THE DEEP STRUCTURE OF THE L'AQUILA BASIN INVESTIGATED USING ARRAY MEASUREMENTS

We present velocity profiles obtained through surface-wave methods in the historical city of L’Aquila (Italy). The city suffered severe damage (VIII-IX EMS intensity) during the April 6th 2009 Mw 6.3 earthquake. The area is characterized by the deep (up to 300-400 meters) basin of the Aterno river valley filled by lacustrine sediments over limestone bedrock. In downtown L'Aquila an outcropping unit basically composed of stiff conglomerates (Breccia) is over-imposed to ancient lacustrine sediments with a possible velocity inversion at a depth ranging from few tens up to one hundred meters. We deployed five 2-D arrays of seismic stations and 1-D array of vertical geophones in the city center. The 2-D arrays recorded ambient noise, whereas the 1-D array recorded signals produced by active sources. Surface-wave dispersion and spatial autocorrelation curves, calculated using array methods, were inverted through a neighborhood algorithm jointly with the microtremor HVNSR ellipticity. We obtain shear-wave velocity profiles (Vs) representative of the southern and northern sector of downtown L'Aquila. The resulting Vs profiles are used to compare the 1-D transfer functions to aftershock data results. We apply a convolution approach evaluating synthetic time-histories in sites where surface stratigraphy is known and comparing them to recorded strong-motion data

Evidences for strong directional resonances in intensely deformed zones of the Pernicana fault, Mount Etna, Italy

In this paper we investigate ground motion properties in the western part of the Pernicana fault. This is the major fault of Mount Etna and drives the dynamic evolution of the area. In a previous work, Rigano et al. (2008) showed that a significant horizontal polarization characterizes ground motion in fault zones of Mount Etna, both during earthquakes and ambient vibrations. We have performed denser microtremor measurements in the NE rift segment and in intensely deformed zones of the Pernicana fault at Piano Pernicana. This study includes mapping of azimuth-dependent horizontal-to-vertical spectral ratios along and across the fault, frequency–wave number techniques applied to array data to investigate the nature of ambient vibrations, and polarization analysis through the conventional covariance matrix method. Our results indicate that microtremors are likely composed of volcanic tremor. Spectral ratios show strong directional resonances of horizontal components around 1 Hz when measurements enter the most damaged part of the fault zone. Their polarization directions show an abrupt change, by 20° to 40°, at close measurements between the northern and southern part of the fault zone. Recordings of local earthquakes at one site in the fault zone confirm the occurrence of polarization with the same angle found using volcanic tremor. We have also found that the directional effect is not time-dependent, at least at a seasonal scale. This observation and the similar behavior of volcanic tremors and earthquake-induced ground motions suggest that horizontal polarization is the effect of local fault properties. However, the 1-Hz resonant frequency cannot be reproduced using the 1-D vertically varying model inferred from the array data analysis, suggesting a role of lateral variations of the fault zone. Although the actual cause of polarization is unknown, a role of stress-induced anisotropy and microfracture orientation in the near-surface lavas of the Pernicana fault can be hypothesized consistently with the sharp rotation of the polarization angle within the damaged fault zone

Assessment of ground-motion amplification in the Fucino Basin (Central Italy) through seismic data

The Fucino basin (Central Italy) is one of the largest intermountain alluvial plain in the Appennines range. It has a tectonic origin related to the presence of important systems of faults located in its northern and eastern edges. Some of these faults are still active and capable of generating strong seismic events as the January 13th 1915 Ms 7.0 Avezzano earthquake (about 30000 casualties). Site effects related to the soft soils filling the basin can be very important also taking into account the presence of historical villages located at the edges of the basin and new settlements developed in the area. In this paper we show the preliminary results of a seismic network installed in the Fucino area in order to collect information about site amplification effects and geometry of the basin. A lake occupied the Fucino basin for many thousands of years and it was completely drained at the end of the 19th century. We analyze ambient seismic vibrations and recordings of about 150 local earthquakes mainly related to the seismic sequence of the April 6th 2009 Mw 6.3 L’Aquila event. Moreover the strongest events of L’Aquila sequence were analyzed at the three strong-motion permanent stations operating in the area. Using standard spectral techniques we investigate the variation of resonance frequencies within the basin. The ground motion recorded in the Fucino plain is mainly characterized by strong energy at low-frequencies (f < 1 Hz) affecting both horizontal and vertical components. This is particularly evident for stations deployed in correspondence of very thick deposits of sedimentary filling, where a significant increase of ground-motion amplitude and duration is caused by locally generated surface waves. The amplification at low-frequencies (< 1 Hz) on the horizontal components can reach up a factor of 10 in comparison to nearby stiff sites. However, we found evidences of seismic amplification phenomena also for stiff sites surrounding the basin, including stations of the Italian strong motion network. The independent geological information, the shallow shear-velocity profiles available for the basin can be combined with resonance frequencies of the sites for deriving representative geological sections to be used as base for future numerical 2D-3D modeling of the seismic wave propagation in the basin. Seismic modeling can be important to reduce the seismic hazard in the area

Assessment of ground-motion amplification in the Fucino Basin (Central Italy) through seismic data

The Fucino basin (Central Italy) is one of the largest intermountain alluvial plain in the Appennines range. It has a tectonic origin related to the presence of important systems of faults located in its northern and eastern edges. Some of these faults are still active and capable of generating strong seismic events as the January 13th 1915 Ms 7.0 Avezzano earthquake (about 30000 casualties). Site effects related to the soft soils filling the basin can be very important also taking into account the presence of historical villages located at the edges of the basin and new settlements developed in the area. In this paper we show the preliminary results of a seismic network installed in the Fucino area in order to collect information about site amplification effects and geometry of the basin. A lake occupied the Fucino basin for many thousands of years and it was completely drained at the end of the 19th century. We analyze ambient seismic vibrations and recordings of about 150 local earthquakes mainly related to the seismic sequence of the April 6th 2009 Mw 6.3 L’Aquila event. Moreover the strongest events of L’Aquila sequence were analyzed at the three strong-motion permanent stations operating in the area. Using standard spectral techniques we investigate the variation of resonance frequencies within the basin. The ground motion recorded in the Fucino plain is mainly characterized by strong energy at low-frequencies (f < 1 Hz) affecting both horizontal and vertical components. This is particularly evident for stations deployed in correspondence of very thick deposits of sedimentary filling, where a significant increase of ground-motion amplitude and duration is caused by locally generated surface waves. The amplification at low-frequencies (< 1 Hz) on the horizontal components can reach up a factor of 10 in comparison to nearby stiff sites. However, we found evidences of seismic amplification phenomena also for stiff sites surrounding the basin, including stations of the Italian strong motion network. The independent geological information, the shallow shear-velocity profiles available for the basin can be combined with resonance frequencies of the sites for deriving representative geological sections to be used as base for future numerical 2D-3D modeling of the seismic wave propagation in the basin. Seismic modeling can be important to reduce the seismic hazard in the area

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

Synchronous versus asynchronous modeling of gene regulatory networks

Motivation: In silico modeling of gene regulatory networks has gained some momentum recently due to increased interest in analyzing the dynamics of biological systems. This has been further facilitated by the increasing availability of experimental data on gene–gene, protein–protein and gene–protein interactions. The two dynamical properties that are often experimentally testable are perturbations and stable steady states. Although a lot of work has been done on the identification of steady states, not much work has been reported on in silico modeling of cellular differentiation processes

Seismic response and wavefield characterization using a very dense 2D seismic array on an active landslide (Cavola, Italy)

A dense 2D array (95 broad-band stations) was installed in a grid-like configuration over a 130x56 m area on the active landslide of Cavola in northern Apennines. Outcropping rocks consist of Monte Piano (fractured flysch and clayey melanges) and Ranzano (muddy and sandstone turbidite) formations of Eocene-Oligocene age. These units are covered by a 4-km long landslide with maximum thickness more than 60 m. In historical times there are three instances of activity triggered by meteorological events, in 1938, 1940, and 1960. The latter event was the most damaging, involving an area of 1.3 km2 and partial destruction of the Cavola village. Recent SAR interferometric analyses coupled to inclinometer data for the supposedly dormant period 1995-2001 show movements between 10-15 mm/yr affecting mainly areas close to the landslide side-scarps and to a new industrial district with active sliding surface at a depth of 10-15 m. The landslide structure beneath the array was reconstructed by means of active and passive seismic surveys, in-situ velocity measurements and geoelectrical tomography obtaining clay thickness ranging from 0 to 45 m and with average shear-velocity of 350 m/s. The inferred model is used for numerical 2D simulation of earthquake ground motion for different incidence angle and type of waves. The data from 11 of more than 100 local earthquakes recorded at the array have been used for the comparison with model results. The long data records (3 months of continuous recording) allow investigation of properties of ambient noise in terms of temporal stability and wavefield composition. We find that local industrial sources affect the H/V spectral ratios and their interpretation in terms of resonant frequencies. Analysis of noise polarization is also performed, revealing different patterns depending on the nature of the noise source

Extracellular vesicles shed by melanoma cells contain a modified form of H1.0 linker histone and H1.0 mRNA-binding proteins

Extracellular vesicles (EVs) are now recognized as a fundamental way for cell-to-cell horizontal transfer of properties, in both physiological and pathological conditions. Most of EV-mediated cross-talk among cells depend on the exchange of proteins, and nucleic acids, among which mRNAs, and non-coding RNAs such as different species of miRNAs. Cancer cells, in particular, use EVs to discard molecules which could be dangerous to them (for example differentiation-inducing proteins such as histone H1.0, or antitumor drugs), to transfer molecules which, after entering the surrounding cells, are able to transform their phenotype, and even to secrete factors, which allow escaping from immune surveillance. Herein we report that melanoma cells not only secrete EVs which contain a modified form of H1.0 histone, but also transport the corresponding mRNA. Given the already known role in tumorigenesis of some RNA binding proteins (RBPs), we also searched for proteins of this class in EVs. This study revealed the presence in A375 melanoma cells of at least three RBPs, with apparent MW of about 65, 45 and 38 kDa, which are able to bind H1.0 mRNA. Moreover, we purified one of these proteins, which by MALDI-TOF mass spectrometry was identified as the already known transcription factor MYEF2