantation was required in 3 patients (0.1% per patient-year). There was no apparent rise in mean or peak aortic pressure gradient over the study. Conclusions: These results suggest that the sutureless implant is a technically feasible procedure during mitral surgery and is associated with good clinical outcomes

Anomalous buried hollows in London: development of a hazard susceptibility map

Engineering works carried out in central London over many decades have revealed a number of buried hollows that exhibit curious characteristics. Some extend deep into the bedrock geology and are in-filled with disturbed superficial deposits and reworked bedrock. Others are contained within the superficial deposits. They can be up to 500 m wide and more than 60 m in depth. As the infill material often has different behavioural characteristics from the surrounding deposits failure to identify them during an initial site investigation can prove costly. This paper considers their common characteristics and describes the method used to develop a buried hollow hazard susceptibility map. This map provides planners with a broader awareness of the potential location of difficult ground conditions associated with them, thereby reducing the potential for unforeseen ground conditions through effective site investigation design. The paper continues with a discussion of some of the likely processes associated with their formation, which are attributed to cryogenic processes, and concludes with potential future research directions

A Multi-Site Analysis of the Prevalence of Food Insecurity in the United States, before and during the COVID-19 Pandemic

Background: The coronavirus disease 2019 (COVID-19) pandemic profoundly affected food systems including food security. Understanding how the COVID-19 pandemic impacted food security is important to provide support and identify long-term impacts and needs. Objective: The National Food Access and COVID research Team (NFACT) was formed to assess food security over different US study sites throughout the pandemic, using common instruments and measurements. This study presents results from 18 study sites across 15 states and nationally over the first year of the COVID-19 pandemic. Methods: A validated survey instrument was developed and implemented in whole or part through an online survey of adults across the sites throughout the first year of the pandemic, representing 22 separate surveys. Sampling methods for each study site were convenience, representative, or high-risk targeted. Food security was measured using the USDA 6-item module. Food security prevalence was analyzed using ANOVA by sampling method to assess statistically significant differences. Results: Respondents (n = 27,168) indicate higher prevalence of food insecurity (low or very low food security) since the COVID-19 pandemic, compared with before the pandemic. In nearly all study sites, there is a higher prevalence of food insecurity among Black, Indigenous, and People of Color (BIPOC), households with children, and those with job disruptions. The findings demonstrate lingering food insecurity, with high prevalence over time in sites with repeat cross-sectional surveys. There are no statistically significant differences between convenience and representative surveys, but a statistically higher prevalence of food insecurity among high-risk compared with convenience surveys. Conclusions: This comprehensive study demonstrates a higher prevalence of food insecurity in the first year of the COVID-19 pandemic. These impacts were prevalent for certain demographic groups, and most pronounced for surveys targeting high-risk populations. Results especially document the continued high levels of food insecurity, as well as the variability in estimates due to the survey implementation method

Making geology relevant for infrastructure and planning

The urban population is projected to rise to 66% in 2050 to 7.6 billion. This has had, and will have, a profound effect on the geological and geomorphological character of the Earth’s shallow geosphere. It is important to know the character and geometries of the geological deposits so that infrastructure is planned sensibly and sustainably, and urban areas can be reused responsibly to ensure that they help facilitate economic and social development. This brings major challenges for our cities, where there is increased pressure on resources, space and services. The geosciences have an important part to play in securing sustainable global cities - they can support urban innovation and city performance, reduce our environmental footprint and ensure greater resilience to natural hazards such as flooding and ground instability. For more than 30 years the British Geological Survey has advanced the geoscientific understanding and 3D characterisation of urban environments, producing multi-themed spatial datasets for geohazards and ground investigation used across the environmental, planning and insurance sectors. The BGS have collaborated with the University of Cambridge to better integrate geological data with landuse and infrastructure to look at the long-term impact on these types of activities at surface and subsurface. A 3D GeoLanduse layer was produced from the geological framework model of London. This vector-based grid means that many soil and rock properties (e.g. foundation conditions, groundwater levels, volume change potential), can be represented alongside landuse statistics and infrastructure type and correlated in the XYZ domain. Focus has been at geothermal potential of the ground surrounding residential basements and the broader correlation between geology, energy consumption and landuse at city scale using principle component analysis and cluster recognition