In this paper we study the potential of symmetry attribute analysis applied to the phase component of electric field observations of marine controlled-source electromagnetic data. The effectiveness of symmetry attribute analysis on the phase component of marine controlled-source electromagnetic data in detecting the boundaries of resistive layer(s), such as hydrocarbon accumulation, is investigated. A comparison between symmetry attribute analysis on the phase and magnitude component of 2.5D synthetic data and a real data set is also discussed. The results presented a clear response indicative of the locations of the subsurface resistors. The phase symmetry attribute analysis proved to be effective for qualitative detection of the lateral extent of embedded resistors.
{"title":"Investigation of symmetry attribute analysis on the phase measurements of marine controlled-sourceelectromagnetic surveys","authors":"A. H. H. Ezieke, A. H. Mansi, G. Bernasconi","doi":"10.4430/bgta0183","DOIUrl":"https://doi.org/10.4430/bgta0183","url":null,"abstract":"In this paper we study the potential of symmetry attribute analysis applied to the phase component of electric field observations of marine controlled-source electromagnetic data. The effectiveness of symmetry attribute analysis on the phase component of marine controlled-source electromagnetic data in detecting the boundaries of resistive layer(s), such as hydrocarbon accumulation, is investigated. A comparison between symmetry attribute analysis on the phase and magnitude component of 2.5D synthetic data and a real data set is also discussed. The results presented a clear response indicative of the locations of the subsurface resistors. The phase symmetry attribute analysis proved to be effective for qualitative detection of the lateral extent of embedded resistors.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70798194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G.Martinelli Gmartinelli, A. Dadomo, J. Heinicke, F. Italiano, R. Petrini, L. Pierotti, A. Riggio, M. Santulin, F. Slejko, A. Tamaro
Hydrological and hydrogeochemical observations (piezometry, chemistry, electric properties, etc.) carried out in groundwaters in Italy in the past 40 years have been recovered and processed. Available data time series recorded by government agencies, scientific institutions and independent researchers in the field of groundwater and geochemical monitoring in 5480 different sites have been recovered, systematized and processed. Meteorological data useful for data evaluation have been recovered too. Some possible precursors have been identified but the relatively high amount of earthquakes not preceded by hydrologic or geochemical anomalies suggest the need to consider all together geophysical and geochemical parameters for future researches. Highest amount of data collected by manual sampling were found in the Lombardy, Veneto, and Emilia-Romagna regions, while most of automatically recorded data were found in the Tuscany region.
{"title":"Recovery and processing of hydrological and hydrogeochemical parameters for researches on earthquake short-term precursors in Italy","authors":"G.Martinelli Gmartinelli, A. Dadomo, J. Heinicke, F. Italiano, R. Petrini, L. Pierotti, A. Riggio, M. Santulin, F. Slejko, A. Tamaro","doi":"10.4430/BGTA0147","DOIUrl":"https://doi.org/10.4430/BGTA0147","url":null,"abstract":"Hydrological and hydrogeochemical observations (piezometry, chemistry, electric properties, etc.) carried out in groundwaters in Italy in the past 40 years have been recovered and processed. Available data time series recorded by government agencies, scientific institutions and independent researchers in the field of groundwater and geochemical monitoring in 5480 different sites have been recovered, systematized and processed. Meteorological data useful for data evaluation have been recovered too. Some possible precursors have been identified but the relatively high amount of earthquakes not preceded by hydrologic or geochemical anomalies suggest the need to consider all together geophysical and geochemical parameters for future researches. Highest amount of data collected by manual sampling were found in the Lombardy, Veneto, and Emilia-Romagna regions, while most of automatically recorded data were found in the Tuscany region.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70797502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Tramutoli, R. Corrado, C. Filizzola, N. Genzano, M. Lisi, N. Pergola
This review paper reports the main contributions and results achieved after more than 30 years of studies on the possible relationships among space-time variation of Earth’s thermally emitted radiation, measured by satellite sensors operating in the Thermal InfraRed (TIR) spectral range (8-14 m), and earthquake occurrence. Focus will be given on the different existing methods/models to: 1) discriminate a possible pre-seismic TIR anomaly from all the other TIR signal fluctuations; 2) correlate such anomalies with space, time and magnitude of earthquakes; 3) physically justify such a correlation.
{"title":"From visual comparison to robust satellite techniques: 30 years of thermal infrared satellite data analyses for the study of earthquake preparation phases","authors":"V. Tramutoli, R. Corrado, C. Filizzola, N. Genzano, M. Lisi, N. Pergola","doi":"10.4430/BGTA0149","DOIUrl":"https://doi.org/10.4430/BGTA0149","url":null,"abstract":"This review paper reports the main contributions and results achieved after more than 30 years of studies on the possible relationships among space-time variation of Earth’s thermally emitted radiation, measured by satellite sensors operating in the Thermal InfraRed (TIR) spectral range (8-14 m), and earthquake occurrence. Focus will be given on the different existing methods/models to: 1) discriminate a possible pre-seismic TIR anomaly from all the other TIR signal fluctuations; 2) correlate such anomalies with space, time and magnitude of earthquakes; 3) physically justify such a correlation.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70797578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The problem of aquifers and soil salinity is addressed in the coastal area of Muravera (SE Sardinia, Italy) with the combined use of electrical resistivity and induced polarization measurements along three lines, and with 41 Transient Electromagnetic (TEM) soundings distributed in the study area. The resistivity and chargeability sections provide a detailed information on the hydrogeological conditions in the first 20 60 m depth, clarifying the role of both clay and salt water and eventually confirming the local near-surface hydrogeological model. The resistivity maps obtained for different depth ranges by TEM data inversion, give a clear and effective representation of the saline contamination both laterally and down to a depth of about 70 m, over the whole investigated area. The combination of the geophysical techniques (resistivity tomography with Induced Polarization measurements, integrated with TEM soundings) proves very effective as an approach for soil and water salination monitoring.
{"title":"Integrated interpretation of IP and TEM data for salinity monitoring of aquifers and soil in the coastal area of Muravera (Sardinia, Italy)","authors":"R. Balia, A. Viezzoli","doi":"10.4430/BGTA0136","DOIUrl":"https://doi.org/10.4430/BGTA0136","url":null,"abstract":"The problem of aquifers and soil salinity is addressed in the coastal area of Muravera (SE Sardinia, Italy) with the combined use of electrical resistivity and induced polarization measurements along three lines, and with 41 Transient Electromagnetic (TEM) soundings distributed in the study area. The resistivity and chargeability sections provide a detailed information on the hydrogeological conditions in the first 20 60 m depth, clarifying the role of both clay and salt water and eventually confirming the local near-surface hydrogeological model. The resistivity maps obtained for different depth ranges by TEM data inversion, give a clear and effective representation of the saline contamination both laterally and down to a depth of about 70 m, over the whole investigated area. The combination of the geophysical techniques (resistivity tomography with Induced Polarization measurements, integrated with TEM soundings) proves very effective as an approach for soil and water salination monitoring.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70797778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Charikleia G. Gkarlaouni, V. Karakostas, A. Kilias, S. Lasocki, E. Papadimitriou
Seismicity in the broader area of Mygdonia basin in northern Greece is lately characterized by the absence of strong events along active seismogenic faults known to have been activated in the past. Small to moderate magnitude earthquakes not exceeding ML4.8 have occurred in the last three decades. In this study, earthquakes occurred in 2000 and 2013 and recorded by the Hellenic Seismological network were investigated. Available Pand Sseismic wave arrivals were used for relocation in order to obtain accurately determined earthquake focal coordinates. For this scope, a Wadati diagram was constructed and a Vp/Vs ratio equal to 1.78 as well as time delays were included in the Hypoinverse process for the estimation of the focal coordinates. In the case of strong spatial or temporal clustering among earthquakes, the HypoDD algorithm was also employed for further improving location accuracy. The relocated seismicity was used in order to reveal the structural and geometrical properties of the local fault population and identify seismogenic faults deprived of a clear surface expression. For this reason, cross sections perpendicular to the main axis of the rupture zones were created, and finally a correlation between the kinematic properties and the current stress field was attempted. It is evident that in the absence of strong earthquakes, microseismicity is the only, however fundamental information to be exploited for the identification of active faults and the hazard assessment since small earthquakes are concentrated in areas with a significant potential for a future strong earthquake.
{"title":"Fault population recognition through microseismicity in Mygdonia region (northern Greece)","authors":"Charikleia G. Gkarlaouni, V. Karakostas, A. Kilias, S. Lasocki, E. Papadimitriou","doi":"10.4430/BGTA0153","DOIUrl":"https://doi.org/10.4430/BGTA0153","url":null,"abstract":"Seismicity in the broader area of Mygdonia basin in northern Greece is lately characterized by the absence of strong events along active seismogenic faults known to have been activated in the past. Small to moderate magnitude earthquakes not exceeding ML4.8 have occurred in the last three decades. In this study, earthquakes occurred in 2000 and 2013 and recorded by the Hellenic Seismological network were investigated. Available Pand Sseismic wave arrivals were used for relocation in order to obtain accurately determined earthquake focal coordinates. For this scope, a Wadati diagram was constructed and a Vp/Vs ratio equal to 1.78 as well as time delays were included in the Hypoinverse process for the estimation of the focal coordinates. In the case of strong spatial or temporal clustering among earthquakes, the HypoDD algorithm was also employed for further improving location accuracy. The relocated seismicity was used in order to reveal the structural and geometrical properties of the local fault population and identify seismogenic faults deprived of a clear surface expression. For this reason, cross sections perpendicular to the main axis of the rupture zones were created, and finally a correlation between the kinematic properties and the current stress field was attempted. It is evident that in the absence of strong earthquakes, microseismicity is the only, however fundamental information to be exploited for the identification of active faults and the hazard assessment since small earthquakes are concentrated in areas with a significant potential for a future strong earthquake.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70797984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Lavecchia, R. Nardis, G. Costa, L. Tiberi, F. Ferrarini, D. Cirillo, F. Brozzetti, P. Suhadolc
We present the results of an interdisciplinary study aimed at defining the geometry of the fault segments activated by the Emilia 2012 thrust sequence (MW up to 6.1), which are located at the front of the Ferrara Arc (northern Italy) and partially overlap with an area undergoing hydrocarbon exploitation since 1980 (Cavone oil field). We relocate 40 well-recorded earthquakes with MW prevailingly ≥4.0 in the time interval from May 20 to June 12, 2012, plus an event that occurred in a nearby area on July 17, 2011 (MW 5.0). The geological and seismotectonic setting of the area is discussed, some interpretative geological sections across the hypocentral volumes are elaborated, and the shape of the identified individual seismogenic fault segments is schematically represented as depth contour lines. The resulting earthquake/fault association highlights a rather complex segmentation pattern, with four neighbouring sources involved, all belonging to the SSW-dipping Ferrara Thrust System. The two main events of the Emilia 2012 sequence did not activate the Mirandola thrust underlying the Cavone reservoir, although this thrust was illuminated by some subsidiary activity mainly concentrated close to the hydrocarbon field. The likelihood of triggered seismicity effects due to the extraction/ injection activities within the Cavone oil field are discussed.
{"title":"Was the Mirandola thrust really involved in the Emilia 2012 seismic sequence (northern Italy)? Implications on the likelihood of triggered seismicity effects","authors":"G. Lavecchia, R. Nardis, G. Costa, L. Tiberi, F. Ferrarini, D. Cirillo, F. Brozzetti, P. Suhadolc","doi":"10.4430/BGTA0162","DOIUrl":"https://doi.org/10.4430/BGTA0162","url":null,"abstract":"We present the results of an interdisciplinary study aimed at defining the geometry of the fault segments activated by the Emilia 2012 thrust sequence (MW up to 6.1), which are located at the front of the Ferrara Arc (northern Italy) and partially overlap with an area undergoing hydrocarbon exploitation since 1980 (Cavone oil field). We relocate 40 well-recorded earthquakes with MW prevailingly ≥4.0 in the time interval from May 20 to June 12, 2012, plus an event that occurred in a nearby area on July 17, 2011 (MW 5.0). The geological and seismotectonic setting of the area is discussed, some interpretative geological sections across the hypocentral volumes are elaborated, and the shape of the identified individual seismogenic fault segments is schematically represented as depth contour lines. The resulting earthquake/fault association highlights a rather complex segmentation pattern, with four neighbouring sources involved, all belonging to the SSW-dipping Ferrara Thrust System. The two main events of the Emilia 2012 sequence did not activate the Mirandola thrust underlying the Cavone reservoir, although this thrust was illuminated by some subsidiary activity mainly concentrated close to the hydrocarbon field. The likelihood of triggered seismicity effects due to the extraction/ injection activities within the Cavone oil field are discussed.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70798133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The seismic hazard resulting from seismicity induced by human activity is not yet regulated in Italy. The presence of a significant natural seismicity complicates the differentiation of events possibly induced by human activity from ordinary natural seismicity, while it stimulates a comparison between the ground motion that can be expected due to tectonic events and the shaking caused by man-induced events. The problem is complicated by the fact that it is not possible to compare homogeneous hazard estimates for the two classes of seismicity, since it is difficult to define the induced seismicity in terms of probabilities for a given return time. This paper provides an example of how the problem was first tackled in an Environmental Impact Assessment (EIA) procedure, and then attempts a nationwide extension of the results.
{"title":"Seismic hazard from natural and induced seismicity: a comparison for Italy","authors":"M. Mucciarelli, E. Priolo, M. Santulin, A. Tamaro","doi":"10.4430/BGTA0158","DOIUrl":"https://doi.org/10.4430/BGTA0158","url":null,"abstract":"The seismic hazard resulting from seismicity induced by human activity is not yet regulated in Italy. The presence of a significant natural seismicity complicates the differentiation of events possibly induced by human activity from ordinary natural seismicity, while it stimulates a comparison between the ground motion that can be expected due to tectonic events and the shaking caused by man-induced events. The problem is complicated by the fact that it is not possible to compare homogeneous hazard estimates for the two classes of seismicity, since it is difficult to define the induced seismicity in terms of probabilities for a given return time. This paper provides an example of how the problem was first tackled in an Environmental Impact Assessment (EIA) procedure, and then attempts a nationwide extension of the results.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70798088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Balasco, V. Lapenna, G. Romano, A. Siniscalchi, T. A. Stabile, L. Telesca
{"title":"The Pollino 2011-2012 seismic swarm (southern Italy): First results of the ML=3.6 aftershock recorded by co-located electromagnetic and seismic stations","authors":"M. Balasco, V. Lapenna, G. Romano, A. Siniscalchi, T. A. Stabile, L. Telesca","doi":"10.4430/BGTA0138","DOIUrl":"https://doi.org/10.4430/BGTA0138","url":null,"abstract":"","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70797804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The linear Amplitude-Versus-Angle (AVA) inversion has become a standard tool in deep-sediments hydrocarbon exploration since its introduction in the oil and gas industry. However, in the last decades, with the increase of offshore construction activity, applications of this method have been also extended to predict overpressured zones and/or to evaluate the geotechnical properties of shallow sea bottom layers. Among the input parameters requested by linear AVA inversion there is the background Vp/Vs ratio across the reflecting interface and a Vp/Vs ratio of two is frequently assumed. This value is usually very close to the true ratio in case of deep, compacted sediments but it can be a gross underestimation of the true value in case of shallow or overpressured sediments. Despite that, the importance of the background Vp/Vs ratio in AVA inversion is frequently underrated and thus I consider two frequently used approximations of the Zoeppritz equations to study their impact on the outcomes of linear AVA inversion: the three-term Aki and Richards equation and the two-term Ursenbach and Stewart formula. These equations are then analysed, varying the Vp/ Vs value, using tools frequently applied in sensitivity analysis. It turns out that the background Vp/Vs ratio controls the error propagation from data to model space and determines the cross-talk between the inverted parameters. Moreover, an increasing Vp/Vs ratio causes a decrease of stability of the AVA inversion and worsens the estimate of the Vs contrast at the reflecting interface.
{"title":"The importance of the Vp/Vs ratio in determining the error propagation, the stability and the resolution of linear AVA inversion: A theoretical demonstration","authors":"M. Aleardi","doi":"10.4430/BGTA0156","DOIUrl":"https://doi.org/10.4430/BGTA0156","url":null,"abstract":"The linear Amplitude-Versus-Angle (AVA) inversion has become a standard tool in deep-sediments hydrocarbon exploration since its introduction in the oil and gas industry. However, in the last decades, with the increase of offshore construction activity, applications of this method have been also extended to predict overpressured zones and/or to evaluate the geotechnical properties of shallow sea bottom layers. Among the input parameters requested by linear AVA inversion there is the background Vp/Vs ratio across the reflecting interface and a Vp/Vs ratio of two is frequently assumed. This value is usually very close to the true ratio in case of deep, compacted sediments but it can be a gross underestimation of the true value in case of shallow or overpressured sediments. Despite that, the importance of the background Vp/Vs ratio in AVA inversion is frequently underrated and thus I consider two frequently used approximations of the Zoeppritz equations to study their impact on the outcomes of linear AVA inversion: the three-term Aki and Richards equation and the two-term Ursenbach and Stewart formula. These equations are then analysed, varying the Vp/ Vs value, using tools frequently applied in sensitivity analysis. It turns out that the background Vp/Vs ratio controls the error propagation from data to model space and determines the cross-talk between the inverted parameters. Moreover, an increasing Vp/Vs ratio causes a decrease of stability of the AVA inversion and worsens the estimate of the Vs contrast at the reflecting interface.","PeriodicalId":50728,"journal":{"name":"Bollettino Di Geofisica Teorica Ed Applicata","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70798025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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