// +author:o amoroso +author:amoroso 
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{userid:"maercklin", "refid":"130","repocollections":"","attachment":"","_thumb":"","articletype":"article","sectionheading":"","title":"S-wave identification by polarization filtering and waveform coherence analyses","year":"2012","author":"O Amoroso, N Maercklin, A Zollo","journal":"Bulletin of the Seismological Society of America","volume":"102","number":"2","pages":"854-861","month":"April","doi":"10.1785\/0120110140","pubmed":"","pdflink":"","urllink":"","abstract":"High-resolution imaging with microseismic events requires the use of large and consistent data sets of seismic phase arrival times. In particular the S-phase is important to derive physical parameters of the subsurface. Typically this phase is identified on one of the horizontal seismogram components by a change of signal amplitude and frequency as compared to the previous P-phase. However, reliable S-phase identification can be difficult for local events because of a signal overlap with the P coda, the presence of converted phases, and possible S-wave splitting due to anisotropy. In this study we propose a new data processing technique aiming at uniquely identifying the S phase arrival using all available records from a seismic network. The technique combines polarization analysis of single three components recordings of an event with analysis of lateral waveform coherence across the network. This makes it possible to construct seismic sections in which the first arrival is the S-phase. This graphical representation can support an operator in both the analysis of single events and in semi-automatic analyses of large datasets. In addition, an automated stacking velocity analysis provides S-wave velocities from these sections. We demonstrate the applicability of this technique using synthetic seismograms, and we evaluate the efficacy on a dataset of three-component velocimeter records from local earthquakes of the Campania-Lucania Apennines (southern Italy) recorded by the Irpinia Seismic Network (ISNet).","note":"","tags":"","weight":"130"}
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{userid:"maercklin", "refid":"126","repocollections":"","attachment":"","_thumb":"","articletype":"inproceedings","sectionheading":"","title":"S-wave identification by polarization filtering and waveform coherence analysis","year":"2011","author":"O Amoroso, N Maercklin, A Zollo","booktitle":"European Geosciences Union, Geophysical Research Abstracts Vol. 13","editor":"","pages":"9048","organization":"European Geosciences Union","address":"Wien, Austria","publisher":"","doi":"","pubmed":"","pdflink":"","urllink":"https:\/\/ui.adsabs.harvard.edu\/abs\/2011EGUGA..13.9048A","abstract":"The increasing number of seismic networks with high density of stations offers an ever larger amount of three-component recordings of earthquakes in a wide range of magnitudes. The analysis of these data can provide detailed information on both the propagation medium and the seismic source. In particular, the S-wave velocity is a key parameter for the understanding of the compositional and physical state of the lithosphere. On the other hand this requires a tool for identifying the seismic phase.\r\nThe S-phase can be identified by a change in amplitude and frequency content of the signal with respect to the P-phase. The precise identification of S-phase is generally made difficult by the interference of P-coda waves, the arrival of converted phases generated beneath the recording site or the S-wave splitting. These factors can lead the operator to misidentify the phase or, very often, to abandon reading itself.\r\nIn this study, we propose a data processing technique aimed at univocally identifying the arrival-time of the S-phase by using three component recordings available at all stations of a seismic network. The proposed technique provides an additional support to the operators to be used for both the analysis of a single event or for the massive, quasi-automatic analysis of huge datasets.\r\nThe technique is based on the combination of a polarization detector mainly used in passive seismology and the move-out and stack analysis of trace gathers as for the velocity analysis in exploration seismics. The processing consists of four main steps. The first consists in P-phase picking and event location. The second step is the setting-up polarization detector: we rotate the three-component seismograms into the ray-coordinate system (L,Q,T), using theoretical backazimuths and incidence angles from P-phase polarizations. In the new system we calculate the directivity D, which is defined as the normalized angle between the P-phase polarization L and the actual polarization direction, the rectilinearity R and the ratio between transverse and total energy H. The product of the squares of the three filter operators yields the characteristic function (CF) for S-wave detection, with which we weight the transverse component traces. The third step deals with the seismic section analyses. Once the CF has been defined, the waveforms are displayed in common receiver gathers as a function of hypocentral distance. On each section we evaluate the lateral coherence of S-phase through a linear velocity analysis. The resulting S-wave velocity can be used to compute a reference pick for the S-phase at each station. In the fourth step an automatic picker is used around the reference value.\r\nIn the present study, we apply our S-wave detection-picking approach to a dataset of 5675 three component, ground velocity recordings of 626 local earthquakes with magnitude ML (0.1, 3.2), which occurred in southern Italy and were recorded by the Irpinia Seismic Network in the period December 2007 to March 2010. To assess the performance of the proposed methodology, we compare the residuals of the automatic and the theoretical arrivals with the residuals between the manual readings and the theoretical arrivals. The dispersion of the residual distributions obtained from the refined picking is consistent with the dispersion obtained from the manual picks, while the total number of available readings is increased.","note":"","tags":"","weight":"126"}
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{userid:"maercklin", "refid":151,"repocollections":"","attachment":"","_thumb":"","articletype":"misc","sectionheading":"Posters and presentations","title":"Analysis of induced seismicity at The Geysers geothermal field, California","year":"2013","author":"A Orefice, A Emolo, N Maercklin, E Matrullo, O Amoroso, V Convertito, N Sharma, A Zollo","howpublished":"GEISER Meeting, Naples, Italy","doi":"10.13140\/2.1.4725.8560","pubmed":"","pdflink":"","urllink":"","abstract":"","note":"","tags":"","weight":151}
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{userid:"maercklin", "refid":"150","repocollections":"","attachment":"","_thumb":"","articletype":"misc","sectionheading":"Posters and presentations","title":"Time-dependent seismic hazard studies in \"The Geysers\" geothermal area","year":"2013","author":"N Sharma, V Convertito, A Emolo, N Maercklin, E Matrullo, O Amoroso, A Orefice, A Zollo","howpublished":"GEISER Meeting, Naples, Italy","doi":"10.13140\/2.1.1317.9844","pubmed":"","pdflink":"","urllink":"","abstract":"The continuous industrial operations like fluid injection and extraction alters the stresses in upper earth crust. As the consequence, induced seismicity has gained considerable attention among seismologists, worldwide. The Geysers is the largest vapor-dominated geothermal field in the world, situated about 120 km north of San Francisco, California. No ground-motion prediction equations and seismic hazard maps were available specifically for this area before our study. Ground-motion prediction equations (GMPEs) are estimated for The Geysers geothermal area using data recorded at 29 stations of the Berkley-Geysers network during the period September 2007 through November 2010. Non-linear mixed effect regression method is used to compute GMPEs for peak ground velocity (PGV), peak ground acceleration (PGA), and 5% damped spectral acceleration SA(T) at T = 0.2s, 0.5s, and 1.0s. We demonstrated that the inter-event residuals represents misfit due to the average source effects and also reflects various factors like stress drop and\/or variation of slip in time and space, which are not captured by including magnitude, focal mechanism and source depth. On the other hand, intra-event residual represents misfit due path and site effects (crustal heterogeneity, geological structure and near surface layering) which modify the waveform (in terms of amplitude and frequency) and are not captured by distance metric and site classification based on the average shear wave velocity. The two-step approach used to compute GMPEs, demonstrates that even if information about local geology is not available, the method of introducing site\/station effect correction is effective and shows significant improvement in the model. Results from time-dependent probabilistic seismic hazard analysis (PSHA) demonstrated that hazard is not constant with time and space. We also propose that time-dependent probabilistic seismic hazard analysis can be used to monitor the effect of ongoing field operations. The variations in seismic hazard with time can be a consequence of the variation of both seismicity rate and Gutenberg-Richter b-value which can be related to the rate of fluid injection. We concluded that, for the exposure time taken into account (i.e., 2 months), as a conservative limit, peak-ground acceleration values corresponding to the lowest probability of exceedance (e.g., 30%) must not exceed to ensure the safe field operations. We also suggested that the proposed technique can be tested at other geothermal areas or in regions, where seismicity is induced for example by hydrocarbon exploitation or carbon dioxide storage.","note":"","tags":"","weight":150}
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{userid:"maercklin", "refid":"135","repocollections":"","attachment":"","_thumb":"","articletype":"inproceedings","sectionheading":"","title":"Analysis of induced seismicity at The Geysers geothermal field, California","year":"2012","author":"A Emolo, N Maercklin, E Matrullo, A Orefice, O Amoroso, V Convertito, N Sharma, A Zollo","booktitle":"AGU Fall Meeting","editor":"","pages":"S43D-2500","organization":"American Geophysical Union","address":"San Francisco, California","publisher":"","doi":"","pubmed":"","pdflink":"","urllink":"https:\/\/ui.adsabs.harvard.edu\/abs\/2012AGUFM.S43D2500E","abstract":"Fluid injection, steam extraction, and reservoir stimulation in geothermal systems lead to induced seismicity. While in rare cases induced events may be large enough to pose a hazard, on the other hand the microseismicity provides information on the extent and the space-time varying properties of the reservoir. Therefore, microseismic monitoring is important, both for mitigation of unwanted effects of industrial operations and for continuous assessment of reservoir conditions. Here we analyze induced seismicity at The Geysers geothermal field in California, a vapor-dominated field with the top of the main steam reservoir some 1-3 km below the surface. Commercial exploitation began in the 1960s, and the seismicity increased with increasing field development. We focus our analyses on induced seismicity recorded between August 2007 and October 2011. Our calibrated waveform database contains some 15000 events with magnitudes between 1.0 and 4.5 and recorded by the LBNL Geysers\/Calpine surface seismic network. We associated all data with events from the NCEDC earthquake catalog and re-picked first arrival times. Using selected events with at least 20 high-quality P-wave picks, we determined a minimum 1-D velocity model using VELEST. A well-constrained P-velocity model shows a sharp velocity increase at 1-2 km depth (from 3 to 5 km\/s) and then a gradient-like trend down to about 5 km depth, where velocities reach values of 6-7 km\/s. The station corrections show coherent, relatively high, positive travel time delays in the NW zone, thus indicating a strong lateral variation of the P-wave velocities. We determined an average Vp-to-Vs ratio of 1.67, which is consistent with estimates from other authors for the same time period. The events have been relocated in the new model using a non-linear probabilistic methods. The seismicity appears spatially diffused in a 15x10 km2 area elongated in NW-SE direction, and earthquake depths range between 0 and 6 km. As in previous seismicity studies of this geothermal field, we find that events occurring in the NW sector are on average deeper than in the SE area. To infer the present stress regime, we computed focal mechanisms of a large event data set with M > 2, using P-wave first-arrival polarities. The found fault-plane solutions show a dominant strike-slip and normal faulting mechanisms, with P and T axes coherently oriented with expected regional stress field for the area. We also determined the main seismic source parameters from a multi-step, iterative inversion of P-wave displacement spectra, assuming a four-parameters spectral model and a constant-Q attenuation mechanism. In particular, we computed seismic moments, source radii and stress drops. We observe a self-similar scaling of source parameters in the whole investigated magnitude range, with a nearly constant stress-drop of 20 and 120 MPa depending on the use of the Brune (1970) or Madariaga (1976) source model, respectively.","note":"","tags":"","weight":"135"}
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{userid:"maercklin", "refid":"123","repocollections":"","attachment":"","_thumb":"","articletype":"misc","sectionheading":"Posters and presentations","title":"Velocity models and refined estimates of micro-earthquake source parameters for the Irpinia region, Southern Italy","year":"2010","author":"T A Stabile, O Amoroso, R De Matteis, N Maercklin, E Matrullo, A Orefice, G Pasquale, C Satriano, A Zollo","howpublished":"DPC-INGV 2007-09 Final Meeting of Seismological Projects Roma, Italy","doi":"10.13140\/2.1.4889.6967","pubmed":"","pdflink":"","urllink":"","abstract":"This work concerns the high-resolution study of Irpinia region through the refined estimates of micro-earthquake source parameters in the magnitude range 1<M<3 and the determination of appropriate velocity models. Using accurate manual picks we first located about 900 events using a non-linear global approach and after we refined locations considering a double-difference technique. Moreover we relocated subsets of similar event using also high-precision differential arrivals from cross-correlation differential arrival times of P- and S-waves. Finally we propose an innovative technique to identify S-waves on seismograms since the complexity of the area produces phases that overlap the first S-wave arrival.","note":"","tags":"","weight":"123","booktitle":"DPC-INGV 2007-09 Final Meeting of Seismological Projects","editor":"","pages":"","organization":"","address":"Roma, Italy","publisher":""}
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{userid:"maercklin", "refid":"133","repocollections":"","attachment":"","_thumb":"","articletype":"misc","sectionheading":"Posters and presentations","title":"Real time seismic monitoring and data analysis of the Campania-Lucania Apennines","year":"2012","author":"TA Stabile, O Amoroso, R De Matteis, A Emolo, G Festa, G Iannaccone, N Maercklin, E Matrullo, A Orefice, M Vassallo, A. Zollo","howpublished":"38th Workshop of the International School of Geophysics: Global challenges for seismological data analysis Erice, Italy","doi":"","pubmed":"","pdflink":"","urllink":"","abstract":"The continuous seismic monitoring of the Campania-Lucania Apennines by the ISNet (Irpinia Seismic Network) allowed us to observe since 2005 about 1500 microearthquakes with a maximum moment magnitude Mw=3.7. Therefore, ISNet constitutes a unique field laboratory to monitor and study the source processes in a complex seismogenic region characterized by prevalent normal-faulting seismicity and capable of generating earthquakes up to magnitude 7. Here we present the on-going activities at the RISSC-Lab research group for the analysis of seismic data by advanced techniques. In particular, these research activities range from the very accurate earthquake locations and refined estimations of source parameters to the study of the stress regime of the monitored region. We also built real time analysis tools apt to well identify the S-wave first arrival time, detect similar events in a swarm by an event template, and monitor variations of the Vp\/Vs ratio.","note":"","tags":"","weight":"133","booktitle":"38th Workshop of the International School of Geophysics: Global challenges for seismological data analysis","editor":"","pages":"","organization":"","address":"Erice, Italy","publisher":""}
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{userid:"maercklin", "refid":"118","repocollections":"","attachment":"","_thumb":"","articletype":"misc","sectionheading":"Posters and presentations","title":"RU S5\/6 \u2013 DSF-UniNA: Research activities in the frame of the S5 project","year":"2009","author":"A Zollo, G Festa, N Maercklin, C Satriano, O Amoroso, A Bobbio, G Iannaccone, E Matrullo, A Orefice, T A Stabile, and M Vassallo","howpublished":"DPC-INGV 2007-09 Final Meeting of Seismological Projects Roma, Italy","doi":"","pubmed":"","pdflink":"","urllink":"","abstract":"The research activity of RU6 is targeted at the Irpinia test site, one of the most active seismic zones of the Southern Apennines. Large destructive earthquakes occurred both in historical and recent times in this region, which was struck in 1980 by the strongest event (Mw = 6.9) of the past century in the Southern Apennines. The main research facility of the area is the Irpinia Seismic Network (ISNet), managed by AMRA (Analysis and Monitoring of Environmental Risks). ISNet is a high-density, high-dynamics seismic and accelerometric network, built on innovative technological and methodological concepts, and focused on real-time data acquisition, processing and modeling. ISNet complements the INGV network in the region, making the Irpinia test site one of the highest instrumented seismic areas in Italy and an ideal site for experimenting new approaches for seismic monitoring and imaging of active fault systems.\r\nIn the framework of S5 project, the research carried by RU6 is based on the real-time and off-line analysis of noise and microearthquake data collected by the ISNet and INGV networks. In particular, we are actively developing and experimenting new methodologies in the following research fields:\r\n(a) Seismic noise analysis and green functions: use of the random wavefield to retrieve images of the sub-soil through cross-correlation and stacking of continuous recorded signal; study of the ambient noise level and the seismic detection threshold for ISNet.\r\n(b) Refined estimates of micro-earthquake source parameters: retrieval of high resolution images of the fault system through the accurate determination of location, size and fault mechanisms in the magnitude range 1<M<3; study of the scaling relationships for seismic moment, radiated energy, corner-frequency, stress drop and source radius.\r\n(c) Reflection seismology applied to earthquake data: use of reflection tomography to infer depths and geometries of subsurface reflectors, and to constrain the velocity structure below the seismogenic zone.\r\nThe central access point for the real-time and off-line analysis results is the ISNet bulletin (http:\/\/isnet.na.infn.it\/cgi-bin\/isnet-events\/isnet.cgi) where full waveforms and source parameters for automatically detected and manually revised events are available.","note":"","tags":"","weight":"118","booktitle":"DPC-INGV 2007-09 Annual Meeting of Seismological Projects","editor":"","pages":"","organization":"","address":"Roma, Italy","publisher":""}
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{userid:"maercklin", "refid":"148","repocollections":"","attachment":"","_thumb":"","articletype":"techreport","sectionheading":"","title":"Guidelines for techniques\/methodologies for seismological investigations to be applied in future EGS operations, developed on the basis of successful analyses of past sequences","year":"2013","author":"A Zang, V Oye, J Albaric, N Deichmann, B Goertz-Allmann, M Cal\u00f2, C Dorbath, K \u00c1g\u00fastsson, O Fl\u00f3venz, M Bohnhoff, G Kwiatek, A Zollo, O Amoroso, V Convertito, A Emolo, N Maercklin, E Matrullo A Orefice, N Sharma","institution":"AMRA, ETHZ, EOST, GFZ, ISOR, NORSAR","series":"GEISER Deliverable Report","number":"D3.3","address":"","doi":"10.5281\/zenodo.1255632","pubmed":"","pdflink":"https:\/\/zenodo.org\/records\/1255632\/files\/GEISER_D3.3.pdf?download=1","urllink":"","abstract":"","note":"Grant Agreement no. 241321-2: Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs (GEISER)","tags":"","weight":148}
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{userid:"nicoletta.biglia", "refid":105,"repocollections":"","attachment":"","_thumb":"","articletype":"article","sectionheading":"","title":"Breast cancer \"tailored follow-up\" in Italian oncology units: a web-based survey.","year":"2014","author":"Natoli C, Brocco D, Sperduti I, Nuzzo A, Tinari N, De Tursi M, Grassadonia A, Mazzilli L, Iacobelli S, Gamucci T, Vici P; \u201cFOLLOW-UP\u201d Study Group.,Natoli C, Adamo V, Airoldi M, Amoroso D, Angelini F, Angiolini C, Angiolucci G, Ardizzoia A, Baldini E, Ballardini P, Barni S, Barone C, Battelli N, Bernardi D, Bianchetti S, Bianco N, Biglia N, Bilancia D, Biti G, Boni C, Bordonaro R, Botta M, Bretti S, Brunello A, Brunetti C, Bruno D, Bucci E, Buzzoni R, Cagossi K, Cappelletti C, Cappuzzo F, Cardillo F, Carroccio R, Cascinu S, Cavanna L, Cianchetti E, Clerico M, Contu A, Corsi D, Cortesi L, Cretella E, Crispino S, Di Lieto M, Di Lullo L, Durini E, Fabi A, Failla G, Fattorusso S, Ferra\u00f9 F, Ferro A, Ficorella C, Fogazzi G, Foglietta J, Francini G, Fusco O, Gennari A, Ghiani M, Gianni L, Giordano M, Giotta F, Giuliani R, Gori S, Graiff C, Guarneri V, Guarneri D, Guglielmi F, Landriscina M, Laudadio L, Lombardo M, Longo F, Macellari G, Madeddu C, Magnanini S, Maiorino L, Mangiameli A, Marini G, Massidda B, Mattioli R, Michelotti A, Molino A, Montesarchio V, Morale A, Murgo R, Naso G, Natale D, Orditura M, Orr\u00f9 S, Pace R, Palazzo A, Palma F, Pancotti A, Pandoli G, Papaldo P, Parisi AM, Passalacqua R, Pellegrino A, Perrucci B, Proietti E, Recchia F, Riccardi F, Rispoli AI, Rocca A, Romaniello I, Rossetti R, Rossi D, Rosti G, Ruggeri EM, Russo A, Savarino A, Savastano C, Scognamiglio G, Scognamiglio M, Seminara P, Serrachini S, Sidoti V, Silva RR, Surace G, Tomao S, Tonini G, Trenta P, Turazza M, Valenza R, Veltri E, Zampa G, Zaniboni A, Zanirato S.","journal":"Plos One","volume":"9","number":"4","pages":"e94063","month":"april","doi":"","pubmed":"24714591","pdflink":"http:\/\/www.plosone.org\/article\/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0094063&representation=PDF","urllink":"http:\/\/www.plosone.org\/article\/info%3Adoi%2F10.1371%2Fjournal.pone.0094063","abstract":"PURPOSE:\r\n\r\nBreast cancer follow-up procedures after primary treatment are still a controversial issue. Aim of this study was to investigate, through a web-based survey, surveillance methodologies selected by Italian oncologists in everyday clinical practice.\r\nMETHODS:\r\n\r\nReferents of Italian medical oncology units were invited to participate to the study via e-mail through the SurveyMonkey website. Participants were asked how, in their institution, exams of disease staging and follow-up are planned in asymptomatic women and if surveillance continues beyond the 5th year.\r\nRESULTS:\r\n\r\nBetween February and May 2013, 125 out of 233 (53.6%) invited referents of Italian medical oncology units agreed to participate in the survey. Ninety-seven (77.6%) referents state that modalities of breast cancer follow-up are planned according to the risk of disease progression at diagnosis and only 12 (9.6%) oncology units apply the minimal follow-up procedures according to international guidelines. Minimal follow-up is never applied in high risk asymptomatic women. Ninety-eight (78.4%) oncology units continue follow-up in all patients beyond 5 years.\r\nCONCLUSIONS:\r\n\r\nOur survey shows that 90.4% of participating Italian oncology units declare they do not apply the minimal breast cancer follow-up procedures after primary treatment in asymptomatic women, as suggested by national and international guidelines. Interestingly, about 80.0% of interviewed referents performs the so called \"tailored follow-up\", high intensity for high risk, low intensity for low risk patients. There is an urgent need of randomized clinical trials able to determine the effectiveness of risk-based follow-up modalities, their ideal frequency and persistence in time.","note":"","tags":"","weight":105}
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