Characterization of the breccia deposits in downtown L’Aquila (Central Italy) through multichannel analysis of surface waves

On April 6th 2009 an Mw 6.3 earthquake hit the historical city of L’Aquila (Central Italy) causing about 300 causalities, more than 39000 homeless and strong damage in the city and in the surrounding villages. L’Aquila downtown suffered Mercalli-Cancani-Sieberg (MCS; Sieberg 1930) intensity > VIII. Heavy damage and collapses were concentrated in the unreinforced masonry buildings including historical churches. Starting from June 2009, the Italian Civil Defense Department promoted a microzoning study of the epicentral area, aimed at identifying, at a detailed scale, areas were local seismic amplification could occur due to the characteristics of surface geology. L’Aquila is founded on a terrace that slopes down moving in the southwest direction, and raises about 50 meters above the Aterno river bed. The terrace is formed by alluvial Quaternary breccias consisting of limestone clasts in a marly matrix. In the northern part of the city the terrace is in contact with outcropping limestone, while moving toward south, breccias are over imposed to lacustrine sediments formed mainly of silty and sandy layers and minor gravel beds. As found by boreholes, the thickness of the breccias formation ranges from tenths of meters at north to just few meters at south. The uppermost weathered part of breccias outcrops at south and is indicated as “limi rossi”. The presence of breccias and “limi rossi” in the northern and southern part of the city respectively, is well identified by collected geotechnical data. Shear wave velocity (Vs) are quite high in the northern sector and can reach values of about 1000 m/s, whereas in the southernmost part the Vs of “limi rossi” drops down to 300-400 m/s. The microzoning studies at L’Aquila evidenced the presence of low-frequency (about 0.6 Hz) amplification diffused in the historical center with high amplification factors in the southern area of the city were “limi rossi” outcrops. We here present the results of multichannel surface waves analysis (MASW) based on active and passive sources. Active methods consist of 1D linear arrays of 4.5 Hz-vertical geophones using a minigun as source. Passive methods consist of 2D arrays of seismic three-component sensors. In order to investigate the low-frequency amplification, the geometry of 2D arrays was accordingly designed, using 16 seismic stations with maximum aperture of 1 km that recorded many hours of ambient seismic noise. We deployed three 2D arrays, one in the northern part and two in the southern part of the city. The 1D linear array was dedicated to characterize the shallower part of “limi rossi”. With the aim to derive the shear wave velocity profiles, the apparent phase velocity estimated through arrays technique has been inverted through a neighborhood algorithm

Characterization of the breccia deposits in downtown L’Aquila (Central Italy) through multichannel analysis of surface waves

On April 6th 2009 an Mw 6.3 earthquake hit the historical city of L’Aquila (Central Italy) causing about 300 causalities, more than 39000 homeless and strong damage in the city and in the surrounding villages. L’Aquila downtown suffered Mercalli-Cancani-Sieberg (MCS; Sieberg 1930) intensity > VIII. Heavy damage and collapses were concentrated in the unreinforced masonry buildings including historical churches. Starting from June 2009, the Italian Civil Defense Department promoted a microzoning study of the epicentral area, aimed at identifying, at a detailed scale, areas were local seismic amplification could occur due to the characteristics of surface geology. L’Aquila is founded on a terrace that slopes down moving in the southwest direction, and raises about 50 meters above the Aterno river bed. The terrace is formed by alluvial Quaternary breccias consisting of limestone clasts in a marly matrix. In the northern part of the city the terrace is in contact with outcropping limestone, while moving toward south, breccias are over imposed to lacustrine sediments formed mainly of silty and sandy layers and minor gravel beds. As found by boreholes, the thickness of the breccias formation ranges from tenths of meters at north to just few meters at south. The uppermost weathered part of breccias outcrops at south and is indicated as “limi rossi”. The presence of breccias and “limi rossi” in the northern and southern part of the city respectively, is well identified by collected geotechnical data. Shear wave velocity (Vs) are quite high in the northern sector and can reach values of about 1000 m/s, whereas in the southernmost part the Vs of “limi rossi” drops down to 300-400 m/s. The microzoning studies at L’Aquila evidenced the presence of low-frequency (about 0.6 Hz) amplification diffused in the historical center with high amplification factors in the southern area of the city were “limi rossi” outcrops. We here present the results of multichannel surface waves analysis (MASW) based on active and passive sources. Active methods consist of 1D linear arrays of 4.5 Hz-vertical geophones using a minigun as source. Passive methods consist of 2D arrays of seismic three-component sensors. In order to investigate the low-frequency amplification, the geometry of 2D arrays was accordingly designed, using 16 seismic stations with maximum aperture of 1 km that recorded many hours of ambient seismic noise. We deployed three 2D arrays, one in the northern part and two in the southern part of the city. The 1D linear array was dedicated to characterize the shallower part of “limi rossi”. With the aim to derive the shear wave velocity profiles, the apparent phase velocity estimated through arrays technique has been inverted through a neighborhood algorithm

Seismic noise in a geologically complex site (L’Aquila, central Italy) to fine-tune the subsoil model for seismic microzonation mapping

We present the fine scale investigations of seismic noise carried out in a geologically complex site in the Aterno R. Valley (L’Aquila, central Italy). The goals of the study are to point out the efficiency of seismic noise technique in geologically complex site by comparing those data with other geophysical investigations (active seismic techniques, gravimetric survey) and geological data (more than 60 well logs and a detailed fine scale geological mapping), to fine-tune the subsoil model and to locate the geometry of seismic and geological bedrock. The study area is located in the western part of L’Aquila intramontane plain which was struck by the recent April 6 earthquake (Mw: 6.3). L’Aquila intramontane plain is a typical Quaternary basin of central Apennines and it is a halfgraben extending in a WNW-ESE direction, along the Aterno River Valley. The carbonate bedrock is variably displaced by normal faults, with both Apennine (NW-SE) and anti-Apennine (NE-SW) directions, and by a N-dipping back-thrust. The alluvial deposits consist of more or less coarse gravels, sands and silty clays of fluvial and alluvial-fan environments organised in lenticular bodies. The model of subsoil was reconstructed by correlating borehole stratigraphies with data from geophysical tests (down-hole, cross-hole and microtremor measurements). In the study area the presence of a double amplification peak is the main characteristics of HVNSR data. This feature can be related to the presence of two strong impedance contrasts in the deposits filling the Aterno R. Valley. A first shallow contrast, due to the presence of the gravel layer found in the cross hole data, is responsible for the high frequency ( > 10Hz) HVNSR peak, while the deeper contrast between recent sedimentary layers and the limestone, acting as seismic bedrock,k at depth of few tents of meters produces the second peak centered at 3Hz. The inversion of microtremor data, constrained by stratigraphic logs and seismic in-hole tests (down-hole, cross-hole), made it possible to demarcate zones with constant Vs and to reconstruct the depth of the carbonate (or seismic) bedrock; this depth ranged from 0 to 52 m from ground level. The Vs velocities of the alluvial and slope covers range from 300 m/s to 600 m/s. The Vs velocities in the central sector of the valley exceed 400 m/s; this is due to the occurrence of gravely lenses, which reach their maximum thickness in this sector. This study is a good example of how the seismic noise could furnish a useful contribution to fine-tune the subsoil model also in geologically complex sites

Silica Meets Tannic Acid: Designing Green Nanoplatforms for Environment Preservation

Hybrid tannic acid-silica-based porous nanoparticles, TA-SiO2 NPs, have been synthesized under mild conditions in the presence of green and renewable tannic acid biopolymer, a glycoside polymer of gallic acid present in a large part of plants. Tannic acid (TA) was exploited as both a structuring directing agent and green chelating site for heavy metal ions recovery from aqueous solu-tions. Particles morphologies and porosity were easily tuned by varying the TA initial amount. The sample produced with the largest TA amount showed a specific surface area an order of magnitude larger than silica nanoparticles. The adsorption performance was investigated by using TA-5SiO2 NPs as adsorbents for copper (II) ions from an aqueous solution. The effects of the initial Cu2+ ions concentration and the pH values on the adsorption capability were also investigated. The resulting TA-SiO2 NPs exhibited a different adsorption behaviour towards Cu2+, which was demonstrated through different tests. The largest adsorption (i.e., ~50 wt% of the initial Cu2+ amount) was obtained with the more porous nanoplatforms bearing a higher final TA content. The TA-nanoplatforms, stable in pH value around neutral conditions, can be easily produced and their use would well comply with a green strategy to reduce wastewater pollution

Seismic response of L’Aquila (Central Appennines, Italy) from 2D numerical simulation

Experimental and modeling approaches fulfill complementary needs in the assessment of the seismic soil response. Here we present some results from 2D simulation performed for the L’Aquila basin (Central Appennines, Italy). The city of L’Aquila on April 6th, 2009 at 01:32 UTC was struck by a magnitude Mw=6.3 earthquake localized about 2 kilometers west of the city centre at hypocentral depth 9 km. The city of L’Aquila suffered wide spread destructive damage in its historical centre where housing is mainly 2 to 3 storey medieval masonry. Several reinforced concrete buildings built in the late 70s collapsed in the south-west section of the city and also monumental, historical churches were severely damaged. Because of its location, the ground motion recorded in the city is strongly influenced by the source rupture mechanism, nonetheless, local amplification are expected to have influenced the ground shacking. L’Aquila is indeed built over a Quaternary terraced alluvial-lacustrine basin with a rather complex lithology as well as surface topography. The 2D seismic modeling of L’Aquila terrace was already performed by several authors along transversally oriented (NE-SW) geological sections. In this study we present some new results obtained by the use of longitudinal cross sections (NW-SE) in order to better understand the role of lateral geological heterogeneities as derived by recent geological and geophysical data. The simulations have been performed using the impedance-operator-based numerical code. The models of L’Aquila terrace are based on geological and geophysical investigations performed in the framework of the micro-zoning activities of the city following the disastrous April 6th 2009 Mw=6.3 earthquake and in subsequent studies. The depth to the bedrock of the basin is constrained by gravimetric and deep borehole data with an estimated maximum depth of about 300 m. The basin is filled by silt and silty-clay of lacustrine origin topped by a breccia layer (BrA) of gravitational-fluvial origin. BrA does not extend continuously over the terrace and in particular in the southern area of the city it is locally replaced by silt and silty-clay of lacustrine origin with lens of BrA and gravel with silt. Locally, on the top of the terrace lens of less competent red silt were found by the recent deep borehole surveys performed in the micro-zoning activities. We have further constrained our 2D models using the resonance frequencies from noise and earthquake spectral ratios for selected sites. The wave velocities have been inferred by MASW and cross-hole analyses. We have compared the spectral ratios obtained from SH, P-SV and Rayleigh incident waves field in the range 0 -90 to the observed spectral ratios computed using the earthquake aftershocks recorded by the micro-zoning portable network. The modeling results are able to match the resonance frequency obtained by seismological data and to verify the role of the reversal in the velocity-depth profile and the lateral continuity of the top fast layer (BrA)

Periodontitis and Hypertension: Is the Association Causal?

High blood pressure (BP) and periodontitis are two highly prevalent conditions worldwide with a significant impact on cardiovascular disease (CVD) complications. Poor periodontal health is associated with increased prevalence of hypertension and may have an influence on BP control. Risk factors such as older age, male gender, non-Caucasian ethnicity, smoking, overweight/obesity, diabetes, low socioeconomic status, and poor education have been considered the common denominators underpinning this relationship. However, recent evidence indicates that the association between periodontitis and hypertension is independent of common risk factors and may in fact be causal in nature. Low-grade systemic inflammation and redox imbalance, in particular, represent the major underlying mechanisms in this relationship. Neutrophil dysfunction, imbalance in T cell subtypes, oral-gut dysbiosis, hyperexpression of proinflammatory genes, and increased sympathetic outflow are some of the pathogenetic events involved. In addition, novel findings indicate that common genetic bases might shape the immune profile towards this clinical phenotype, offering a rationale for potential therapeutic and prevention strategies of public health interest. This review summarizes recent advances, knowledge gaps and possible future directions in the field

On the cosmological mass function theory

This paper provides, from one side, a review of the theory of the cosmological mass function from a theoretical point of view, starting from the seminal paper of Press & Shechter (1974) to the last developments (Del Popolo & Gambera (1998, 1999), Sheth & Tormen 1999 (ST), Sheth, Mo & Tormen 2001 (ST1), Jenkins et al. 2001 (J01), Shet & Tormen 2002 (ST2), Del Popolo 2002a, Yagi et al. 2004 (YNY)), and from another side some improvements on the multiplicity function models in literature. ...Comment: Astronomy Reports, in prin

Face Mask Use in the Community for Reducing the Spread of COVID-19: A Systematic Review.

Background: Evidence is needed on the effectiveness of wearing face masks in the community to prevent SARS-CoV-2 transmission. Methods: Systematic review and meta-analysis to investigate the efficacy and effectiveness of face mask use in a community setting and to predict the effectiveness of wearing a mask. We searched MEDLINE, EMBASE, SCISEARCH, The Cochrane Library, and pre-prints from inception to 22 April 2020 without restriction by language. We rated the certainty of evidence according to Cochrane and GRADE approach. Findings: Our search identified 35 studies, including three randomized controlled trials (RCTs) (4,017 patients), 10 comparative studies (18,984 patients), 13 predictive models, nine laboratory experimental studies. For reducing infection rates, the estimates of cluster-RCTs were in favor of wearing face masks vs. no mask, but not at statistically significant levels (adjusted OR 0.90, 95% CI 0.78–1.05). Similar findings were reported in observational studies. Mathematical models indicated an important decrease in mortality when the population mask coverage is near-universal, regardless of mask efficacy. In the best-case scenario, when the mask efficacy is at 95%, the R0 can fall to 0.99 from an initial value of 16.90. Levels of mask filtration efficiency were heterogeneous, depending on the materials used (surgical mask: 45–97%). One laboratory study suggested a viral load reduction of 0.25 (95% CI 0.09–0.67) in favor of mask vs. no mask. Interpretation: The findings of this systematic review and meta-analysis support the use of face masks in a community setting. Robust randomized trials on face mask effectiveness are needed to inform evidence-based policies. PROSPERO registration: CRD42020184963