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Olivieri, Marco
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Olivieri, Marco
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marco.olivieri@ingv.it
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44 results
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- PublicationRestrictedEmpirical mode decomposition of long-term polar motion observation(2015)
; ; ; ;Spada, G.; Dip.to di Scienze di Base e Fondamenti, Università di Urbino, Urbino, Italy ;Galassi, G.; Dipartimento di Scienze di Base e Fondamenti, Urbino University “Carlo Bo” ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; We use the Empirical Mode Decomposition (EMD) method to study the decadal variations in polar motion and its long-term trend since year 1900. The existence of the so-called “Markowitz wobble”, a multidecadal fluctuation of the mean pole of rotation whose nature has long been debated since its discovery in 1960, is confirmed. In the EMD approach, the Markowitz wobble naturally arises as an empirical oscillatory term in polar motion, showing significant amplitude variations and a period of approximately 3 decades. The path of the time-averaged, non-cyclic component of polar motion matches the results of previous investigations based on classical spectral methods. However, our analysis also reveals previously unnoticed steep variations (change points) in the rate and the direction of secular polar motion.420 84 - PublicationOpen AccessThe Mediterranean broad band seismographic network(2005-09-11)
; ; ; ; ;Mazza, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Mandiello, A. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Casale, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; ; ; ;Advanced Research Workshop -, - NatoAdvanced Research Workshop -, - NatoThe Mediterrean Network (MedNet) presently comprises 22 operating broadband seismic stations installed and maintained in cooperation with 13 geophysical institutions in Italy and in most of the countries adjacent to Mediterranean Sea. The number of stations may vary as stations are opened or sometimes closed due to different reasons like political, technical, etc., but usually temporarily. All the stations are equipped with Quanterra digitizers and Streckeisen sensors, mostly STS2 with a few STS1. Aim of the network is to contribute to monitoring of one of the most active seismic regions of the World in terms of providing high quality real-time broadband data to the seismological community. Operations started with off-line field data collection and dial-up capabilities were later added at selected sites. At present these have been replaced with more efficient TCP connections that provide for real-time data collection over the whole network. This important technological upgrade allows a prompt contribution to the seismic monitoring of Italy and of most countries bordering the Mediterranean Sea, since data are exchanged in real-time with other seismological observatories. SeedLink protocol has been adopted for transmission. As for data archiving and distribution, a fast system for retrieving data has been developed. Continuous data streams, collected both from field data tapes and from real time transfer, are stored at the MedNet Data Center and are directly available at users’ request by the standard AutoDRM and NetDC protocols (in GSE and SEED formats respectively). Station metadata and continuous waveforms are archived in a MySQL database on RAID systems and backed up on DLT tapes. Presently, fully automatic network functions include: daily monitoring of state of health; triggered retrieval of event waveforms (with magnitude- and region- specific selection criteria), local and surface wave magnitude determination, and update of web pages (http://mednet.ingv.it) for events and station information. Rapid semiautomatic moment tensor solutions are calculated by means of a modified Harvard technique, which lowers the Mw threshold down to 4.5 for regional events in those areas with proper station coverage. For smaller earthquakes in Italy a new approach to moment tensor estimation, based on higher signal frequencies, is now being developed. Preliminary tests on earthquake recordings (not only MedNet stations) from the 2002 Molise, South Italy sequence have proved very successful.204 474 - PublicationRestrictedCalving event detection by observation of seiche effects on the Greenland fjords(2013)
; ; ; ;Walter, F.; Swiss Seismological Service, ETH Zürich, Switzerland; Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zürich, Switzerland ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Clinton, J.; Swiss Seismological Service, ETH Zürich, Switzerland; ; With mass loss from the Greenland ice sheet accelerating and spreading to higher latitudes, the quantification of mass discharge in the form of icebergs has recently received much scientific attention. Here, we make use of very low frequency (0.001-0.01 Hz) seismic data from three permanent broadband stations installed in the summers of 2009/2010 in northwest Greenland in order to monitor local calving activity. At these frequencies, calving seismograms are dominated by a tilt signal produced by local ground flexure in response to fjord seiching generated by major iceberg calving events. A simple triggering algorithm is proposed to detect calving events from large calving fronts with potentially no user interaction. Our calving catalogue identifies spatial and temporal differences in calving activity between Jakobshavn Isbræ and glaciers in the Uummannaq district some 200 km further north. The Uummannaq glaciers show clear seasonal fluctuations in seiche-based calving detections as well as seiche amplitudes. In contrast, the detections at Jakobshavn Isbræ show little seasonal variation, which may be evidence for an ongoing transition into winter calving activity. The results offer further evidence that seismometers can provide efficient and inexpensive monitoring of calving fronts.608 94 - PublicationRestrictedSeismic moment tensors of the April 2009, L'Aquila (Central Italy), earthquake sequence(2010-01)
; ; ; ; ; ; ;Pondrelli, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Salimbeni, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Morelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Ekstrom, G.; Lamont-Doherty Earth Observatory Columbia University NY USA ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia; ; ; ; ; On 2009 April 6, the Central Apennines were hit by an Mw= 6.3 earthquake. The region had been shaken since 2008 October by seismic activity that culminated in two foreshocks with Mw > 4, 1 week and a few hours before the main shock. We computed seismic moment tensors for 26 events with Mw between 3.9 and 6.3, using the Regional Centroid Moment Tensor (RCMT) scheme. Most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively. The focal mechanisms are all extensional, with a variable and sometimes significant strike-slip component. This geometry agrees with the NE–SW extensional deformation of the Apennines, known from previous seismic and geodetic observations. Events group into three clusters. Those located in the southern area have larger centroid depths and a wider distribution of T-axis directions. These differences suggest that towards south a different fault system was activated with respect to the SW-dipping normal faults beneath L’Aquila and more to the north.240 24 - PublicationUnknownAn Almost Fair Comparison Between Earthworm and SeisComp3(2012-07)
; ; ;Olivieri, Marco; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Clinton, John; Swiss Seismological Service ETH Zürich; The paper has not any abstract194 16 - PublicationOpen AccessIntermittent Sea Level Acceleration(2013)
; ; ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Spada, G.; Dipartimento di Scienze di Base e Fondamenti, Urbino University “Carlo Bo”; Using instrumental observations from the Permanent Service for Mean Sea Level (PSMSL), we provide a new assessment of the global sea{level acceleration for the last 2 centuries (1820-2010). Our results, obtained by a stack of tide gauge time series, con firm the existence of a global sea level acceleration (GSLA) and, coherently with independent assessments so far, they point to a value close to 0:01 mm/yr2. However, di fferently from previous studies, we discuss how change points or abrupt inflections in individual sea level time series have contributed to the GSLA. Our analysis, based on methods borrowed from econometrics, suggests the existence of two distinct driving mechanisms for the GSLA, both involving a minority of tide gauges globally. The first effectively implies a gradual increase in the rate of sea level rise at individual tide gauges, while the second is manifest through a sequence of catastrophic variations of the sea level trend. These occurred intermittently since the end of the 19th century and became more frequent during the last four decades.452 258 - PublicationOpen AccessAnomalous secular sea-level acceleration in the Baltic Sea caused by isostatic adjustment(2014)
; ; ; ;Spada, G.; Dip.to di Scienze di Base e Fondamenti, Università di Urbino, Urbino, Italy ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Galassi, G.; Dip.to di Scienze di Base e Fondamenti, Università di Urbino, Urbino, Italy; ; Observations from the global array of tide gauges show that global sealevel has been rising at an average rate of 1.5-2 mm/yr during the last ~150 years [Douglas 1991, Spada and Galassi 2012]. Although a global sea-level acceleration was initially ruled out [Douglas 1992], subsequent studies [Douglas 1997, Church and White 2006, Jevrejeva et al. 2008, Church and White 2011] have coherently proposed values of ~1 mm/year/century [Olivieri and Spada 2013]. More complex non-linear trends and abrupt sea-level variations have now also been recognized. Globally, these could manifest a regime shift between the late Holocene and the current rhythms of sea-level rise [Gehrels and Woodworth 2013], while locally they result from ocean circulation anomalies, steric effects and wind stress [Bromirski et al. 2011, Merrifield 2011]. Although isostatic readjustment affects the local rates of secular sea-level change [Milne and Mitrovica 1998, Peltier 2004], a possible impact on regional acceleration has been so far discounted [Douglas 1992, Jevrejeva et al. 2008, Woodworth et al. 2009] since the process evolves on a millennium time scale [Turcotte and Schubert 2002]. Here we report a previously unnoticed anomaly in the long-term sea-level acceleration of the Baltic Sea tide gauge records, and we explain it by the classical post-glacial rebound theory and numerical modeling of glacial isostasy. Contrary to previous assumptions, our findings demonstrate that isostatic compensation plays a role in the regional secular sea-level acceleration.344 125 - PublicationOpen AccessMedNet status report(2006-06-13)
; ; ; ; ; ; ; ; ; ; ; ;Mazza, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Mandiello, A. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Olivieri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Casale, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Scognamiglio, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Quintiliani, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Pietrangeli, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Pinzi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Perfetti, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Bucci, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Tozzi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; ; ; ; ; ; ; ; ; ; EMSC-CSEMMedNet is a network of very broadband seismic stations installed in countries bordering the Mediterranean area. The project started in 1987, with a final goal of 12-15 stations and a spacing of about 1000 km between stations. It was motivated both by research interest and by seismic hazard monitoring. The network presently comprises 23 operating stations, all of them equipped with state of the art seismographic stations. Presently, fully automatic network functions include: - daily monitoring of state of health; - data recover after link failures; - triggered retrieval of event waveforms; - update of web pages (http://mednet.ingv.it) for events and station information.235 70 - PublicationOpen AccessSmart working e Ricerca: il punto di vista dei Ricercatori e Tecnologi dell’INGV(2021-05-19)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Obiettivi: Le finalità di questo articolo sono quelle di sottolineare le specificità della Ricerca rispetto alla amministrazione. Metodologia: è stata svolta un’analisi qualitativa giuridico-normativa e una indagine online quantitativa a 585 ricercatori e tecnologi dell’INGV sullo smart working. Risultati: nell’articolo vengono richiamate le norme che affermano come le attività di ricerca e le attività gestionali debbono avere una valutazione diversa. Inoltre, il CCNL della sezione Ricercatori e Tecnologi già rende “smart” e “agile” il lavoro di ricerca senza ricadere nella legge sullo smart working. Le risposte all’indagine mostrano una forte coesione nel rivendicare i principi di autonomia e libertà della ricerca. Limiti e implicazioni: negli EPR si fa Ricerca e la Ricerca ha bisogno di flessibilità e specificità organizzativa rispetto ad una P.A. prevalentemente amministrativa e lo smart working mal si adatta al mondo della Ricerca. Originalità: il percorso bottom-up di rivendicazione dei diritti della ricerca, attraverso interviste online, è originale e innovativo per evidenziare l’analisi delle criticità del lavoro agile che non deve essere applicato senza considerare il modello rispondente alle proprie esigenze e caratteristiche.768 88 - PublicationOpen AccessA Seismological Study of the Sos Enattos Area—the Sardinia Candidate Site for the Einstein Telescope(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;The recent discovery of gravitational waves (GWs) and their potential for cosmic observations prompted the design of the future third‐generation GW interferometers, able to extend the observation distance for sources up to the frontier of the Universe. In particular, the European detector Einstein Telescope (ET) has been proposed to reach peak strain sensitivities of about 3×10−25Hz−1/2 in the 100 Hz frequency region and to extend the detection band down to 1 Hz. In the bandwidth [1,10] Hz, the seismic ambient noise is expected to represent the major perturbation to interferometric measurements, and the site that will host the future detectors must fulfill stringent requirements on seismic disturbances. In this article, we conduct a seismological study at the Italian ET candidate site, the dismissed mine of Sos Enattos in Sardinia. In the range between few mHz to hundreds of mHz, out of the detection bandwidth for ET, the seismic noise is compatible with the new low‐noise model (Peterson, 1993); in the [0.1,1] Hz bandwidth, we found that seismic noise is correlated with sea wave height in the northwestern Mediterranean Sea. In the [1,10] Hz frequency band, noise is mainly due to anthropic activities; within the mine tunnels (≃100m underground), its spectrum is compliant with the requirements of the ET design. Noise amplitude decay with depth is consistent with a dominance of Rayleigh waves, as suggested by synthetic seismograms calculated for a realistic velocity structure obtained from the inversion of phase‐ and group‐velocity dispersion data from array recording of a mine blasting. Further investigations are planned for a quantitative assessment of the principal noise sources and their spatiotemporal variations.509 365