The Son Poc rockfall (Mallorca,Spain) on the 6th of March 2013: 3D simulation

The Son Poc rockfall took place on the 6th of March 2013 in the municipality of Bunyola, on the southern side of the Tramuntana Range (Mallorca) and after a rainy and cold period on the region. A volume of rock of 4.000 m³ was detached from the cliff crowning the peak falling down by toppling. The impact of the boulder caused its fragmentation, and numerous boulders bounced and rolled downslope with volumes from 1 to 35 m³, following two trajectories: southwest (SW) and southeast (SE). The SE trajectory, with a larger runout (376 m), reached an urban area, where some of the boulders hit the roofs and walls of nearby houses, stopping others in their gardening areas. Fortunately, no fatalities occurred despite of the presence of some people at that moment, but the event caused great concern in a region which lives from and for tourism. The Son Poc rockfall has been simulated using RocPro3D software which uses GIS technology to produce 3D rockfall trajectories lines, estimated velocity and energy of falling blocks, as well as bounce heights, impacts, and stopping points. The results are in agreement with field observations and with a very good accuracy between real and modeled outcomes.     

Geometry and kinematics of the Roisan-Cignana Shear Zone,and the orogenic evolution of the Dent Blanche Tectonic System (Western Alps)

The Dent Blanche Tectonic System (DBTS) is a composite thrust sheet derived from the previously thinned passive Adriatic continental margin. A kilometric high-strain zone, the Roisan-Cignana Shear Zone (RCSZ) defines the major tectonic boundary within the DBTS and separates it into two subunits, the Dent Blanche s.s. nappe to the northwest and the Mont Mary nappe to the southeast. Within this shear zone, tectonic slices of Mesozoic and pre-Alpine meta-sediments became amalgamated with continental basement rocks of the Adriatic margin. The occurrence of high pressure assemblages along the contact between these tectonic slices indicates that the amalgamation occurred prior to or during the subduction process, at an early stage of the Alpine orogenic cycle. Detailed mapping, petrographic and structural analysis show that the Roisan-Cignana Shear Zone results from several superimposed Alpine structural and metamorphic stages. Subduction of the continental fragments is recorded by blueschist-facies deformation, whereas the Alpine collision is reflected by a greenschist facies overprint associated with the development of large-scale open folds. The post-nappe evolution comprises the development of low-angle brittle faults, followed by large-scale folding (Vanzone phase) and finally brittle extensional faults. The RCSZ shows that fragments of continental crust had been torn off the passive continental margin prior to continental collision, thus recording the entire history of the orogenic cycle. The role of preceding Permo-Triassic lithospheric thinning, Jurassic rifting, and ablative subduction processes in controlling the removal of crustal fragments from the reactivated passive continental margin is discussed. Results of this study constrain the temporal sequence of the tectono-metamorphic processes involved in the assembly of the DBTS, but they also show limits on the interpretation. In particular it remains difficult to judge to what extent pre-collisional rifting at the Adriatic continental margin preconditioned the efficiency of convergent processes, i.e. accretion, subduction, and orogenic exhumation.     

Potential effects of incoming climate changes on the behaviour of slow active landslides in clay

Today, a stimulating debate involves the scientific community about the impact of presumable future climate changes on the human life. One of the main question marks concerns their effects on hydrological hazards. Unfortunately, often such a debate is not based on reliable data. The paper proposes a methodology based on the coupling of climatic scenarios and geotechnical analyses accounting for the potential changes in climate parameters. Some analyses have been carried out to forecast the future behaviour of a slow landslide in clay. According to the adopted model, local climate effects should cause a slow decrease in the displacement rate.     

Desertification and erosion sensitivity. A case study in southern Italy: the Tusciano River catchment

The ESAs (Environmentally sensitive areas) procedure was recently developed in the framework of MEDALUS European project to identify desertification-sensitive areas and used in many Mediterranean countries (Greece, Portugal, Italy, Egypt). The identification of areas sensitive to desertification by using the ESAs model was carried out in the Tusciano River basin (261 km²) located in southern Italy (Campania region). All data characterizing the four groups of parameters related to soil quality, climate quality, vegetation quality and management quality were introduced in a geographical database, and superimposed using a GIS. A sensitivity analysis highlighted the impact of desertification on the river Tusciano catchment, highly diversified in terms of morphological, geological, climatic and land use features. The results of the ESAs model, showing that more than half of the area is sensitive to desertification, were compared with those related to soil loss, achieved by Revised Universal Soil Loss Equation, based approximately on the same environmental factors. Nevertheless, ESAs procedure considers a wider range of parameters, allowing to characterize in greater detail the catchment in terms of climate, geomorphology, vegetation cover and socio-economic features. The drawn map therefore characterizes the sensitivity to erosion/desertification of the Tusciano catchment and can be regarded as a synthesis-sensitivity map, showing the areas with higher vulnerability on which mitigation measures should be focused.     

The imaging and slitless spectroscopy instrument for surveys (ISSIS) for the world space observatory-ultraviolet (WSO-UV)

ISSIS is the Imaging and Slitless Spectroscopy Instrument for the World Space Observatory-Ultraviolet (WSO-UV) mission. ISSIS is a multipurpose instrument designed to carry out high resolution (<0.1 arcsec) imaging in the far UV with fields of view ≥2×2 arcmin². ISSIS has two acquisition channels: the High Sensitivity Channel (HSC) and the Channel for Surveys (CfS). The HSC is equipped with an MCP-type detector to guarantee high sensitivity in the 1150–1750 ? range and high rejection of lower energy radiation. The CfS is equipped with a large CCD detector (4k×4k) to obtain images from the far UV to the red (1150–8500 ?); the CfS is implemented to allow observing UV bright sources such as reflection nebulae or nearby massive star forming regions. The design drivers and the current status of the instrument are described in this contribution.     

Initial Calibration of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO)

The Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) is an array of four normal-incidence reflecting telescopes that image the Sun in ten EUV and UV wavelength channels. We present the initial photometric calibration of AIA, based on preflight measurements of the response of the telescope components. The estimated accuracy is of order 25%, which is consistent with the results of comparisons with full-disk irradiance measurements and spectral models. We also describe the characterization of the instrument performance, including image resolution, alignment, camera-system gain, flat-fielding, and data compression.     

Imprints of hydrocarbon-bearing basinal fluids on a karst system: mineralogical and fluid inclusion studies from the Buda Hills,Hungary

Calcite veins and related sulphate–sulphide mineralisation are common in the Buda Hills. Also, abundant hypogenic caves are found along fractures filled with these minerals pointing to the fact that young cave-forming fluids migrated along the same fractures as the older mineralising fluids did. The studied vein-filling paragenesis consists of calcite, barite, fluorite and sulphides. The strike of fractures is consistent—NNW–SSE—concluding a latest Early Miocene maximum age for the formation of fracture-filling minerals. Calcite crystals contain coeval primary, hydrocarbon-bearing- and aqueous inclusions indicating that also hydrocarbons have migrated together with the mineralising fluids. Hydrocarbon inclusions are described here for the first time from the Buda Hills. Mixed inclusions, i.e., petroleum with ‘water-tail’, were also detected, indicating that transcrystalline water migration took place. The coexistence of aqueous and petroleum inclusions permitted to establish the entrapment temperature (80°C) and pressure (85 bar) of the fluid and thus also the thickness of sediments, having been eroded since latest Early Miocene times, was calculated (800 m). Low salinity of the fluids (<1.7 NaCl eq. wt%) implies that hydrocarbon-bearing fluids were diluted by regional karst water. FT-IR investigations revealed that CO₂ and CH₄ are associated with hydrocarbons. Groundwater also contains small amounts of HC and related gases on the basin side even today. Based on the location of the paleo- and recent hydrocarbon indications, identical migration pathways were reconstructed for both systems. Hydrocarbon-bearing fluids are supposed to have migrated north-westward from the basin east to the Buda Hills from the Miocene on.     

The February 2010 large landslide at Maierato, Vibo Valentia, Southern Italy

A large landslide formed at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, at 1430?hours local time, when rapid failure occurred after several days of preliminary movements. The landslide has an area of 0.3?km², a runout distance of 1.2?km and an estimated volume of about 10?Mm³. The landslide caused nearly 2,300 inhabitants to be evacuated, with high economic losses. The most probable trigger of the landslide was the cumulative precipitation over the preceding 20?days (having a return period of more than 100?years), which followed a long period of 4?C5?months of heavy rainfall (of about 150% of the average rainfall of the period). This report presents a summary of our findings pertinent to the landslide??s activities based on our field investigations. In particular, this report covers (1) details of land deformation caused by the landslide, (2) geology pertinent to landslide development, (3) identification of the landslide mechanism and its triggering factors based on the analysis of the boring core specimens and landform features, as well as the available video of the event, and (4) preliminary evaluation of the stability of the original slope before the landslide using the finite element-based shear strength reduction method. The aim of the paper was to describe the landslide and explain its mechanism of occurrence.     

Storm surges in the Singapore Strait due to winds in the South China Sea

Among the semi-enclosed basins of the world ocean, the South China Sea (SCS) is unique in its configuration as it lies under the main southwest-northeast pathway of the seasonal monsoons. The northeast (NE) monsoon (November–February) and southwest (SW) monsoon (June–August) dominate the large-scale sea level dynamics of the SCS. Sunda Shelf at the southwest part of SCS tends to amplify Sea Level Anomalies (SLAs) generated by winds over the sea. The entire region, bounded by Gulf of Thailand on the north, Karimata Strait on the south, east cost of Peninsular Malaysia on the west, and break of Sunda Shelf on the east, could experience positive or negative SLAs depending on the wind direction and speed. Strong sea level surges during NE monsoon, if coincide with spring tide, usually lead to coastal floods in the region. To understand the phenomena, we analyzed the wind-driven sea level anomalies focusing on Singapore Strait (SS), laying at the most southwest point of the region. An analysis of Tanjong Pagar tide gauge data in the SS, as well as satellite altimetry and reanalyzed wind in the region, reveals that the wind over central part of SCS is arguably the most important factor determining the observed variability of SLAs at hourly to monthly scales. Climatological SLAs in SS are found to be positive, and of the order of 30 cm during NE monsoon, but negative, and of the order of 20 cm during SW monsoon. The largest anomalies are associated with intensified winds during NE monsoon, with historical highs exceeding 50 cm. At the hourly and daily time-scales, SLA magnitude is correlated with the NE wind speed over central part of SCS with an average time lag of 36–42 h. An exact solution is derived by approximating the elongated SCS shape with one-dimensional two-step channel. The solution is utilized to derive simple model connecting SLAs in SS with the wind speeds over central part of SCS. Due to delay of sea level anomaly in SS with respect to the remote source at SCS, the simplified solutions could be used for storm surge forecast, with a lead time exceeding 1 day.     

Slope instability induced by volcano-tectonics as an additional source of hazard in active volcanic areas: the case of Ischia island (Italy)

Ischia is an active volcanic island in the Gulf of Naples whose history has been dominated by a caldera-forming eruption (ca. 55 ka) and resurgence phenomena that have affected the caldera floor and generated a net uplift of about 900 m since 33 ka. The results of new geomorphological, stratigraphical and textural investigations of the products of gravitational movements triggered by volcano-tectonic events have been combined with the information arising from a reinterpretation of historical chronicles on natural phenomena such as earthquakes, ground deformation, gravitational movements and volcanic eruptions. The combined interpretation of all these data shows that gravitational movements, coeval to volcanic activity and uplift events related to the long-lasting resurgence, have affected the highly fractured marginal portions of the most uplifted Mt. Epomeo blocks. Such movements, mostly occurring since 3 ka, include debris avalanches; large debris flows (lahars); smaller mass movements (rock falls, slumps, debris and rock slides, and small debris flows); and deep-seated gravitational slope deformation. The occurrence of submarine deposits linked with subaerial deposits of the most voluminous mass movements clearly shows that the debris avalanches impacted on the sea. The obtained results corroborate the hypothesis that the behaviour of the Ischia volcano is based on an intimate interplay among magmatism, resurgence dynamics, fault generation, seismicity, slope oversteepening and instability, and eruptions. They also highlight that volcano-tectonically triggered mass movements are a potentially hazardous phenomena that have to be taken into account in any attempt to assess volcanic and related hazards at Ischia. Furthermore, the largest mass movements could also flow into the sea, generating tsunami waves that could impact on the island’s coast as well as on the neighbouring and densely inhabited coast of the Neapolitan area.