Hasil untuk "Dynamic and structural geology"

Kokorina, Tatyana A., Gon, Ruslan T.

This study presents, for the first time, a comprehensive typological classification and mapping of the littoral landscapes in the eastern part of Salmon Bay (Aniva Bay, the Sea of Okhotsk, southern coast of Sakhalin Island), using methods of underwater landscape (bentema) typology developed for the Sea of Japan (according B.V. Preobrazhensky et al.). The research utilized data collected in the intertidal zone, which provided a representative sampling of relief forms, substrate types and skeletal content, as well as the state of the macrobenthos. Seven main types of bentema are described: metagest, skatebra, fractum, segetium, arenoid, peltium, and saxosium. For each landscape type, key morphological, granulometric, and biotic parameters are provided, as well as the main edificators and characteristic species. The study found that traces of organism activity (vestigial features) contribute to a more accurate determination of landscape boundaries. The results demonstrate the possibility of adapting the sublittoral bentema typology to the littoral zone and confirm its effectiveness for the recognition and structurally mapping of the dynamic coastal ecosystems. The classification system, which integrates physicogeographical and biotic parameters, can be used to monitor the state of coastal ecosystems and conduct comparative studies in coastal waters, as well as to objectively map the landscapes of the littoral.

C. Fenske, C. Fenske, J. Braun et al.

<p>Duricrusts form near the top of or within the regolith. Once exhumed, they are resistant to erosion and are often observed capping hilltops. Two hypotheses have been proposed to explain their formation. One calls upon seasonal fluctuations in water table height causing cycles of dissolution and precipitation that concentrate hardening species transported from distant sources. The other assumes that hardening is the ultimate phase of laterisation of the regolith by progressive leaching of the soluble elements that leads to in situ concentration of the hardening species. Here we propose a numerical model for the formation of duricrusts following the latter hypothesis, which we will term the in situ or laterisation (LAT) model. In <span class="cit" id="xref_text.1"><a href="#bib1.bibx36">Fenske et al.</a> (<a href="#bib1.bibx36">2025</a>)</span>, we developed a similar model representing the other model (named here the transport or Water Table Fluctuation (WTF) model).</p> <p>The LAT model we present here assumes that the rate of hardening is a self-limiting process that takes place at a rate determined by a laterisation time scale, <span class="inline-formula"><i>τ</i>_l</span>, and is linearly proportional to precipitation rate. Laterisation is accompanied by mass loss, at a rate set by a mass loss time scale, <span class="inline-formula"><i>τ</i>_m</span>, that can potentially be different from <span class="inline-formula"><i>τ</i>_l</span> and causes lowering of the topographic surface. We also test three laterisation modes, that depend on whether laterisation takes place above the water table only (percolation mode), below the water table (saturated mode) or everywhere (everywhere mode). This model for the formation of duricrusts is embedded in a previously published model for regolith formation <span class="cit" id="xref_paren.2">(<a href="#bib1.bibx18">Braun et al.</a>, <a href="#bib1.bibx18">2016</a>)</span>.</p> <p>Here we present results obtained from the new LAT model by varying both the model parameters and the external forcing functions, namely, <span class="inline-formula"><i>U</i></span> the uplift rate and <span class="inline-formula"><i>P</i></span>, the precipitation rate. We show that duricrust formation by laterisation is favored by a small uplift rate as well as a strong precipitation rate. The smaller the laterisation time scale and the mass loss time scale, the thicker the duricrust, but if the ratio between the two time scales, <span class="inline-formula"><i>τ</i>_m</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="36bd7baae116a5efc17e692d563c2b51"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-14-141-2026-ie00001.svg" width="8pt" height="14pt" src="esurf-14-141-2026-ie00001.png"/></svg:svg></span></span> <span class="inline-formula"><i>τ</i>_l</span> is too small, no duricrust can form or, in the saturated mode, the duricrust is progressively buried during its formation. We also derive a simple analytical expression for the conditions under which a duricrust will form within a regolith. This relationship implies that, as shown in <span class="cit" id="xref_text.3"><a href="#bib1.bibx18">Braun et al.</a> (<a href="#bib1.bibx18">2016</a>)</span>, for regolith to form, the time scale for primary weathering, <span class="inline-formula"><i>τ</i>_w</span>, that controls the rate of propagation of the weathering front into the bedrock must be smaller than the erosion time scale, <span class="inline-formula"><i>τ</i>_e</span>, that controls the rate of surface erosion, and for a duricrust to form, the time scale for secondary weathering, or laterisation time scale, <span class="inline-formula"><i>τ</i>_l</span>, must be smaller than the primary weathering time scale.</p> <p>The model also predicts hardening (or duricrust) age distributions that can be compared to ages obtained by (U-Th) <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="6bfc4ae3491d603d986b6e1d0e6866cf"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-14-141-2026-ie00002.svg" width="8pt" height="14pt" src="esurf-14-141-2026-ie00002.png"/></svg:svg></span></span> He dating of goethite in ferricretes for example. We show that these age distributions can be used to differentiate between the different modes of laterisation. We also show how peaks in age distributions appear to correlate very well with climatic events, but not with periods of enhanced uplift (or base level fall). The model also predicts the total mass loss by chemical vs. physical erosion. We show that the ratio between the two is mostly a function of the laterisation time scale and how it varies during climate or tectonic cycles.</p> <p><span id="page142"/>Finally, we show how the model predictions can be compared to those of the WTF model to help determine by which process a given duricrust formed. We also show, however, that there might be situations where the geometry, thickness and position of the duricrusts may not be unequivocal signatures of a given process.</p>

Yanyun Zhang, Yu Zhang, Huazheng Su et al.

This paper focuses on the Qinghai-Xizang Plateau. It systematically reviews its seismic activity characteristics and extensive environmental effects under extreme climatic conditions in dry and cold seasons. Firstly, through detailed data analysis and literature review, it is revealed how the seasonal significant rainfall and temperature changes in the plateau establish potential links with key parameters such as the frequency and intensity of seismic activity. This process deeply analyzes how natural conditions such as extreme rainfall and temperature changes directly or indirectly affect the mechanism of earthquake preparation and triggering, which may promote or inhibit the occurrence of seismic activity. The close relationship between cold and dry seasons and seismic activity is emphasized, and the unique influence of these special climatic conditions on seismic activity patterns is discussed. In addition, the regional distribution characteristics of seismic activity in the plateau area are also analyzed, including key data such as annual occurrence number and magnitude distribution, which provides strong data support for formulating regional earthquake disaster response strategies. In addition, the characteristics of various secondary disasters that may be caused by earthquakes, such as landslides, debris flows, barrier lakes, etc., are analyzed, which deepens the understanding of the complexity of the earthquake disaster chain. The aim is to provide a scientific basis for future earthquake disaster prevention and control work and to promote the improvement of earthquake science research and disaster management levels in the Qingzang Plateau and even the world.

Burak Aydin, Emre Parmaksiz, Ronnie Sircar

We study the dynamic pricing of discrete goods over a finite selling horizon. One way to capture both the elastic and stochastic reaction of purchases to price is through a model where sellers control the intensity of a counting process, representing the number of sales thus far. The intensity describes the probabilistic likelihood of a sale, and is a decreasing function of the price a seller sets. A classical model for ticket pricing, which assumes a single seller and finite time horizon, is by Gallego and van Ryzin (1994) and it has been widely utilized by airlines, for instance. Extending to more realistic settings where there are multiple sellers, with finite inventories, in competition over a finite time horizon is more complicated both mathematically and computationally. We introduce a dynamic mean field game of this type, and some numerical and existence results. In particular, we analyze the associated coupled system of Hamilton-Jacobi-Bellman and Kolmogorov differential-difference equations, and we prove the existence and uniqueness results under certain conditions. Then, we demonstrate a numerical algorithm to find this solution and provide some insights into the macroeconomic market parameters. Finally, we present a qualitative comparison of our findings with airfare data.

S. Polanco, M. Blum, T. Salles et al.

<p>The interplay between climate-forced sea level change, erosional and depositional processes, and flexural isostasy in deep time on passive margin deltas remains poorly understood. We performed a series of conceptual simulations to investigate flexural isostatic responses to high-frequency fluctuations in water and sediment load associated with climatically driven sea level changes. We model a large drainage basin that discharges to a continental margin and produces a large deltaic depocenter, then prescribe synthetic and climatic-driven sea level curves of different frequencies to assess flexural response. Results show that flexural isostatic responses are bidirectional over 100–1000 kyr timescales and are in sync with the magnitude, frequency, and direction of sea level fluctuations and that isostatic adjustments play an important role in driving along-strike and cross-shelf river mouth migration and sediment accumulation. Our findings demonstrate that climate-forced sea level changes produce a feedback mechanism that results in self-sustaining creation of accommodation into which sediment is deposited and plays a major role in delta morphology and stratigraphic architecture.</p>

J. L. Fernández, A. M. Ferreiro, J. A. García et al.

For the calibration of the parameters in static and dynamic SABR stochastic volatility models, we propose the application of the GPU technology to the Simulated Annealing global optimization algorithm and to the Monte Carlo simulation. This calibration has been performed for EURO STOXX 50 index and EUR/USD exchange rate with an asymptotic formula for volatility or Monte Carlo simulation. Moreover, in the dynamic model we propose an original more general expression for the functional parameters, specially well suited for the EUR/USD exchange rate case. Numerical results illustrate the expected behavior of both SABR models and the accuracy of the calibration. In terms of computational time, when the asymptotic formula for volatility is used the speedup with respect to CPU computation is around $200$ with one GPU. Furthermore, GPU technology allows the use of Monte Carlo simulation for calibration purposes, the computational time with CPU being prohibitive.

John Augustine, Antonio Cruciani, Iqra Altaf Gillani

We study robust and efficient distributed algorithms for building and maintaining distributed data structures in dynamic Peer-to-Peer (P2P) networks. P2P networks are characterized by a high level of dynamicity with abrupt heavy node \emph{churn} (nodes that join and leave the network continuously over time). We present a novel algorithm that builds and maintains with high probability a skip list for $poly(n)$ rounds despite $\mathcal{O}(n/\log n)$ churn \emph{per round} ($n$ is the stable network size). We assume that the churn is controlled by an oblivious adversary (that has complete knowledge and control of what nodes join and leave and at what time and has unlimited computational power, but is oblivious to the random choices made by the algorithm). Moreover, the maintenance overhead is proportional to the churn rate. Furthermore, the algorithm is scalable in that the messages are small (i.e., at most $polylog(n)$ bits) and every node sends and receives at most $polylog(n)$ messages per round. Our algorithm crucially relies on novel distributed and parallel algorithms to merge two $n$-elements skip lists and delete a large subset of items, both in $\mathcal{O}(\log n)$ rounds with high probability. These procedures may be of independent interest due to their elegance and potential applicability in other contexts in distributed data structures. To the best of our knowledge, our work provides the first-known fully-distributed data structure that provably works under highly dynamic settings (i.e., high churn rate). Furthermore, they are localized (i.e., do not require any global topological knowledge). Finally, we believe that our framework can be generalized to other distributed and dynamic data structures including graphs, potentially leading to stable distributed computation despite heavy churn.

R. Vernooij, T. Eames, J. Russell-Smith et al.

<p><span id="page1040"/>Landscape fires, predominantly found in the frequently burning global savannas, are a substantial source of greenhouse gases and aerosols. The impact of these fires on atmospheric composition is partially determined by the chemical breakup of the constituents of the fuel into individual emitted chemical species, which is described by emission factors (EFs). These EFs are known to be dependent on, amongst other things, the type of fuel consumed, the moisture content of the fuel, and the meteorological conditions during the fire, indicating that savanna EFs are temporally and spatially dynamic. Global emission inventories, however, rely on static biome-averaged EFs, which makes them ill-suited for the estimation of regional biomass burning (BB) emissions and for capturing the effects of shifts in fire regimes. In this study we explore the main drivers of EF variability within the savanna biome and assess which geospatial proxies can be used to estimate dynamic EFs for global emission inventories. We made over 4500 bag measurements of CO<span class="inline-formula">₂</span>, CO, CH<span class="inline-formula">₄</span>, and N<span class="inline-formula">₂</span>O EFs using a UAS and also measured fuel parameters and fire-severity proxies during 129 individual fires. The measurements cover a variety of savanna ecosystems under different seasonal conditions sampled over the course of six fire seasons between 2017 and 2022. We complemented our own data with EFs from 85 fires with locations and dates provided in the literature. Based on the locations, dates, and times of the fires we retrieved a variety of fuel, weather, and fire-severity proxies (i.e. possible predictors) using globally available satellite and reanalysis data. We then trained random forest (RF) regressors to estimate EFs for CO<span class="inline-formula">₂</span>, CO, CH<span class="inline-formula">₄</span>, and N<span class="inline-formula">₂</span>O at a spatial resolution of 0.25<span class="inline-formula">^∘</span> and a monthly time step. Using these modelled EFs, we calculated their spatiotemporal impact on BB emission estimates over the 2002–2016 period using the Global Fire Emissions Database version 4 with small fires (GFED4s). We found that the most important field indicators for the EFs of CO<span class="inline-formula">₂</span>, CO, and CH<span class="inline-formula">₄</span> were tree cover density, fuel moisture content, and the grass-to-litter ratio. The grass-to-litter ratio and the nitrogen-to-carbon ratio were important indicators for N<span class="inline-formula">₂</span>O EFs. RF models using satellite observations performed well for the prediction of EF variability in the measured fires with out-of-sample correlation coefficients between 0.80 and 0.99, reducing the error between measured and modelled EFs by 60 %–85 % compared to using the static biome average. Using dynamic EFs, total global savanna emission estimates for 2002–2016 were 1.8 % higher for CO, while CO<span class="inline-formula">₂</span>, CH<span class="inline-formula">₄</span>, and N<span class="inline-formula">₂</span>O emissions were, respectively, 0.2 %, 5 %, and 18 % lower compared to GFED4s. On a regional scale we found a spatial redistribution compared to GFED4s with higher CO, CH<span class="inline-formula">₄</span>, and N<span class="inline-formula">₂</span>O EFs in mesic regions and lower ones in xeric regions. Over the course of the fire season, drying resulted in gradually lower EFs of these species. Relatively speaking, the trend was stronger in open savannas than in woodlands, where towards the end of the fire season they increased again. Contrary to the minor impact on annual average savanna fire emissions, the model predicts localized deviations from static averages of the EFs of CO, CH<span class="inline-formula">₄</span>, and N<span class="inline-formula">₂</span>O exceeding 60 % under seasonal conditions.</p>

A. Dietmaier, T. Baumann

<p>Geothermal waters provide a great resource to generate clean energy, however, there is a notorious lack of high quality data on these waters. The scarcity of deep geothermal aquifer information is largely due to inaccessibility and high analysis costs. However, multiple operators use geothermal wells in Lower Bavaria and Upper Austria for balneological (medical and wellness) applications as well as for heat mining purposes. The state of the art sampling strategy budgets for a sampling frequency of 1 year. Previous studies have shown that robust groundwater data requires sampling intervals of 1–3 months, however, these studies are based on shallow aquifers which are more likely to be influenced by seasonal changes in meteorological conditions. This study set out to assess whether yearly sampling adequately represents sub-yearly hydrochemical fluctuations in the aquifer by comparing yearly with quasi-continuous hydrochemical data at two wells in southeast Germany by assessing mean, trend and seasonality detection among the high and low temporal resolution data sets. Furthermore, the ability to produce reliable forecasts based on yearly data was examined. In order to test the applicability of virtual sensors to elevate the information content of yearly data, correlations between the individual parameters were assessed. The results of this study show that seasonal hydrochemical variations take place in deep aquifers, and are not adequately represented by yearly data points, as they are typically gathered at similar production states of the well and do not show varying states throughout the year. Forecasting on the basis of yearly data does not represent the data range of currently measured continuous data. The limited data availability did not allow for strong correlations to be determined. We found that annual measurements, if taken at regular intervals and roughly the same production rates, represent only a snapshot of the possible hydrochemical compositions. Neither mean values, trends nor seasonality was accurately captured by yearly data. This could lead to a violation of stability criteria for mineral water, or to problems in the geothermal operation (scalings, degassing). We thus recommend a new testing regime of at least 3 samples a year. While not a replacement for the detailed analyses, under the right circumstances, and when trained with more substantial data sets, viertual sensors provide a robust method in this setting to trigger further actions.</p>

M. de Michele, D. Raucoules, C. Rault et al.

<p>This study examines the results of an interferometric synthetic aperture radar (InSAR) and SAR offset tracking (OT) study in Cirque de Salazie (CdS), Réunion Island, France, within the context of the RENOVRISK project, a multidisciplinary programme to study the cyclonic risks in the south-western Indian Ocean. Despite numerous landslides in this territory, CdS is one of the more densely populated areas on Réunion Island. One of the aims of the project is to assess whether Sentinel-1 SAR methods can be used to measure landslide motion and/or accelerations due to post-cyclonic activity in CdS. We concentrate on the post-2017 cyclonic activity. We use the Copernicus Sentinel-1 data, acquired between 30 October 2017 and 6 November 2018. Sentinel-1 is a C-band SAR, and its signal can be severely affected by the presence of changing vegetation between two SAR acquisitions, particularly in CdS, where the vegetation canopy is well developed. This is why C-band radars such as the ones on board RADARSAT or Envisat, characterized by low acquisition frequency (24 and 36 d, respectively), could not be routinely used in CdS to measure landslide motion with InSAR in the past. In this study, we use InSAR and OT techniques applied to Sentinel-1 SAR. We find that C-band SAR on board Sentinel-1 can be used to monitor landslide motion in densely vegetated areas, thanks to its high acquisition frequency (12 d). OT stacking reveals a useful complement to InSAR, especially in mapping fast moving areas. In particular, we can highlight ground motion in the Hell-Bourg, Ilet à Vidot, Grand-Ilet, Camp Pierrot, and Le Bélier landslides.</p>

György Hetényi, Shiba Subedi

Earthquakes in Nepal are among the most damaging natural hazards, claiming many lives and causing more widespread destruction than any other natural hazard. Yet, due to other difficulties and challenges, earthquakes are at the forefront of people’s attention only after major events, such as the 1934 or 2015 earthquakes. As a result, current preparedness of the population to earthquakes is far below the optimal level. This calls for an immediate and widespread educational effort to increase awareness and to raise the current young generation responsibly. After describing the current status of earthquake education at various school levels in Nepal, we here propose a series of actions to undertake towards an official education policy, starting from full openness and use of languages, via coordination and teacher's training, to the content, frequency and style of curriculum. We conclude on a timeline of actions, which have various lengths but should start today. We hope that by sharing our researcher and educational experience and thoughts, the actual preparation of the earthquake education policy for Nepal will start being developed under a dedicated team. Elements of the proposal presented here can be used and adapted to other regions at risk around the world.

Marta Milewska, Remco van der Hofstad, Bert Zwart

Random intersection graphs containing an underlying community structure are a popular choice for modelling real-world networks. Given the group memberships, the classical random intersection graph is obtained by connecting individuals when they share at least one group. We extend this approach and make the communities dynamic by letting them alternate between an active and inactive phase. We analyse the new model, delivering results on degree distribution, local convergence, giant component, and maximum group size, paying particular attention to the dynamic description of these properties. We also describe the connection between our model and the bipartite configuration model, which is of independent interest.

N. Kasyanova, Shuxin Qiu

Background. The role of dynamocatagenesis in oil and gas formation has been confirmed in a number of publications. However, all of them indicate that dynamocatagenesis manifestations are associated with tectonic disorders selectively. It remains unclear which morphodynamic characteristics of tectonic disorders relate to dynamocatagenesis manifestations, and which values the actual quantitative characteristics of dynamocatagenesis manifestations obtain. Research in this direction is of importance for assessing oil and gas formation in any area, particularly when forecasting unconventional oil and gas resources.Aim. To determine the reasons for the appearance of anomalies recorded in the deep zonality of the catagenetic transformation of organic matter within the Chezhen Sag of the Bohai oil and gas basin in order to understand conditions for the formation of hydrocarbons.Materials and methods. Studies were conducted at the borehole level, based on a comprehensive analysis of the latest geological, geophysical, and geochemical information obtained by the Sinopec Shengli Oilfield Company.Results. At the borehole level, the dynamic type of catagenesis of organic matter was established. A structural-kinematic-age characteristic of faults, to which dynamocatagenesis manifestations are confined, was described. Actual quantitative expressions of thermal impact of faults on the rocks of sedimentary strata were determined.Conclusion. The conducted research confirmed that anomalies in the deep zonality of organic matter catagenesis are related to dynamocatagenesis manifestations, rather than to the regional immersion.

Uta Rösel, Dietmar Drummer

Polymer-bonded magnets have increased significantly in the application of drive technology, especially in terms of new concepts for the magnetic excitation of synchronous or direct current (DC) machines. To satisfy the increasing demand of hard magnetic filler particles and especially rare earth materials in polymer-bonded magnets, different strategies are possible. In addition to the reduction in products or the substitution of filler materials, the recycling of polymer-bonded magnets is possible. Different strategies have to be distinguished in terms of the target functions such as the recovery of the matrix material, the filler or both materials. In terms of polymer-bonded magnets, the filler material—especially regarding rare earth materials—is important for the recycling strategy due to the limited resource and high costs. This paper illustrates two different recycling strategies relative to the matrix system of polymer-bonded magnets. For thermoset-based magnets, a thermal strategy is portrayed which leads to similar magnetic properties in terms of the appropriated atmosphere and process management. The mechanical reusage of shreds is analyzed for thermoplastic-based magnets. The magnetic properties are reduced by about 20% and there is a change in the flow conditions and with that, an influence on the pole accuracy.

Konan Hara, Yuki Ito, Paul Koh

We develop an empirical framework for analyzing dynamic games when the underlying information structure is unknown to the analyst. We introduce \textit{Markov correlated equilibrium}, a dynamic analog of Bayes correlated equilibrium, and show that its predictions coincide with the Markov perfect equilibrium predictions attainable when players observe richer signals than the analyst assumes. We provide tractable methods for informationally robust estimation, inference, and counterfactual analysis. We illustrate the framework with a dynamic entry game between Starbucks and Dunkin' in the US and study the role of informational assumptions.

Catalina Luneburg, Hermann Lebit, Stefano Mazzoli et al.

Lyu Pengfei, Lu Jiabin, Wang Eryu et al.

Coal mine rockburst is closely related to the complex geological structure. Understanding the criterion of the fault activation instability and the disaster-causing mechanism of rockburst under the influence of mining is the theoretical premise and important guarantee of safe and efficient coal mining. In this paper, based on the theory of key stratum, the mechanical model of fault slip instability in the normal fault during the hanging wall mining was established, and the instability criterion was derived. It is concluded that the fault slip instability of the hanging wall is mainly controlled by two factors: (1) the distance between coal seams and key stratum and (2) the distance between working face and fault. Moreover, these two factors have an inverse relation to the occurrence of rockburst. Subsequently, three conceptual models of rockburst induced by the fault stress transfer, stress concentration of coal pillars, and fault structural instability were proposed. Based on the rock mechanics theory, the rockburst carrier system model of “roof-coal seam-floor” near the fault was established. The mechanical essence of fault rockburst was obtained as follows: under the action of fault, the static load of fault coal pillar was increased and superimposed with the fault activation dynamic load, leading to high-strength rockburst disaster. Based on the occurrence mechanism of fault rockburst, the monitoring and prevention concept and technical measures were proposed in three aspects, including the monitoring and control of fault activation dynamic loads, the monitoring of high static load in fault coal pillar and stress release, and the strengthening roadway support. These prevention and control measures were verified in the panel 103down02 of the Baodian Coal Mine in engineering, and the effectiveness of these measures was proved.

M. Haag, Rayane Bastos de Freitas, C. Sommer et al.

Abstract Rhyolites compose an important record in the volcanic history of Earth, with significant occurrences in volcanic arcs, large igneous provinces and post-collisional terranes, often associated with explosive events. In several geologic provinces, rhyolites dominate as the most expressive geologic units (e.g., Silicic Large Igneous Provinces - SLIPs). Despite their importance, several aspects related to the emplacement of rhyolite flows are still enigmatic. Recent studies in modern rhyolite lavas suggest similar emplacement mechanisms to basaltic lavas, implying a more dynamic growth model for silicic flows, including outbreak lobes and outpour structures. Despite these advances, studies related to the recognition of these features in ancient flows are still rare. In this work we perform a multi-proxy study of an ancient (Neoproterozoic) rhyolitic lava flow combining fieldwork, petrography, geochemistry, rheology and magnetic fabric analysis. The Cerro do Perau outcrop (CP, southern Brazil) consists of a natural laboratory for the study of rhyolite lavas, presenting excellent exposure of a partially preserved flow with distinct flow features and folds. CP flow consists of a high-silica and low-crystal content rhyolite, suggesting its emplacement as an obsidian flow. Rheology data indicates high liquidus temperatures (>957 °C), with maximum viscosities of 108.5 Pa s and glass transition temperatures (Tg) of 750 °C. The absence of brittle features suggests little to none displacement below Tg. Structural analysis indicates the predominance of sub-vertical foliation planes, including axial planes of folds, indicative of proximal (near-vent) regions in rhyolite flows. The absence of lineations favors a predominantly planar accommodation of the flow-induced deformation, which is confirmed by the shape of the magnetic fabric ellipsoids. Several of these ellipsoids display a high degree of anisotropy, mostly related to an oblate fabric, indicative of the development of high-strain zones within the flow. Our data suggest that CP flow presents some similarities with recently proposed field-based emplacement models for rhyolitic flows, highlighting the significant data that can be extracted from a combination of magnetic fabrics and rheological analyses.

T. Eken, M. T. Qashqai, C. Schiffer et al.

Constraints on crustal and uppermost mantle structure provide key information for understanding the geodynamic processes that have shaped the geological expressions and are currently causing deformation in Anatolia. We apply a novel method of Bayesian inversion of autocorrelated teleseismic P‐wave coda data to retrieve the crustal and uppermost mantle structures beneath Anatolia and southeast Europe. Our inversion provides estimates of Moho depth variations and crustal velocity structure (e.g., Vp, Vs, and Vp/Vs ratio). The Moho architecture in the study area can be summarized by (a) an overall west‐to‐east increase in the Moho depth from Greece to eastern Anatolia, (b) a homogeneously thin crustal structure beneath Greece, (c) complex, small‐scale crustal features and variations in western and central Anatolia, and (d) relatively long‐wavelength variations, but overall thick crust in eastern Anatolia. The apparent relation between the Moho depth variations and suture/fault zones implies a dominant control of structural inheritance on the past deformation in Anatolia. The overall Moho architecture appears to correlate well with the topography in Anatolia, although with some exceptions, in particular at smaller wavelength. These local inconsistencies in the topography‐Moho depth relation suggest a more complex, wavelength‐dependent isostatic state compared to what is expected from simple Airy isostasy. The observed deviations may originate from elastic effects, lithospheric density changes, or sub‐lithospheric dynamic effects. Obvious large lateral variations in Vp, Vs and Vp/Vs ratio estimates in our model can relate to such density variations within the crust especially between tectonic domains.

Wang Jiaxu, Xue Yadong, Liu Xuhui et al.

Multi-source information monitoring and data fusion analysis system has high practical value for the risk management of tunnel structure, especially in complex ground. The analysis of structure health will be getting more comprehensive and real-time with multisource monitoring technologies. Risk warning will be more accurate and timelier. Based on one shield tunnel project, this research analysed the water leakage risk of shield subsea tunnel in unfavourable geological conditions by using the method of geological information and structural monitoring data fusion. Firstly, Kalman filter method was used to denoise the monitoring data, and the effect of different monitoring data was compared; Then, the risk factor of water leakage was analysed, and the relationship between risk factors, geological information and monitoring data was established; Finally, the risk factors based on multi-source monitoring information were fused and analysed by using the improved D-S evidence theory method, and the final analysis results of water leakage risk were obtained. A multisource dynamic risk analysis model of tunnel water leakage was established. The results showed that the Kalman filter method has better noise reduction effect on the high-frequency monitoring data than that of low-frequency monitoring data, and the multi-source dynamic risk analysis model has a good prediction effect on the water leakage risk of tunnel lining in unfavourable ground condition.