Observed and predicted earthquake damage scenarios: the case study of Pettino (L’Aquila) after the 6th April 2009 event

A damage scenario based on observational data collected in L’Aquila Municipality after the 6th April 2009 earthquake is compared with a predicted damage scenario derived from the application of a simplified analytical method for seismic vulnerability assessment of Reinforced Concrete (RC) buildings at large scale. The observational damage scenario is derived from a database of 131 RC buildings located in the Municipality of L’Aquila, which after the 2009 earthquake were subjected to post-earthquake usability assessment procedure. The simplified analytical approach adopted is based on the Capacity Spectrum Method to evaluate seismic capacity at different Damage States (DSs) based on the displacement capacity of structural and non-structural elements. DSs and the corresponding displacement capacity are defined through the interpretation of the observational-based DSs provided by the European Macroseismic Scale EMS-98. Data predicted by the adopted methodology are in good agreement with the observed damage distribution. The observed damage scenario is also compared with predicted scenarios derived from other methodologies from literature.     

Spatial Distribution of Carbonaceous Aerosol in the Southeastern Baltic Sea Region (Event of Grass Fires)

The aerosol chemical composition in air masses affected by large vegetation fires transported from the Kaliningrad region (Russia) and southeast regions (Belarus and Ukraine) during early spring (March 2014) was characterized at the remote background site of Preila, Lithuania. In this study, the chemical composition of the particulate matter was studied by high temporal resolution instruments, including an Aerosol Chemical Speciation Monitor (ACSM) and a seven-wavelength aethalo-meter. Air masses were transported from twenty to several hundred kilometres, arriving at the measurement station after approximately half a day of transport. The concentration-weighted trajectory analysis suggests that organic aerosol particles are mainly transported over the Baltic Sea and the continent (southeast of Belarus). Results show that a significant fraction of the vegetation burning organic aerosol is transformed into oxidised forms in less than a half-day. Biomass burning aerosol (BBOA) was quantified from the ACSM data using a positive matrix factorization (PMF) analysis, while its spatial distribution was evaluated using air mass clustering approach.     

Shifting styles of basaltic explosive activity during the 2002–03 eruption of Mt. Etna, Italy

The 2002–03 flank eruption of Etna was characterized by two months of explosive activity that produced copious ash fallout, constituting a major source of hazard and damage over all eastern Sicily. Most of the tephra were erupted from vents at 2750 and 2800 m elevation on the S flank of the volcano, where different eruptive styles alternated. The dominant style of explosive activity consisted of discrete to pulsing magma jets mounted by wide ash plumes, which we refer to as ash-rich jets and plumes. Similarly, ash-rich explosive activity was also briefly observed during the 2001 flank eruption of Etna, but is otherwise fairly uncommon in the recent history of Etna. Here, we describe the features of the 2002–03 explosive activity and compare it with the 2001 eruption in order to characterize ash-rich jets and plumes and their transition with other eruptive styles, including Strombolian and ash explosions, mainly through chemical, componentry and morphology investigations of erupted ash. Past models explain the transition between different styles of basaltic explosive activity only in terms of flow conditions of gas and liquid. Our findings suggest that the abundant presence of a solid phase (microlites) may also control vent degassing and consequent magma fragmentation and eruptive style. In fact, in contrast with the Strombolian or Hawaiian microlite-poor, fluidal, sideromelane clasts, ash-rich jets and plumes produce crystal-rich tachylite clasts with evidence of brittle fragmentation, suggesting that high groundmass crystallinity of the very top part of the magma column may reduce bubble movement while increasing fragmentation efficiency.     

Climate change and modelling of extreme temperatures in Switzerland

This study models maximum temperatures in Switzerland monitored in twelve locations using the generalised extreme value (GEV) distribution. The parameters of the GEV distribution are determined within a Bayesian framework. We find that the parameters of the underlying distribution underwent a substantial change in the beginning of the 1980s. This change is characterised by an increase both in the level and the variability. We assess the likelihood of the heat wave of the summer 2003 using the fitted GEV distribution by accounting for the presence of a structural break. The estimation results do suggest that the heat wave of 2003 is not that statistically improbable if an appropriate methodology is used for dealing with nonstationarity.     

Coastal hazard assessment and mapping in Northern Campania, Italy

In the Northern Campanian coastal zone, over 150 km long, three geomorphic units are recognised: (1) sandy beaches that are well developed in the northern area, where a prominent river mouth (Volturno River) is also present; (2) steep and rocky shores, often with gravelly beaches or debris cones at their base, are mainly diffuse in the southern area (Sorrentine Peninsula); and, lastly, (3) “techno coast”, shorelines stabilized with revetments and seawalls as well as former natural environments no longer clearly operational because of urbanization, as is visible in Naples and in the Vesuvian coast. Six primary hazards are considered in this investigation: shoreline erosion, riverine flooding, storms, landslides, seismicity and volcanism, and man-made structures. These hazards do not have a uniform distribution along this coast in terms of their frequency and intensity; moreover both their interaction and the intensive action of humans, often uncontrolled, makes it difficult to assess the overall coastal hazard. In this paper a semi-quantitative method with which to quantify, rank and map the distribution of hazard is applied along this particular stretch of coast. In such a stretch, previously characterized in terms of types and processes and compartmentalized into geomorphic units, the effect of individual hazards, based on their magnitude and recurrence, is evaluated. Dominant and subordinate hazards for each geomorphic unit are identified, assigning a rank that is also a weighting. Comparison of each weighting through an interaction matrix permits the calculation of a resultant, which is the overall hazard assessment and which can be expressed cartographically. The results obtained for a coastal zone with one of the highest pressures from urbanization in the world, help us to recognise that this approach could become a useful tool to aid decision-making regarding coastal land-use and planning.     

Effects of climate, invasive species and anthropogenic impacts on the growth of the seagrass Posidonia oceanica (L.) Delile in Liguria (NW Mediterranean Sea)

Eight shallow water Posidonia oceanica meadows were sampled in June 1999 along 300 km of the Ligurian coast and were compared through shoot density and lepidochronology. The growth of the seagrass was examined in the light of climate fluctuations and local stresses, colonisation by alien, invasive alga Caulerpa taxifolia, and effects of the oil spill from the tanker "Haven", and other anthropogenic impacts. Both shoot density and lepidochronology pointed to a generalised state of regression of all the meadows. The analysis of long-term growth curves of the rhizomes showed a positive trend parallel to the increase of air temperature. Two main groups of meadows were individuated on the basis of growth curve similarity. The first included four meadows, namely Ventimiglia, Imperia, Noli and Prelo, that were characterised by average values of rhizome growth of 8-9.1 mmyear(-1) and shoot density greater than 200 shootsm(-2). Although the Imperia meadow was the only one where the alien invasive alga C. taxifolia was found, it did not show differences for rhizome growth in comparison to the other meadows. The second group was formed by meadows that had suffered past anthropogenic impacts: Arenzano and Monterosso al Mare. They showed higher rhizome growth rates (9.4-10.6 mmyear(-1)) and shoot densities between 200 and 100 shootsm(-2). At Arenzano, where "Haven" oil was stranded in April 1991, no rhizome older than 8 years was found, thus confirming the shoot mortality induced by the oil spill event. The two last meadows exhibited growth curves very different from all the others: Portovenere, is a shallow meadow where P. oceanica merely survives in an extremely degraded situation with highest rhizome growth rate (12 mmyear(-1)), the other, Riva Trigoso, is the only meadow implanted on rock and had the lowest growth rates (7.1 mm year(-1)).     

Comparative soil CO2 flux measurements and geostatistical estimation methods on Masaya volcano, Nicaragua

We present a comparative study of soil CO₂ flux () measured by five groups (Groups 1–5) at the IAVCEI-CCVG Eighth Workshop on Volcanic Gases on Masaya volcano, Nicaragua. Groups 1–5 measured using the accumulation chamber method at 5-m spacing within a 900 m² grid during a morning (AM) period. These measurements were repeated by Groups 1–3 during an afternoon (PM) period. Measured ranged from 218 to 14,719 g m⁻² day⁻¹. The variability of the five measurements made at each grid point ranged from ±5 to 167%. However, the arithmetic means of fluxes measured over the entire grid and associated total CO₂ emission rate estimates varied between groups by only ±22%. All three groups that made PM measurements reported an 8–19% increase in total emissions over the AM results. Based on a comparison of measurements made during AM and PM times, we argue that this change is due in large part to natural temporal variability of gas flow, rather than to measurement error. In order to estimate the mean and associated CO₂ emission rate of one data set and to map the spatial distribution, we compared six geostatistical methods: arithmetic and minimum variance unbiased estimator means of uninterpolated data, and arithmetic means of data interpolated by the multiquadric radial basis function, ordinary kriging, multi-Gaussian kriging, and sequential Gaussian simulation methods. While the total CO₂ emission rates estimated using the different techniques only varied by ±4.4%, the maps showed important differences. We suggest that the sequential Gaussian simulation method yields the most realistic representation of the spatial distribution of , but a variety of geostatistical methods are appropriate to estimate the total CO₂ emission rate from a study area, which is a primary goal in volcano monitoring research.Editorial responsibility: H Shinohara