219 research outputs found
Struttura crostale e subcrostale della penisola italiana dalla interpretazione congiunta di immagini tomografiche e profile DSS
Questo studio rappresenta la conclusione di una serie di analisi precedentemente proposte e volte alla migliore comprensione della struttura profonda della penisola italiana. Tale serie, iniziata con il confronto tra la sismicità crostale e le interpretazioni dei profili DSS (Cassinis e Solarino, 2004; Cassinis e Solarino, 2006), si era successivamente estesa alla struttura litosferica (Solarino e Cassinis, 2005; Solarino e Cassinis, 2007). In ambedue le occasioni lo studio era stato condotto avendo cura di utilizzare le più recenti elaborazioni dei profili e selezionando gli ipocentri con criteri molto restrittivi.
Nello spirito dei precedenti lavori, anche in questo caso si è eseguita una analisi congiunta di dati ottenuti con diverse tecniche sovrapponendo alle interpretazioni già esistenti le informazioni ricavate da un recente studio tomografico (Scafidi et al., 2008) effettuato con la tecnica della inversione di terremoti locali (Thurber, 1983)
An automatically generated high-resolution earthquake catalogue for the 2016–2017 Central Italy seismic sequence, including P and S phase arrival times
The 2016–2017 central Italy earthquake sequence began with the first main shock near the town of Amatrice on August 24 (Mw 6.0), and was followed by two subsequent large events near Visso on October 26 (Mw 5.9) and Norcia on October 30 (Mw 6.5), plus a cluster of four events with Mw > 5.0 within few hours on 18 January 2017. The affected area had been monitored before the sequence started by the permanent Italian National Seismic Network (RSNC), and was enhanced during the sequence by temporary stations deployed by the National Institute of Geophysics and Volcanology and the British Geological Survey. By the middle of September, there was a dense network of 155 stations, with a mean separation in the epicentral area of 6–10 km, comparable to the most likely earthquake depth range in the region. This network configuration was kept stable for an entire year, producing 2.5 TB of continuous waveform recordings.
Here we describe how this data was used to develop a large and comprehensive earthquake catalogue using the Complete Automatic Seismic Processor (CASP) procedure. This procedure detected more than 450 000 events in the year following the first main shock, and determined their phase arrival times through an advanced picker engine (RSNI-Picker2), producing a set of about 7 million P- and 10 million S-wave arrival times. These were then used to locate the events using a non-linear location (NLL) algorithm, a 1-D velocity model calibrated for the area, and station corrections and then to compute their local magnitudes (ML). The procedure was validated by comparison of the derived data for phase picks and earthquake parameters with a handpicked reference catalogue (hereinafter referred to as ‘RefCat’). The automated procedure takes less than 12 hr on an Intel Core-i7 workstation to analyse the primary waveform data and to detect and locate 3000 events on the most seismically active day of the sequence. This proves the concept that the CASP algorithm can provide effectively real-time data for input into daily operational earthquake forecasts,
The results show that there have been significant improvements compared to RefCat obtained in the same period using manual phase picks. The number of detected and located events is higher (from 84 401 to 450 000), the magnitude of completeness is lower (from ML 1.4 to 0.6), and also the number of phase picks is greater with an average number of 72 picked arrival for a ML = 1.4 compared with 30 phases for RefCat using manual phase picking. These propagate into formal uncertainties of ±0.9 km in epicentral location and ±1.5 km in depth for the enhanced catalogue for the vast majority of the events. Together, these provide a significant improvement in the resolution of fine structures such as local planar structures and clusters, in particular the identification of shallow events occurring in parts of the crust previously thought to be inactive. The lower completeness magnitude provides a rich data set for development and testing of analysis techniques of seismic sequences evolution, including real-time, operational monitoring of b-value, time-dependent hazard evaluation and aftershock forecasting
Evaluation of liquefaction triggering potential in Italy: a seismic-hazard-based approach
In the present study, we analyze ground-motion hazard
maps and hazard disaggregation in order to define areas in Italy where
liquefaction triggering due to seismic activity can not be excluded. To this
end, we refer to the triggering criteria (not to be confused with
liquefaction susceptibility criteria, which essentially take into account
soil type and depth to groundwater) proposed by the Italian Guidelines for
Seismic Microzonation, which are described in the main body of the
paper. However, the study can be replicated in other countries that
adopt different criteria. The final goal is the definition of a screening
map for all of Italy that classifies sites in terms of liquefaction
triggering potential according to their seismic hazard level. The map, which
is referred to with the Italian acronym MILQ – Mappa del potenziale d'Innesco
della LiQuefazione (i.e., map of liquefaction triggering potential), and the
associated data are freely accessible at the following web address:
https://distav.unige.it/rsni/milq.php (last access: 28 April 2023). Our results can be useful to guide
land-use planners in deciding whether liquefaction is a hazard that needs to
be considered within the planning processes or not. Furthermore, they can
serve as a guide for recommending geological and geotechnical investigations
aimed at the evaluation of liquefaction hazards or, conversely, rule out
further studies with consequent savings in efforts and money.</p
Cigarette smoke increases BLT2 receptor functions in bronchial epithelial cells: in vitro and ex vivo evidence
Leukotriene B4 (LTB4) is a neutrophil chemotactic molecule with important
involvement in the inflammatory responses of chronic obstructive
pulmonary disease (COPD). Airway epithelium is emerging as a regulator
of innate immune responses to a variety of insults including cigarette
smoke, the major risk factor for COPD. In this study we have explored
whether cigarette smoke extracts (CSE) or soluble mediators present in
distal lung fluid samples (mini-bronchoalveolar lavages) from smokers
alter the expression of the LTB4 receptor 2 (BLT2) and peroxisome proliferator-
activated receptor-a (PPAR-a) in bronchial epithelial cells. We also
evaluated the effects of CSE on the expression of intercellular adhesion
molecule 1 (ICAM-1) and on the binding of signal transducer and activator
of transcription 1 (STAT-1) to ICAM-1 promoter as well as the
adhesiveness of neutrophils to bronchial epithelial cells. CSE and minibronchoalveolar
lavages from smokers increased BLT2 and ICAM-1
expression as well as the adhesiveness of neutrophils to bronchial epithelial
cells and decreased PPAR-a expression. CSE induced the activation of
STAT-1 and its binding to ICAM-1 promoter. These findings suggest that,
in bronchial epithelial cells, CSE promote a prevalent induction of
pro-inflammatory BLT2 receptors and activate mechanisms leading to
increased neutrophil adhesion, a mechanism that contributes to airway
neutrophilia and to tissue damage
Seismotectonic analysis of a complex fault system in Italy: the "Garfagnana-North" (Northern Tuscany) line
We present the results obtained combining different techniques to determine the seismotectonic character of the Garfagnana region (northern Tuscany). There, the existence of a rather complex fault system is acknowledged and somewhat mapped, but apart from the geological evidences, very little is known about its extension with depth and the regime.
The seismic potential of the system is also well known. The area was characterized, in the past, by destructive earthquakes; in particular a major event (Ms=6.4) struck the Lunigiana-Garfagnana area in September 1920, but many others have been reported. Therefore, the seismicity is under constant monitoring by the national seismic network (RSNC – National Central Seismic Network) and a pool of local stations, belonging to a regional network (RSLG – Regional Seimic network of Lunigiana and Garfagnana). These additional stations account for the lower magnitude seismicity.
Such a concentration of seismic stations, and the consequent availability of several seismograms, makes likely to record and localize earthquakes down to a very low magnitude threshold (inferior to Ml = 2.0) with extremely narrow hypocentral parameter errors .
Making use of the resulting databases, several analyses were conducted to determine the shape, size, extension with depth of the fault and the associated seismicity. The methodology consists in seismic tomography (1D and 3D velocity models), precise location algorithms NonLinLoc and HypoDD (very constrained and reliable locations) and computation of focal mechanisms (fault orientation and source), all combined with the constraints provided by the geology.
The main findings of the study are that the concentration of the recent seismic activity is close to the likely location of the most relevant historical events. In particular the earthquakes are distributed along a plane in the range 0 – 20 km depth dipping 30° NE. All focal mechanisms show a transtensive character
Brain energy metabolism: A roadmap for future research
Although we have learned much about how the brain fuels its functions over the last decades, there remains much still to discover in an organ that is so complex. This article lays out major gaps in our knowledge of interrelationships between brain metabolism and brain function, including biochemical, cellular, and subcellular aspects of functional metabolism and its imaging in adult brain, as well as during development, aging, and disease. The focus is on unknowns in metabolism of major brain substrates and associated transporters, the roles of insulin and of lipid droplets, the emerging role of metabolism in microglia, mysteries about the major brain cofactor and signaling molecule NAD+, as well as unsolved problems underlying brain metabolism in pathologies such as traumatic brain injury, epilepsy, and metabolic downregulation during hibernation. It describes our current level of understanding of these facets of brain energy metabolism as well as a roadmap for future research
A dense micro-electromechanical system (MEMS)-based seismic network in populated areas: rapid estimation of exposure maps in Trentino (NE Italy)
The micro-electromechanical system (MEMS)-based seismic network of Trentino (NE Italy) consists of 73 low-cost accelerometers installed close to inhabited areas. These sensors have a suitable sensitivity to detect moderate-to-strong earthquakes but are able to record even weaker seismicity. The densely distributed peak ground acceleration values recorded by MEMS and other types of stations are integrated within the existing seismic monitoring procedure in order to automatically obtain a complete set of strong motion parameters a few minutes after the origin time. The exposure of the resident population and critical buildings is estimated by quantifying the different levels of shaking, which is expressed according to the Mercalli–Cancani–Sieberg intensity scale. These types of results, summarized in synthetic portable document format (PDF), can be useful for civil protection purposes to evaluate the state of emergency after a strong earthquake in a timely manner and to choose how and where to activate first aid measures and targeted structural monitoring.</p
Il terremoto del 21 giugno 2013 in Lunigiana. Le attività del coordinamento Sismiko
Il 21 giugno 2013 alle ore 10.33 UTC è stato registrato dalla Rete Sismica Nazionale (RSN) [Amato e
Mele, 2008; Delladio, 2011] dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) un terremoto di
magnitudo (ML) 5.2 nel distretto sismico1 denominato “Alpi Apuane” tra i comuni di Minucciano in
provincia di Lucca e Fivizzano e Casola in provincia di Massa e Carrara, zona conosciuta come “Lunigiana”.
L’evento sismico, localizzato dai sismologi in turno presso la sala di sorveglianza sismica di Roma [Basili,
2011] con coordinate 44.153°N e 10.135° E e una profondità di circa 5 km è stato ben risentito in tutta la
penisola centro-settentrionale ed è stato seguito in poche ore da numerosi eventi anche di ML ≥ 3.0 (16 nelle
prime 72 ore). Storicamente l’area oggetto della sequenza sismica è stata interessata da numerosi terremoti di
magnitudo superiore a 5.0 il più grande dei quali quello avvenuto nel 1920 nella zona della Garfagnana
(fonte dati: Catalogo Parametrico dei Terremoti Italiani - CPTI11 [Rovida et al., 2011]), ad una distanza di
circa 12 km dal mainshock odierno, interessata anch’essa da una piccola sequenza sismica a gennaio del
2013.
In considerazione dell’entità dell’evento e seguendo le procedure definite per le situazioni di
emergenza internamente all’INGV anche in accordo con l’Allegato A2 della Convenzione vigente 2012-
20203 fra l’ente e il Dipartimento di Protezione Civile (DPC), è stata attivata la Rete Sismica Mobile della
sede INGV di Roma (Re.Mo. [Moretti et al., 2010]). Nell’arco di tempo di poco più un’ora dall’accadimento
del mainshock è stata disposta l’installazione di una rete sismica temporanea costituita da sei stazioni a
integrazione delle reti sismiche permanenti già presenti in area epicentrale (RSN e Regional Seismic network
of North-Western Italy – RSNI [Ferretti et al., 2008; 2010; Eva et al., 2010; Pasta et al., 2011]).
Nel contempo sono stati consultati tramite e-mail i referenti delle unità di rete sismica mobile delle
altre sedi INGV che nell’ambito del coordinamento “Sismiko” [Moretti et al., 2012] negli ultimi due anni
hanno dato la propria disponibilità, in termini di personale e strumentazione, ad intervenire in caso di
emergenza sismica; sono stati inoltre contattati i colleghi del Dipartimento di Scienze della Terra,
dell’Ambiente e della Vita, dell’Università degli Studi di Genova (DISTAV) i più vicini all’area epicentrale
e gestori della RSNI che hanno comunicato loro stessi l’intenzione di installare due stazioni temporanee, una
in real-time e una in configurazione stand-alone.
In questo lavoro viene descritta l’attività compiuta dalla Rete Sismica Mobile INGV, la tempistica
dell’intervento effettuato in sinergia con i colleghi dell’Università di Genova, i dettagli circa l'installazione e
la gestione delle stazioni sismiche temporanee nel primo mese di attività e una valutazione del dataset
acquisito
The Grosmarin experiment
The GROSMARIN
(which stands for GrandROSMARIN) cruise is proposed by UMR Géosciences Azur (with fellow
french and italian research groups). Its goals are to better characterize active structures along this zone and to assess the resulting seismic hazard in a sort of continuation with respect to the MALISAR
experiment, which has already surveyed some active structures through shallow observations.
The GROSMARIN cruise is in fact the necessary counterpart to characterize them at depth
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