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Tosi, Patrizia
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Tosi, Patrizia
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patrizia.tosi@ingv.it
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7103207181
37 results
Now showing 1 - 10 of 37
- PublicationOpen AccessEarthquake perception data highlight natural frequency details of Italian buildings(2023-04-17)
; ; ; ; ; As the distance from an earthquake increases, the percentage of people who do not feel it also increases. The average transition distance between ‘‘felt’’ and ‘‘not felt’’ reports is mainly determined by the magnitude and depth of the earthquake, but it also depends on the observation floor and building height. Buildings act as resonators and can amplify the shaking at specific frequencies.We analyzed over 286,000 crowdsourced reports to study the effect of floor and building height on earthquake perception. We found that, compared to average values, there is an increase in the percentage of ‘‘felt’’ reports on the highest floors and a decrease in the lowest floors of buildings of all heights.We determined the range within which an observer is likely to feel an earthquake (perception boundary) and examined how it varies with magnitude. We found that as the building height increases, people on higher floors perceive medium to high magnitude earthquakes progressively better than lower magnitude ones. We compared the perception boundary with a model of seismic response spectra to estimate the vibration frequency perceived by observers on each floor/ building height combination. Our results show that the value of the fundamental period increases with building height for the top floor, and that higher vibration modes become more evident for buildings with more than 6 stories. In addition, we observed that the height of the building also affects the vibration of the basement, with the frequency tending to decrease as the building height increases. Concerning macroseismic intensity estimation, we show that in tall buildings, observations made on both the upper and lower floors must be considered outside the normal range, and that earthquake perception also changes as a function of magnitude and distance, pointing out the importance of collecting an adequate number of observations to sample different locations of observers.38 8 - PublicationRestrictedSpace-time combined correlation between earthquakes and a new, self-consistent definition of aftershocks(2006)
; ; ; ; ;De Rubeis, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Loreto, V.; ”La Sapienza” University, Physics Department, and INFM, Center for Statistical Mechanics and Complexity, Roma, Italy ;Pietronero, L.; ”La Sapienza” University, Physics Department, and INFM, Center for Statistical Mechanics and Complexity, Roma, Italy ;Tosi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ;Bhattacharyya, P.Chakrabarti, B.Seismicity is recognized to be a complex natural phenomenon either in space, time and energy domains: earthquakes occur as a sudden energy release after a strongly variable time period of stress accumulation, in locations not deterministically defined, with magnitude range spanning over several orders. But seismicity is certainly not a pure random process: spatial locations of events clearly display correlations with tectonic structures at all scales (from plates borders to small faults settings); on the other hand time evolution is clearly linked with strongest shocks occurrence and energy distribution displays hierarchical features. Although it is still not possible to propose deterministic models for earthquakes, well established statistical relations constrain seismicity under very specific and intriguing relations.146 18 - PublicationRestrictedSeismic signal detection by fractal dimension analysis(1999)
; ; ; ; ; ; ;We introduce a new detection algorithm with improved local and regional seismic signal recognition. The method is based on the difference between seismic signals and background random noise in terms of fractal dimension D. We compare the new method extensively with standard methods currently in use at the Seismic Network of the lstituto Nazionale di Geofisica. Results from the comparisons show that the new method recognizes seismic phases detected by existing procedures, and in addition, it features a greater sensitivity to smaller signals, without an increase in the number of false alarms. The new method was tested on real continuous data and artificially simulated high-noise conditions and demonstrated a capability to recognize seismic signals in the presence of high noise. The efficiency of the method is due to a radically different approach to the topic, in that the assertion that a signal is fractal implies a relationship between the spectral amplitude of different frequencies. This relationship allows, for the fractal detector, a complete analysis of the entire frequency range under consideration.106 5 - PublicationOpen AccessStacked analysis of earthquake sequences: statistical space-time definition of clustering and Omori law behavior(2010)
; ; ; ;Tosi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;De Rubei, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Sbarra, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ;De Rubeis, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Teisseyre, R.The definition of the aftershocks sequence is still a debated topic. We here propose a study of the spatial and temporal variation of the earthquakes clustering and rate decay. We used five different seismic catalogues, characterized by specific spatial and magnitude ranges. They are respectively: world one, for a global analysis, Greek, Japanese, Californian and Italian regional catalogues in order to investigate different seismo-tectonic settings. A stacking procedure has been applied to characterize a typical sequence behavior and allowing the evaluation of changes over time intervals (107 296 - PublicationOpen AccessInfluence of strong electromagnetic discharges on the dynamics of earthquakes time distribution in the Bishkek test area (Central Asia)(2006-08)
; ; ; ; ;Chelidze, T.; Institute of Geophysics, Georgian Academy of Sciences, Tbilisi, Georgia ;De Rubeis, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Matcharashvili, T.; Institute of Geophysics, Georgian Academy of Sciences, Tbilisi, Georgia ;Tosi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; From 08/01/1983 to 28/03/1990, at the Bishkek ElectroMagnetic (EM) test site (Northern Tien Shan and Chu Valley area, Central Asia), strong currents, up to 2.5 kA, were released at a 4.5 km long electrical (grounded) dipole. This area is seismically active and a catalogue with about 14100 events from 1975 to 1996 has been analyzed. The seismic catalogue was divided into three parts: 1975-1983 first part with no EM experiments, 1983-1990 second part during EM experiments and 1988-1996 after experiments part. Qualitative and quantitative time series non- linear analysis was applied to waiting times of earthquakes to the above three sub catalogue periods. The qualitative approach includes visual inspection of reconstructed phase space, Iterated Function Systems (IFS) and Recurrence Quantification Analysis (RQA). The quantitative approach followed correlation integral calculation of reconstructed phase space of waiting time distribution, with noise reduction and surrogate testing methods. Moreover the Lempel- Ziv algorithmic complexity measure (LZC) was calculated. General dynamics of earthquakes’ temporal distribution around the test area, reveals properties of low dimensional non linearity. Strong EM discharges lead to the increase in extent of regularity in earthquakes temporal distribution. After cessation of EM experiments the earthquakes’ temporal distribution becomes much more random than before experiments. To avoid non valid conclusions several tests were applied to our data set: differentiation of the time series was applied to check results not affected by non stationarity; the surrogate data approach was followed to reject the hypothesis that dynamics belongs to the colored noise type. Small earthquakes, below completeness threshold, were added to the analysis to check results robustness.243 366 - PublicationOpen AccessRegional macroseismic field and intensity residuals of the August 24, 2016, Mw= 6.0 central Italy earthquake(2016)
; ; ; ; ; A macroseismic investigation of the August 24, 2016, Mw=6.0 Central Italy earthquake, was carried out through an online web survey. Data were collected through a macroseismic questionnaire available at the website www.haisentitoilterremoto.it, managed by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). Over 12000 questionnaires were compiled soon after the seismic occurrence, coming from over 2600 municipalities. A statistical analysis was applied tothe data collected in order to investigate the spatial distribution of intensity of the earthquake. The macroseismic intensity field (I) was described by identifying three main components: an isotropic component (I I ), a regional anisotropic component (I A ) and a local random variations parameter (ε). The anisotropic component highlighted specific and well-defined geographical areas of amplification and attenuation. In general, the area between the Adriatic coast and Apennines Chain was characterized by an amplification ofintensity, while the West side of the Apennines showed attenuation, in agreement with the domains foundby other works focused on the analysis of instrumental data. Moreover, the regional macroseismic field showed similarities with instrumental PGA data. The results of our analysis confirm the reliability of web questionnaire data.227 36 - PublicationOpen AccessAn analytic method for separating local from regional effects on macroseismic intensity(1995-03)
; ; ; ;Tosi, P.; Istituto Nazionale di Geofisica, Roma, Italy ;De Rubeis, V.; Istituto Nazionale di Geofisica, Roma, Italy ;Gasparini, C.; Istituto Nazionale di Geofisica, Roma, Italy; ; nterpretation of macroseismic data is hazardous, due to its qualitative nature. This, linked with errors in eval- uation,) and the variations of local intensity, makes it difficult to draw valid conclusions. This study presents a statistical method as the basis for distinguishing the diverse components that constitute a macroseismic field. The method is based on the polar transformation of the coordinate system and on the analysis of the fractal di- mension of the intensity values, exposed to the gradually increasing action of a two-dimensional filter. The fractal dimension is shown to be an ideaI parameter with which to measure out the filtering process in order to separate the local components from the regional trend. This method has been applied to two Italian events and to an earthquake which took pIace in the Former Yugoslavian Republic of Macedonia (FYROM).155 342 - PublicationOpen AccessLocal seismicity in Rome (Italy): recent results from macroseismic evidences(1996-12)
; ; ; ;Tertulliani, A.; Istituto Nazionale di Geofisica, Roma, Italy ;Tosi, P.; Istituto Nazionale di Geofisica, Roma, Italy ;De Rubeis, V.; Istituto Nazionale di Geofisica, Roma, Italy; ; This paper presents the results obtained from the study of the macroseismic effects of the June 12, 1995 Rome earthquake. The event, MD = 3.8, provoked VI degree MCS effects in neighbourhoods of Southern Rome. This earthquake is important within the framework of seismicity in the Rome area, as it is the first noteworthy one ever to be recorded in the instrumental age, and provides a good comparison with historical earthquakes which have occurred in the same area. The filtering procedure performed on the macroseismic field reveals out the anomalies of the attenuation pattern and the site effect. The results reconfirm what has only recently emerged from the analysis of historical earthquakes, i.e. Rome is affected by local seismicity, that can cause damage in the southern neighbourhoods and the downtown area, especially where the site contributes to the amplification of the effects.149 244 - PublicationOpen AccessSpace-time combined correlation integral and earthquake interactions(2004)
; ; ; ; ;Tosi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;De Rubeis, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Loreto, V.; Centro INFM di Meccanica Statistica e Complessità, Università La Sapienza, Roma, Italy ;Pietronero, L.; Centro INFM di Meccanica Statistica e Complessità, Università La Sapienza, Roma, Italy; ; ; Scale invariant properties of seismicity argue for the presence of complex triggering mechanisms. We propose a new method, based on the space-time combined generalization of the correlation integral, that leads to a self-consistent visualization and analysis of both spatial and temporal correlations. The analysis has been applied on global medium-high seismicity. Results show that earthquakes do interact even on long distances and are correlated in time within defined spatial ranges varying over elapsed time. On that base we redefine the aftershock concept.183 284