Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica
Summary: In this paper we characterise the flux and composition of the gas emissions from Turrialba Volcano. We show that the measured gas signature provides evidence that Turrialba Volcano has entered an open-vent configuration with magmatic gases being emitted. This suggests that the hydrothermal system at the summit is quickly drying up and that the system is moving from a hydrothermal to a magmatic end member with implications for short-term monitoring and possible evolution of the state of unrest.
Characterization and interaction of driving factors in karst rocky desertification: a case study from Changshun, China
Summary: Geographical information system techniques and a geographical-detector model are used to explore the relationship between the evolution of karst rocky desertiﬁcation (KRD) and driving data. Our results detect non-linearly enhanced impacts significantly aggravating the KRD. This implies that there is no significant difference between natural and anthropogenic factors influencing KRD improvement, and also that natural factors have a more important impact on KRD deterioration.
Microscale strain partitioning? Differential quartz crystallographic fabric development in Phyllite, Hindu Kush, Northwestern Pakistan
Summary: This study demonstrates the importance of spatial resolution and registration in specimens analysed for crystallographic fabric analyses. In the specimen examined, the bulk crystallographic orientation was dominated by one fabric. Yet it was two secondary, spatially distinct fabrics that yielded potentially important information on deformation temperature, paleopiezometry, and strain rate.
Relative tectonic activity classification in the Kermanshah area, western Iran
Summary: The Kermanshah area in the High Zagros, Iran (the collision of the Arabian and Eurasian plates) has been affected by four classes of tectonic variation. These regions were identified as very high, high, moderate and low relative tectonic activity by calculation and analysis of six geomorphic indices.
Future accreted terranes: a compilation of island arcs, oceanic plateaus, submarine ridges, seamounts, and continental fragments
Summary: Continents are composed of a collage of accreted terranes: tectonically sutured crustal units of various origins. This review covers the cycle of terrane accretion from the original entity (modern-day oceanic island arcs, oceanic plateaus, submarine ridges, seamounts, continental fragments, and microcontinents) to present-day examples of terrane accretion to finally allochthonous accreted terranes.
Tunable diode laser measurements of hydrothermal/volcanic CO2 and implications for the global CO2 budget
Summary: Here, we present the results of tunable diode laser observations at four quiescent volcanoes: Nea Kameni, Hekla, Krýsuvík, and Vulcano Island, which display a range of fumarolic activity from weak to moderate. This study contributes to better characterising the typical levels of CO2 emission from such feeble volcanic point sources, suggesting that the cumulative contribution from weakly degassing volcanoes may be significant at global scale.
Interpretative modelling of a geological cross section from boreholes: sources of uncertainty and their quantification
Summary: Geological information for users such as planners, miners or engineers depends on limited observations and the interpretative skills of the geologist. It therefore has an attendant uncertainty which must be quantified so that the data user can account for it. In this paper, we describe an experiment to identify and quantify the sources of uncertainty in geologists' interpretations of boreholes along a cross section.
Wave-equation-based travel-time seismic tomography – Part 2: Application to the 1992 Landers earthquake (Mw 7.3) area
Summary: The 1992 Landers earthquake area is chosen as the test field for the newly developed wave-equation based traveltime seismic tomography. The details of data selection, synthetic arrival-time determination, and trade-off analysis of damping and smoothing parameters are presented to show the performance of this tomographic inversion method. High-resolution crustal structures around the 1992 Lander earthquake area are obtained and help our understanding of the physical mechanism of the earthquakes.
Wave-equation-based travel-time seismic tomography – Part 1: Method
Summary: A wave-equation-based travel-time seismic tomography method is developed including a detailed description of its step-by-step process. The forward problem is solved in the two-dimensional (2-D) vertical plane passing through the source and the receiver, and the final model is parameterized on 3-D inversion grid nodes. This 2-D--3D tomography method takes into account finite-frequency effects, accurately simulates seismic wave propagation in complex media, and has great computational efficiency.
Finite lattice distortion patterns in plastically deformed zircon grains
Summary: Three types of lattice distortion patterns in deformed zircon are detected: (I) gradual bending of the crystal lattice without subgrain boundaries, (II) local gradual bending of the lattice with formation of semicircular subgrain boundaries, and (III) strain-free subgrains separated by subgrain boundaries. The difference is controlled by strain rate and differential stress. Activation of energetically preferable slip systems is facilitated by decoupling from matrix and/or by soft host mineral.
Using the level set method in geodynamical modeling of multi-material flows and Earth's free surface
Summary: Our paper demonstrates that the level set method is a viable method for material tracking in multi-material flow models. The different benchmarks illustate several advantages that the level set method provides over tracer-based methods. We therefore conclude that the level set method is well suited for geodynamical modeling.
Analysis of land cover change and its driving forces in a desert oasis landscape of Xinjiang, northwest China
Summary: In this paper, we present research on the spatial-temporal pattern of land cover change in the fragile ecosystem of the arid desert oasis of Hotan in northwest China. Multi-temporal Landsat images were used to analyze the land cover change and to identify change trajectories. The natural and human driving forces of these changes were examined using hydro-climatic data and socio-economic data.