More than 10 years of geodetic measurements demonstrate an uplift rate of 1–3 mm/yr of the high topography region of the Western Alps. By contrast, no significant horizontal motion has been detected. ...Two uplift mechanisms have been proposed: (1) the isostatic response to denudation responsible for only a fraction of the observed uplift and (2) the rebound induced by the Wurmian ice cap melting which predicts a broader uplifting region than the one evidenced by geodetic observations. Using a numerical model to fit the geodetic data, we show that a crustal viscosity contrast between the foreland and the central part of the Alps, the latter being weaker with a viscosity of 1021 Pa s, is needed. The vertical rates are enhanced if the strong uppermost mantle beneath the Moho is interrupted across the Alps, therefore allowing a weak vertical rheological anomaly over the entire lithosphere.
Key Points
Explanation for the geodetic uplift of the Alps
Revisit the relation between deglaciation and uplift
Pointing out the key role of rheology on strain
In this paper we present the potential of a new compact superconducting gravimeter (GWR iGrav) designed for groundwater monitoring. At first, 3 yr of continuous gravity data are evaluated and the ...performance of the instrument is investigated. With repeated absolute gravity measurements using a Micro-g Lacoste FG5, the calibration factor (−894.8 nm s−2 V−1) and the long-term drift of this instrument (45 nm s−2 yr−1) are estimated for the first time with a high precision and found to be respectively constant and linear for this particular iGrav. The low noise level performance is found similar to those of previous superconducting gravimeters and leads to gravity residuals coherent with local hydrology. The iGrav is located in a fully instrumented hydrogeophysical observatory on the Durzon karstic basin (Larzac plateau, south of France). Rain gauges and a flux tower (evapo-transpiration measurements) are used to evaluate the groundwater mass balance at the local scale. Water mass balance demonstrates that the karst is only capacitive: all the rainwater is temporarily stored in the matrix and fast transfers to the spring through fractures are insignificant in this area. Moreover, the upper part of the karst around the observatory appears to be representative of slow transfer of the whole catchment. Indeed, slow transfer estimated on the site fully supports the low-flow discharge at the only spring which represents all groundwater outflows from the catchment. In the last part of the paper, reservoir models are used to characterize the water transfer and storage processes. Particular highlights are done on the advantages of continuous gravity data (compared to repeated campaigns) and on the importance of local accurate meteorological data to limit misinterpretation of the gravity observations. The results are complementary with previous studies at the basin scale and show a clear potential for continuous gravity time-series assimilation in hydrological simulations, even on heterogeneous karstic systems.
Surface deformation measured by geodetic data is the sum of single-strain sources deforming at depth. A combination of volume changes from several analytical models (e.g. a point source or ...dislocation along a plane) can be used to model the different sources. However, solving for the best fit of volume variations, dislocations, position and orientation parameters of all sources is a nonlinear problem, and its solution is generally non-unique. This problem can be converted into a linear one by assimilating the sum of sources to a simplified model formed by three orthogonal planes of dislocations at fixed position and orientation. This strain source model is equivalent to having all neighbouring deformation sources contained in a small size volume. The determination of the strain tensor components can be performed by inverting geodetic data. Because of their high resolution, tiltmeters are well adapted to survey shallow deformation of volcanoes and geological reservoirs. However, they are known to display unknown long-term drift. We propose an approach to jointly estimate the temporal evolution of the strain source and time-dependent instrumental parameters. We verify the approach using synthetic data, giving confidence intervals for each component of the strain tensor. Finally, we link geological information to the internal deformation by interpreting the strain tensor as principal directions of deformation. This approach seems promising for the identification of fracture onset and fault reactivation in geothermal, hydrocarbon exploitations or volcanic systems.
Borehole tiltmeters are widely used to continuously record small surface deformation of reservoirs and volcanoes. Because these instruments display unknown long-term drift, only short-term tilt ...signal can be used for monitoring purpose. We propose a method to invert long-term time series of tilt data induced by strain variations at depth. The assumption that tiltmeter drift is linear over time is on its own insufficient to remove the drift and uniquely determine the deformation source parameters. To overcome this problem, we first invert the data with no constrain on the drift to obtain one particular solution among all admissible. Then, using the linearity of the forward model, we use the statistical properties of the drift distributions to restore the uniqueness of the solution. We illustrate our approach with four synthetic cases simulating volume changes of a reservoir. We demonstrate the efficiency of our method and show that the accuracy of estimated volume variation dramatically improves if low drift tiltmeters are used.
Vaccines are the most effective mechanism for ending the COVID-19 pandemic. However, reluctance to accept vaccines has hindered the efforts of health authorities to combat the virus. In Haiti, as of ...July 2021, less than 1% of the country's population has been fully vaccinated in part due to vaccine hesitancy. Our goal was to assess Haitian attitudes toward COVID-19 vaccination and investigate the primary reasons for Moderna vaccine hesitancy. We conducted a cross-sectional survey across three rural Haitian communities, in September 2021. The research team used electronic tablets to collect quantitative data from 1,071 respondents, selected randomly across the communities. We report descriptive statistics and identify variables associated with vaccine acceptance using logistic regression built using a backward stepwise approach. Among 1,071 respondents, the overall acceptance rate was 27.0% (n = 285). The most common reason for vaccine hesitancy was "concern about side effects" (n = 484, 67.1%) followed by "concern about contracting COVID-19 from the vaccine" (n = 472, 65.4%). Three-quarters of respondents (n = 817) identified their healthcare workers as their most trustworthy source for information related to the vaccine. In the bivariate analysis, male gender (p = .06) and no history of drinking alcohol (p < .001) were significantly associated with being more likely to take the vaccine. In the final reduced model, only those with a history of drinking alcohol were significantly more likely to take the vaccine (aOR = 1.47 (1.23, 1.87) p < .001). The acceptance rate for the COVID-19 vaccine is low, and public health experts should design and strengthen vaccination campaigns to combat misinformation and public distrust.
The GPS velocity field of the present-day deformation in Iran is modeled using a 3-dimensional (3D) finite element approach. The deformation can be accommodated either by a continuum medium or by ...faults which are modeled using discontinuities with Coulomb-failure criteria. Depending on the fault friction, the deformation will be accommodated by the continuum medium or by the faults. Therefore, no a priori hypothesis on continuum or microplate behavior is assumed. In addition, geological fault slip rates are used to better determine the optimum model. The best model fitting both GPS and geological data shows quasi-rigid blocks within the deformation zone and low effective fault friction for the main Iranian strike slip faults. The mechanical behavior of the Iranian lithosphere seems to be partly controlled by the large strike slip faults. However, some deformation is still taken up by the continuum medium, suggesting a compromise between the microplate and continuum descriptions. Results also suggest localized shear zones in the mantle underneath the crustal faults bordering the quasi-rigid blocks. Lastly, the Arabia push relative to Eurasia explains most of the kinematics in Iran, but the complex velocity field of the surrounding South Caspian basin cannot be fitted by this model. Therefore, slab pull due to a remnant oceanic crust may occur in the Caucasus–Caspian region.
Measurements on either side of the Kazerun fault system in the Zagros Mountain Belt, Iran, show that the accommodation of the convergence of the Arabian and Eurasian Plates differs across the region. ...In northwest Zagros, the deformation is partitioned as 3–6 mm yr−1 of shortening perpendicular to the axis of the mountain belt, and 4–6 mm yr−1 of dextral strike-slip motion on northwest–southeast trending faults. No individual strike-slip fault seems to slip at a rate higher than ∼2 mm yr−1. In southeast Zagros, the deformation is pure shortening of 8 ± 2 mm yr−1 occurring perpendicular to the simple folded belt and restricted to the Persian Gulf shore. The fact that most of the deformation is located in front of the simple folded belt, close to the Persian Gulf, while seismicity is more widely spread across the mountain belt, confirms the decoupling of the surface sedimentary layers from the seismogenic basement. A comparison with the folding and topography corroborates a southwestward propagation of the surface deformation. The difference in deformation between the two regions suggests that right-lateral shear cumulates on the north–south trending Kazerun strike-slip fault system to 6 ± 2 mm yr−1.
In this paper, we investigate the impact of ambient temperature changes on the gravity reading of spring-based relative gravimeters. Controlled heating experiments using two Scintrex CG5 gravimeters ...allowed us to determine a linear correlation (
R
2
>
0.9) between ambient temperature and gravity variations. The relation is stable and constant for the two CG5 we used: −5 nm/s
2
/
∘
C. A linear relation is also seen between gravity and residual sensor temperature variations (
R
2
>
0.75), but contrary to ambient temperature, this relation is neither constant over time nor similar between the two instruments. The linear correction of ambient temperature on the controlled heating time series reduced the standard deviation at least by a factor of 2, to less than 10 nm/s
2
. The laboratory results allowed for reprocessing the data gathered on a field survey that originally aimed to characterize local hydrological heterogeneities on a karstic area. The correction of two years of monthly CG5 measurements from ambient temperature variations halved the standard deviation (from 62 to 32 nm/s
2
) and led us to a better hydrological interpretation. Although the origin of this effect is uncertain, we suggest that an imperfect control of the sensor temperature may be involved, as well as a change of the properties of an electronic component.
Contrasted tectonic styles occur in northern Iran. West of Kopet Dagh, the south Caspian basin is an aseismic and possibly rigid block involved in the collision zone between Eurasia and Arabia. To ...the NW, large scale velocity field of Iran given by recent repeated GPS surveys suggests ∼8 mm/yr of right-lateral displacement for the WNW–ESE faults in the Tabriz region. More surprisingly, geodetic motion also suggests a prominent N 30° extension north to the Tabriz fault where compression would be expected.
In order to quantify more precisely the right-lateral movement of the Tabriz region, the extension of NW Iran and the motion of the south Caspian basin, we deployed a dense GPS network in NW Iran, from Central Iran to the Turkish, Armenian and Azerbaijan borders. Three repeated surveys from 2002 to 2004 assess that the Tabriz fault concentrates entirely the ∼8 mm/yr of right-lateral movement observed in NW Iran. This rate is in good agreement with a recurrence interval time of 250–300 yr proposed from historical seismicity studies. We found also two zones of extension, one just north of the Tabriz fault in the south of the Talesh plateau and another close from the Azerbaijan border north of the Talesh plateau. We suggest that the existence of a northward subduction of the south Caspian Basin could explain such an extension in the core of the Arabia–Eurasia collision. Increasing evidences of quaternary extensional tectonics in the region from Armenia to Alborz may lead to significantly alter our understanding of the northern Iran tectonics and challenge the traditional Arabian indenter plate tectonics.
Intestinal ostomy can have significant effects on lives and lived experiences. However, limited research exists on the experiences of persons with ostomy in low-resource settings, such as rural ...Haiti. This study aimed to explore the lived experiences of Haitians with an ostomy, focusing on the physical, psychological, and social aspects of their post-operative lives. We conducted 9 semi-structured, in-depth interviews with participants who had undergone ostomy surgery at the Hôpital Universitaire de Mirebalais in Haiti. Employing interpretative phenomenological analysis (IPA), we iteratively examined transcripts to identify convergent and divergent codes, which were then grouped into themes to better understand the participants' experiences. Three themes emerged: (a) ostomy as a social disease, which has severe impacts on relationships and place in society; (b) ostomy as altering self-image, leading participants to reflect on their identity and the underlying causes of their condition and to reevaluate their necessities and abilities; and (c) ostomy as an arduous medical journey, characterized by pain, distress, uncertainty, and disillusionment, but also resiliency, improvisation, and hope. This study highlights the multifaceted experiences of persons with ostomy in the low-resource rural environment of Haiti and underscores the need for improved access to medical care, financial support, and psychosocial and caregiving resources for these individuals. Findings also emphasize the importance of medical providers' improved understanding in making medical decisions, and cultural and socioeconomic factors in developing effective support strategies.
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