Transient seismicity at active volcanoes poses a significant risk in addition to eruptive activity. This risk is powered by the common belief that volcanic seismicity cannot be forecast, even on a ...long term. Here we investigate the nature of volcanic seismicity to try to improve our forecasting capacity. To this aim, we consider Ischia volcano (Italy), which suffered similar earthquakes along its uplifted resurgent block. We show that this seismicity marks an acceleration of decades‐long subsidence of the resurgent block, driven by degassing of magma that previously produced the uplift, a process not observed at other volcanoes. Degassing will continue for hundreds to thousands of years, causing protracted seismicity and will likely be accompanied by moderate and damaging earthquakes. The possibility to constrain the future duration of seismicity at Ischia indicates that our capacity to forecast earthquakes might be enhanced when seismic activity results from long‐term magmatic processes, such as degassing
Plain Language Summary
Seismic events that take place in volcanic areas are influenced by multiple volcanic processes, so seismicity is difficult to forecast. Sometimes seismicity may follow a recurrent behavior in time and mechanism. Therefore, understanding the main processes active at volcanoes may help to understand the causes of seismicity and contribute to forecast. The volcanic island of Ischia (Italy) shows decades‐long subsidence of its surface up to 1.2 cm/yr and experienced several destructive earthquakes in the last centuries. We use a multidisciplinary approach of mechanical and thermal simulations to understand the active processes and, in turn, to give insights on the causes of such seismicity. We find that the intense degassing of a magmatic body at 2 km depth drives the island‐scale subsidence and causes the observed recurrent seismicity. Our simulations show that degassing will continue for hundreds/thousands years. These results highlight that if seismicity is caused by recognizable magmatic processes, such as degassing, the capacity to forecast earthquakes at volcanoes may be significantly enhanced.
Key Points
About 30 years of leveling data show constant rate subsidence of the resurgent block at Ischia (Italy)
Mechanical and thermo‐petrological simulations indicate magmatic degassing as main cause of the subsidence of the resurgent block
Seismicity marks an acceleration of decades‐long subsidence, driven by degassing that will continue for hundreds/thousands years
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In this paper, empirical fragility curves for reinforced concrete buildings are derived, based on post-earthquake damage data collected in the aftermath of earthquakes occurred in Italy in the period ...1976–2012. These data, made available through an online platform called Da.D.O., provide information on building position, building characteristics and damage detected on different structural components. A critical review of this huge amount of data is carried out to guarantee the consistency among all the considered databases. Then, an in-depth analysis of the degree of completeness of the survey campaign is made, aiming at the identification of the Municipalities subjected to a partial survey campaign, which are discarded from fragility analysis. At the end of this stage, only the Irpinia 1980 and L’Aquila 2009 databases are considered for further elaborations, as fully complying with these criteria. The resulting database is then integrated with non-inspected buildings sited in less affected areas (assumed undamaged), to account for the negative evidence of damage. The PGA evaluated from the shakemaps of the Italian National Institute of Geophysics and Volcanology (INGV) and a metric based on six damage levels according to EMS-98 are used for fragility analysis. The damage levels are obtained from observed damage collected during post-earthquake inspections through existing conversion rules, considering damage to vertical structures and infills/partitions. The maximum damage level observed on vertical structures and infills/partitions is then associated to the whole building. Fragility curves for two vulnerability classes, C2 and D, further subdivided into three classes of building height, are obtained from those derived for specific structural typologies (identified based on building height and type of design), using their frequency of occurrence at national level as weights.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Geodetic observations at Campi Flegrei caldera were initiated in 1905. Historical observations and the few measurements made before 1970 suggested a deflationary trend. Since 1969, the ground started ...to inflate during two major uplift episodes in 1969–72 and 1982–1985. We collected and reanalyzed all available punctual observations of vertical ground displacement taken in the period 1905–2009 with special attention to the period before 1969, to reconstruct in greater detail the deformation history of the caldera. We make use of the many photographs of the sea level in a roman ruin (the Serapeum Market) taken during the period between 1905 and 1969 to infer with more accuracy its relative height with respect to the sea level. We identify a previously disregarded major episode of ground uplift occurred between 1950 and 1952 with a maximum uplift of about 73
cm. This finding suggests that Campi Flegrei is currently experiencing a prolonged period of unrest longer than previously thought. The higher seismicity associated with the later episodes of unrest suggests that the volcano has approached an instability threshold, which may eventually result in a volcanic eruption.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Recent devastating earthquakes worldwide pointed out the importance of seismic detailing and their influence on the observed damage and subsequent repairability of reinforced concrete buildings. ...Several studies and post-earthquake observations remarked the role of beam–column joints (BCJs) on the global building response and the effectiveness of transverse reinforcement in increasing the joint shear strength and the ultimate deformation. Although number of experimental and theoretical studies focused on the seismic response of BCJs, their mechanical behaviour is still a discussed topic. This resulted in number of design approaches available in worldwide code or standards that lead to different quantity of joint stirrups. This study focuses on the response of BCJs of a 10-story prototype building designed according to Japanese standards and tested in 2015 on the E-Defense shaking table. First the damage assessment at global (building) and local (joint) level is performed at increasing intensities and considering the building in the base slip and base fixed configurations. A refined numerical model is then developed and validated against global and local experimental results. Then, the joint stirrups are re-designed according to different international standards (ACI, EC8, NZS) and different numerical models are developed. The numerical results are then compared in terms of interstorey drift demand and joint shear strain. Finally, a comparison in terms of expected damage varying the design approach of joint stirrups is proposed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We have analyzed a multiparametric data set of seismological, geodetic and geochemical data recorded at Campi Flegrei caldera since 1982. We focus here on the period 1989–2010 that followed the last ...bradyseismic crisis of 1982–1984. Since then, there have been at least five repeated minor episodes of ground uplift accompanied by seismicity. We have reanalyzed old paper and digital seismic data sets dating back to 1982. The paper recordings show evidence of long‐period events in January 1982 and March 1989, and we have digitized some of these significant waveforms. Furthermore, the revision of digital seismograms dating back to 1994 shows a significant swarm of long‐period events in August 1994. Volcano‐tectonic and long‐period events hypocenters have been relocated in a three‐dimensional velocity model. Statistical analysis of volcano‐tectonic seismicity shows many similarities and few differences between 1982–1984 and the following period 1989–2010. Long‐period waveforms have been analyzed using spectral analysis, which shows a grouping into three macrofamilies. Similarities in the seismic signature of episodes of minor uplift suggest that they originate from the injection of fluids into the deep part of a geothermal reservoir (about 2.5 km depth) and in its transfer toward a shallower part (about 0.75 km depth). Most of the observed geophysical signals are related to this second phase. The evidence consists of spatial and temporal connections between the ground deformation, long‐period and volcano‐tectonic seismicity and changes in the geochemical parameters of fumaroles. In this study we focused our analysis on two uplift episodes observed in 2000 and 2006. The joint inversion of Differential Synthetic Aperture Radar (DInSAR) and tiltmeter data show that during these periods the ground deformation was generated by at least two distinct sources located at different depths, with the shallower activated in the later stages of the uplift episodes. Our interpretation of the recent dynamics of Campi Flegrei is that the deep part of the geothermal reservoir inflates in response to mass and heat input from a magmatic source. When the pressure exceeds a threshold, fluids starts to migrate into the shallower part. During this transfer, long‐period sources are activated in response to the fluid motion. The gradual diffusion of fluids in the surrounding rocks lowers the resistance of a pervasive fracture system generating shallow microseismicity. Finally, fluids reach the surface, which gives a distinct geochemical signature to the overlying fumaroles.
Key Points
Campi Flegrei geothermal system is composed of at least two parts
Fluid flow in the geothermal system is the main source of seismicity
Geochemical and geophysical signals correlate in a common framework
The island of Ischia, located at the northwestern end of the Gulf of Napoli (Italy), is a volcanic area that is historically active (the Arso eruption, in 1302 and the Casamicciola earthquake, in ...1883) and has diffuse hydrothermal phenomena. We present in this work a study of the surface deformation occurring in the island, which is based on applying the Differential Synthetic Aperture Radar Interferometry (DInSAR) algorithm referred to as Small BAseline Subset (SBAS) technique. This study is focused on the 1992–2003 time interval and SAR data acquired by the European Remote Sensing (ERS) satellites from ascending and descending orbits have been used, thus allowing us to discriminate the vertical and east–west components of the displacements. A validation of the DInSAR results has been carried out first by comparing the vertical deformations estimated from the SAR data with those measured from the spirit leveling network that is present in the area. In particular, we computed the difference between the mean vertical deformation velocities estimated from the SAR and the corresponding geodetic measurements along three main leveling lines; the maximum value of the root mean square difference is of about 1 mm/yr. The final discussion is dedicated to the interpretation of the detected displacements, benefiting from the overall information extracted from the ascending and descending DInSAR measurements. In particular, DInSAR data relative to the vertical deformation component show that the present-day subsidence of Ischia mainly develops in areas characterized by active landsliding and along faults; moreover, the deflation of the island, which is recorded by the horizontal displacement component, is probably related to the de-pressurization of the hydrothermal system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Phlegrean Fields is an active and densely populated caldera near Naples (Italy). Two major unrest episodes characterized its recent history, each leading to remarkable ground uplift and followed by ...slow subsidence. Fumaroles near the caldera centre underwent important chemical changes during these volcanic crises. Based on published data we show that a correlation exits between ground displacement and gas composition. Numerical modelling of hydrothermal circulation shows that periods of enhanced fluid injection at the base of the hydrothermal system, are consistent with the observed chemical variations. The model predicts an average increase in pore pressure and temperature within the system, suggesting potential effects on ground deformation. Literature data and simulation results show that periods of intense magmatic degassing could explain most of the features characterizing recent bradyseismic crises and should be considered a potential trigger for the unrest at Phlegrean Fields, as well as at other calderas in the world.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In the aftermath of the M
w
6.0 August 24, 2016 Central Italy earthquake, the authors carried out a reconnaissance survey in the municipality of Amatrice and gathered extensive photographic evidence ...of damage, with emphasis on 37 reinforced concrete buildings located outside the historical centre. Damage distribution is generally represented by widespread cracking and/or collapse of the masonry infill panels at the lower buildings’ stories. Moreover, damage was observed in the columns due to the interaction with masonry infill panels. Starting from the collected information, POST—a mechanics-based damage prediction model—was applied in order to compare predicted damage distribution and damage observed during the field reconnaissance. The comparison shows an overall good agreement between the results of the POST method and the observed damage with a slightly conservative tendency by POST.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The multidisciplinary field of tissue engineering and regenerative medicine can benefit from the potential of additive manufacturing as a fabrication technique that can realize custom medical ...devices. This is particularly true when referred to the macroscopic dimensions of the resulting scaffold, but focussing on the microstructure that should be realized to offer a suitable environment to the seeded cells, possible drawbacks can be highlighted. In this regard, the present study shows the design and validation of a custom-made set-up capable to deliver thin polymeric strands, below 100 µm diameter, to be used for building up scaffolds for tissue engineering applications. The aim of this work was to develop a specific experimental set-up capable of producing fine polymeric structures by means of a computer-controlled polymer deposition. As manufacturing method a variation of Pressure Assisted Microsyringe was chosen, namely the wet-spinning microsyringe deposition, driven by positive displacement as a trade-off between implementation complexity and extrusion speed control. For this purpose the project started with the design stage to select the proper hardware, especially for micro-positioning system’s accuracy, then followed by a software development step to carefully control the setup. Experimental verification was carried out by depositing repeatable polymer filaments of poly(ε-caprolactone), widely used for tissue engineering applications. In order to preliminarily evaluate the feasibility of the desired outcome, a computational fluid dynamics analysis was carried out simulating a perfusion bioreactor operating at three different conditions. The results, either experimental and numerical, showed the potential of this combined study (i) to carefully select the most relevant processing parameters for collecting suitable strands and (ii) to predict the related response when assembled to form a 3D scaffold in terms of local fluid dynamics
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The genus Salvia includes more than 900 species spread out all over the world. Thirty-one species and cultivars preliminary selected for their morphological, phenological and agronomical ...characteristics were evaluated for pot plant production in Mediterranean climate conditions. Propagation performances by seed or by cutting were tested. Plants were grown in 1.3- or 3.2 L pots during most part of spring and for all the summer period. Three kind of final products were considered, depending on features of the different species: flowering plants, foliage plants, aromatic plants. Nearly all the species showed good propagation results, with a germination or rooting percentage higher than 90% in most cases. Ten flowering species or cultivars (S. blepharophylla, S. coccinea ‘Lady in Red’ and ‘Forest Fire’, S. greggii ‘Alba’ and ‘Peach’, S. microphylla ‘Trenance’, S. roemeriana, S. sinaloensis, S. ×jamensis ‘La Luna’ and ‘La Siesta’), one foliage species (Salvia greggii ‘Caramba’) and four aromatic ones (S. dolomitica, S. dorisiana, S. elegans, S. somalensis) showed a good plant height-width ratio (0.9 to 1.4) and high branching, together with a good foliage compactness. S. aethiopis, S. argentea and S. lyrata ‘Purple Volcano’ showed a height-width ratio of 0.2-0.3 due to their typical aspect in the rosette stage and were considered interesting new products for ornamental foliage. The number of days to production (included propagation phase) ranged from 88.8 (S. elegans) to 151.5 days (S. greggii ‘Peach’): that shows the possibility of obtaining even flowering plants in a short cultivation cycle and confirms the usual high growth rate of Salvia species. The eighteen species selected showed also uniform growth; on plants in anthesis, flowers were abundant and well distributed on the foliage.
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