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In geophysical inverse problems, the distribution of physical properties in an Earth model is inferred from a set of measured data. A necessary step is to select data that are best suited to the problem at hand. This step is performed ahead of solving the inverse problem, generally on the basis of expert knowledge. However, expert-opinion can introduce bias based on pre-conceptions. Here we apply a trans-dimensional algorithm to automatically weigh data on the basis of how consistent they are with the fundamental hypotheses made to solve the inverse problem. We demonstrate this approach by inverting arrival times for the location of a seismic source in an elastic half-space, assuming a point-source and uniform weights in concentric shells. The key advantage is that the data do no longer need to be selected by an expert, but they are assigned varying weights during the inversion procedure.

The original version of this article contained an error in Figure 1, in which the heading of panel (c) was mislabelled as ‘40 km’. The correct heading of panel (c) is ‘50 km’. The caption of Figure 1 also contained the same error. Both the panel heading and caption of Figure 1 have now been corrected in the PDF and HTML versions of the article.

A full understanding of the dynamics of mountain ranges such as the Alps requires the integration of available geological and geophysical knowledge into a lithospheric-scale 3-D geological model. As a first stage in the construction of this geo-model, we derive a new 3-D shear wave velocity model of the Alpine region, with a spatial resolution of a few tens of kilometres, making it possible to compare with geological maps. We use four years of continuous vertical-component seismic noise records to compute noise correlations between more than 950 permanent broad-band stations complemented by similar to 600 temporary stations from the AlpArray sea-land seismic network and the Cifalps and EASI linear arrays. A specific pre-processing is applied to records of ocean-bottom seismometers in the Liguro-Provencal basin to clean them from instrumental and oceanic noises. We first perform a 2-D transdimensional inversion of the traveltimes of Rayleigh waves to compute group-velocity maps from 4 to 150 s. The data noise level treated as an unknown parameter is determined with a Hierarchical Bayes method. A Fast Marching Eikonal solver is used to update ray path geometries during the inversion. We use next the group-velocity maps and their uncertainties to derive a 3-D probabilistic V-s model. The probability distributions of V-s at depth and the probability of presence of an interface are estimated at each location by exploring a set of 130 million synthetic four-layer 1-D V-s models. The obtained probabilistic model is refined using a linearized inversion. Throughout the inversion for V-s, we include the water column where necessary. Our V-s model highlights strong along-strike changes of the lithospheric structure, particularly in the subduction complex between the European and Adriatic plates. In the South-Western Alps, our model confirms the existence of a low-velocity structure at 50 - 80 km depth in the continuation of the European continental crust beneath the subduction

Background Precarious employment (PE), characterized by reduced worker rights, and employment and income insecurity, has complex public health implications including negative impacts on workers’ mental and physical health, occupational health and safety, wellbeing, and inequities in access to health and social protections. There is, however, a knowledge gap regarding effectiveness of interventions. We describe findings from a review of evaluated interventions with potential to address PE. Methods Our systematic review followed the 2020 PRISMA framework and covered PubMed, Scopus, Web of Science, and sources of grey literature. We included qualitative, quantitative, or mixed-methods studies evaluating initiatives to reduce workers’ PE published from 2000 to 2021 and focused on adult workers. Results The 23 eligible studies from across the world evaluated diverse strategies addressing PE including tax and trade reforms, industrial disputes legislation, business registration, and use of incentives to stimulate permanent contracts. Also included were union strategies to reach precarious workers, the provision of social benefits, and youth apprenticeships. Generally, while most initiatives had the potential to tackle certain PE aspects, they usually acted only on one or two PE dimensions. Additionally, the evaluation components were missing key details, thus, limiting the generalizability of findings, as did the heterogeneity of study designs, initiative purposes, economic and political context, and diverse populations targeted. Conclusions The increase in PE prevalence and its complex health implications requires sustainable upstream public health solutions. Multidisciplinary collaborations among public health and occupational health practitioners along with researchers, evaluation specialists, economists, and politicians could facilitate the implementation and evaluation of policies and standards regulating and monitoring PE and its health impacts. Key messages • Preca

The world of work is facing an ongoing pandemic and an economic downturn with severe effects worldwide. Workers trapped in precarious employment (PE), both formal and informal, are among those most affected by the COVID-19 pandemic. Here we call attention to at least 5 critical ways that the consequences of the crisis among workers in PE will be felt globally: (a) PE will increase, (b) workers in PE will become more precarious, (c) workers in PE will face unemployment without being officially laid off, (d) workers in PE will be exposed to serious stressors and dramatic life changes that may lead to a rise in diseases of despair, and (e) PE might be a factor in deterring the control of or in generating new COVID-19 outbreaks. We conclude that what we really need is a new social contract, where the work of all workers is recognized and protected with adequate job contracts, employment security, and social protection in a new economy, both during and after the COVID-19 crisis.

We present PRISM3D, a 3-D reference seismic model of P- and S-wave velocities for Iberia and adjacent areas. PRISM3D results from the combination of the most up-to-date earth models available for the region. It extends horizontally from 15°W to 5°E in longitude, 34°N to 46°N in latitude and vertically from 3.5 km above to 200 km below sea level, and is modelled on a regular grid with 10 and 0.5 km of grid node spacing in the horizontal and vertical directions, respectively. It was designed using models inferred from local and teleseismic body-wave tomography, earthquake and ambient noise surface wave tomography, receiver function analysis and active source experiments. It includes two interfaces, namely the topography/bathymetry and the Mohorovičić (Moho) discontinuity. The Moho was modelled from previously published receiver function analysis and deep seismic sounding results. To that end we used a probabilistic surface reconstruction algorithm that allowed to extract the mean of the Moho depth surface along with its associated standard deviation, which provides a depth uncertainty estimate. The Moho depth model is in good agreement with previously published models, although it presents slightly sharper gardients in orogenic areas such as the Pyrenees or the Betic-Rif system. Crustal and mantle P- and S-wave wave speed grids were built separately on each side of the Moho depth surface by weighted average of existing models, thus allowing to realistically render the speed gradients across that interface. The associated weighted standard deviation was also calculated, which provides an uncertainty estimation on the average wave speed values at any point of the grid. At shallow depths (<10 km), low P and S wave speeds and high VP/VS are observed in offshore basins, while the Iberian Massif, which covers a large part of western Iberia, appears characterized by a rather flat Moho, higher than average VP and VS and low VP/VS. Conversely, the Betic-Rif system seems to be

When different geophysical observables are sensitive to the same volume, it is possible to invert them simultaneously to jointly constrain different physical properties. The question addressed in this study is to determine which structures (e.g., interfaces) are common to different properties and which ones are separated. We present an algorithm for resolving the level of spatial coupling between physical properties and to enable both common and separate structures in the same model. The new approach, called structure decoupling (SD) algorithm, is based on a Bayesian trans-dimensional adaptive parameterization, where models can display the full spectra of spatial coupling between physical properties, from fully coupled models, that is, where identical model geometries are imposed across all inverted properties, to completely decoupled models, where an independent parameterization is used for each property. We apply the algorithm to three 1-D geophysical inverse problems, using both synthetic and field data. For the synthetic cases, we compare the SD algorithm to standard Markov chain Monte Carlo and reversible-jump Markov chain Monte Carlo approaches that use either fully coupled or fully decoupled parameterizations. In case of coupled structures, the SD algorithm does not behave differently from methods that assume common interfaces. In case of decoupled structures, the SD approach is demonstrated to correctly retrieve the portion of profiles where the physical properties do not share the same structure. The application of the new algorithm to field data demonstrates its ability to decouple structures where a common stratification is not supported by the data.

The dynamics of continental subduction is largely controlled by the rheological properties of rocks involved along the subduction channel. Serpentinites have low viscosity at geological strain rates. However, compelling geophysical evidence of a serpentinite channel during continental subduction is still lacking. Here we show that anomalously low shear-wave seismic velocities are found beneath the Western Alps, along the plate interface between the European slab and the overlying Adriatic mantle. We propose that these seismic velocities indicate the stacked remnants of a weak fossilised serpentinite channel, which includes both slivers of abyssal serpentinite formed at the ocean floor and mantle-wedge serpentinite formed by fluid release from the subducting slab. Our results suggest that this serpentinized plate interface may have favoured the subduction of continental crust into the upper mantle and the formation/exhumation of ultra-high pressure metamorphic rocks, providing new constraints to develop the conceptual and quantitative understanding of continental subduction dynamics.

BACKGROUND: Keeping older workers in employment is critical for societies facing the challenge of an ageing population. This study examined the association between types of health conditions and differentials in the probability of employment by level of education among men and women between 60-69 years of age in Canada, Denmark, Sweden and England. METHODS: Data were drawn from the Canadian Community Health Survey, Survey of Health, Ageing and Retirement in Europe and English Longitudinal Study of Ageing. We combined country data, applied logistic regression, adjusted for educational level, and stratified the analysis by sex to calculate the odds ratio (OR) of employment (>15 hours work per week) for persons with physical health conditions, mental health conditions (depression) and physical-mental health comorbidity. RESULTS: The odds of employment among men and women with physical-mental health comorbidity were lower compared to those with no/other conditions (men: OR 0.32, 95% CI: 0.25-0.42, women: OR 0.38 95% CI: 0.30-0.48). Women with low education had lower odds of employment compared to their counterparts with high education (OR 0.66, 95% CI: 0.57-0.76). The odds of employment at older ages was lower in Canada, Denmark and England compared with Sweden (e.g. English men: OR 0.48 95% CI 0.40-0.58; English women OR 0.33 95% CI 0.27-0.41). CONCLUSIONS: The odds of employment beyond age 60 is lower for groups with low education, particularly women, and those with physical-mental health co-morbidities. As such, policies to extend working lives should not be 'one size fits all' but instead consider subgroups, in particular, these groups that we have shown to be most vulnerable on the labour market.

The assembly of East Asia was closely linked to the closure of the Tethyan oceans. In south-east China, the closure of the Paleo-Tethys ocean led to a continental collision between the South China and North China blocks (SCB and NCB), forming the world renowned (ultra-) high pressure (UHP) metamorphic belt of the Dabie-Sulu Orogen. The region was subsequently reworked by postorogenic extensional processes. These tectonic processes likely have left lithospheric scars identifiable by seismic imaging techniques. Here we characterize seismic structures across the orogen and analyze processes related to the closure of the Paleo-Tethys. Using cutting-edge tomographic approaches and ambient noise dispersion data, we developed a fine-scale crustal shear-wave velocity model beneath key crustal domains in the region. Distinct crustal scale velocity domains are identified, corresponding to the normal Precambrian crust, slow-velocity suture zones and fault systems, and fast-velocity orogens, suggesting a deep root of the corresponding surface geological features. By combining recent models of active-source, gravity and magnetotellurics, characteristic lithospheric deformation patterns such as crustal thrust systems and lithospheric wedges can be inferred, which are attributed to a northward subduction of the SCB lithosphere and the eventual continental collision after the closure of the Paleo-Tethys Ocean.

BACKGROUND: In most developed countries, governments are implementing policies encouraging older persons to work past 65 years to reduce the burden on societies related to disability benefits and pension payments. Despite this push to extend working lives, we know little about who already works past this age and any inequalities that may exist. Our study investigates the employment rates of those aged 65-75 years of age by educational level, health status and sex in Canada (CAN), Denmark (DK), Sweden (SE) and the United Kingdom (UK). Secondly, we aim to relate findings on employment rates to prevailing policies in the different countries, to increase the understanding on how to further extend working lives. METHODS: We used nationally representative cross-sectional survey data from the 2012-2013 Canadian Community Health Survey, 2013/14 Survey of Health, Ageing and Retirement in Europe for Denmark and Sweden and the 2013 English Longitudinal Study of Ageing to examine employment rates for those aged 65-75 years by sex, educational level and health status (having limiting longstanding illness (LLI) or not). RESULTS: Employment rates decline by age, but we see a linear decline in CAN and the UK compared to an initial decline then a plateau of employment rates from 66 to 68 years in DK and SE. Employment rates among persons aged 65-75 years were lower in the UK than in CAN, DK and SE. Among women, employment rates were highest in SE. Women with low education and a LLI had considerably lower employment rates than men with low education and a LLI (employment rates for men ranged from 27% to 12% compared with employment rates for women which ranged from 12% to 0%). CONCLUSIONS: Our results suggest that educational level, sex and health all play a role in extending working lives. The variation in employment rates between the four countries implies that policies do matter, but that social differentials show that policies cannot be 'one size fits all'. Policy-makers must con

Simple models involving the gradual outboard accretion of material along curvilinear subduction zones are often inconsistent with field-based evidence. A recent study using 3-D geodynamic modelling has shown that the entrainment of an exotic continental fragment within a simple subduction system can result in a complex phase of growth. Although kinematic models based on structural mapping and high-resolution gravity and magnetic maps indicate that the pre-Carboniferous Tasmanides in southeastern Australia may have been subjected to this process, to date there has been little corroboration from crustal scale geophysical imaging. Here, we apply Bayesian transdimensional tomography to ambient noise data recorded by the WOMBAT transportable seismic array to constrain a detailed (20 km resolution in some areas) 3-D shear velocity model of the crust beneath southeast Australia. We find that many of the velocity variations that emerge from our inversion support the recently developed geodynamic and kinematic models. In particular, the full thickness of the exotic continental block, responsible for orocline formation and the tectonic escape of the back arc region, is imaged here for the first time. Our seismic results provide the first direct evidence that exotic continental fragments may profoundly affect the development of an accretionary orogen.